Minnesota Classic Glastron Forum
General Category => General Discussion => Topic started by: Neutron68 on September 22, 2013, 10:40:20 AM
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Is it easy to install an electronic ignition kit in a 1978 Mercruiser 120 engine?
Just remove the points and condensor and install the electronic module?
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Correct, there are instructions in with the pertronix kits it is very simple and straight forward. I have one installed on my 120 and have not had any issues.
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I have one on my 3.7 liter, they're easy to install. Use a timing light to verify timing before and after installation because it may change a little once the Pertronix is installed. Also, it may work better to wire the positive lead of the Pertronix to a point in the ignition circuit before the ballast resistor instead of to the positive terminal of the coil otherwise you may lose power if you operate your trim while the engine is running.
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I don't have a timing light.
What happens if it just swap the parts and make the prescribed connections as instructed, without adjusting the timing?
As I understand the electronic ignition kit, it fires based on magnetic sensor that senses the rotation of the distributor shaft.
Since the same shaft is used, won't the timing stay the same?
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As I understand the electronic ignition kit, it fires based on magnetic sensor that senses the rotation of the distributor shaft.
Since the same shaft is used, won't the timing stay the same?
Not necessarily. The point at which each pulse is sensed may be in a slightly different location from where the points arm gets lifted as it rides on the lobe of the cam, so you'd have to compensate for the difference by adjusting the timing. The difference, if any, is going to be slight but it's still a good idea to set the timing once the sensor is installed. If you don't check/set the timing then either your idle speed is going to be too fast or too slow depending on which direction the off-set is, and this also effects the wide open throttle timing which will either be too advanced or not advanced enough.
Points Ignition:
(http://i425.photobucket.com/albums/pp340/Rattan3973/V174%20Floor%20Construction/Engine%20Installation/IMG_0217.jpg)
Electronic Conversion:
(http://i425.photobucket.com/albums/pp340/Rattan3973/V174%20Floor%20Construction/Engine%20Installation/IMG_0219.jpg)
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What do the red and black wires on the magnetic sensor connect to?
If some new ignition module, does that come with the retrofit kits?
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I don't have a timing light.
Buy one!
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What do the red and black wires on the magnetic sensor connect to?
The black wire connects to the negative terminal of the ignition coil, just as the points have been connected to the coil. The red wire connects to a 12v+ source of the ignition circuit, most often the positive terminal of the ignition coil but I chose to connect mine to the terminal on the heater coil of the electric choke because that is a point in the ignition circuit that is before the coil's ballast resistor.
If some new ignition module, does that come with the retrofit kits?
Huh? ???
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The question got answered.
But to clarify, I was asking if the red and black wires connected to some new ignition module (not pictured)?
And if so, did that additional module come with the retrofit kits? Or would I have to also buy that box?
You see, I've been finding that there's often some addition thing you need to buy, when you buy a new boat part.
For example, you can buy a brand new aluminum propeller for around $120, BUT you need to buy a $50 adpater kit in order to use the new prop with your 1978 drive!
See what I'm getting at?
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Yes, I understand. ;)
With the Pertronix no additional hardware or modules are needed, it comes with all that is required.
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If your points still work fine leave it alone. I had problems with Petronics.
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If your points still work fine leave it alone. I had problems with Petronics.
Like what? I've had no problems with mine.
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Me either and sold hundreds of them at work without issue.
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The reason I'm thinking of replacing the old points system is becuase the repair shop that just refurbished the lower unit and drive unit said the points were burned and the condenser was rusty. There is mounting evidence that one of the previous owners let water condence in various parts of the engine. The marine shop (just north of Cold Spring, MN) advised replacing the distributor cap, points, condenser, spark plug wires and spark plugs. I didn't have them do that work because they quoted parts and labor at $291 for all that. My thought is that if they need replacing, I don't want to replace them with the old technology that will require replacing and gapping again and again. I want to do this once and never again.
For reference, the last car my family had with pionts in it was a 1974 Suburu and we sold it in 1981. I haven't seen points since then!
Eric
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Ever since I installed one on my engine the timing has been rock solid, no wavering, and I don't have to worry about changing points and condenser anymore. To me it's much more reliable.
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Ever since I installed one on my engine the timing has been rock solid, no wavering, and I don't have to worry about changing points and condenser anymore. To me it's much more reliable.
Same here, no replacing parts, and starts better IMO.
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Ever since I installed one on my engine the timing has been rock solid, no wavering, and I don't have to worry about changing points and condenser anymore. To me it's much more reliable.
That's awesome. I look forward to similar performance.
Are all the kits the same? Should any brand be avoided?
Eric
Eric
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Pertronix is the original that all are based off of. As long as they have some sort of warranty you should be fine. EBay and amazon are the best two places to find them for a good price.
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Many of the auto parts stores around here have a tool loan or rent program, put down a small deposit you get back when you return the tool (timing light). Might be an option, you probably won't need it again after you get the Pertronix kit dialed in?
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What Pertronix part number do I need for a 1978 Mercruiser 120 (4 cyl.)?
iboats.com lists a number for Sierra and Mallory, but not Pertronix
Is it a Pertronix 1146A?
http://www.go2marine.com/product/90148F/electronic-ignition-conversion-kit-delco-4-cyl-1146a.html (http://www.go2marine.com/product/90148F/electronic-ignition-conversion-kit-delco-4-cyl-1146a.html)
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What Pertronix part number do I need for a 1978 Mercruiser 120 (4 cyl.)?
iboats.com lists a number for Sierra and Mallory, but not Pertronix
Is it a Pertronix 1146A?
http://www.go2marine.com/product/90148F/electronic-ignition-conversion-kit-delco-4-cyl-1146a.html (http://www.go2marine.com/product/90148F/electronic-ignition-conversion-kit-delco-4-cyl-1146a.html)
Just looked in pertronix's ign. book it is 1146a. what ever you do do not buy the flame thrower coil they recommend, stick with the oem coil.
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That would be the correct one, as long as it's for the Delco 4 cylinder distributor. I have seen the ones from Sierra and they are Pertronix units but with a Sierra part number, #18-5297. I bought one for one of my customers and still have yet to install it for him. (pic below)
I agree to stick with the OEM ignition coil, no need to change that.
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I'm an electronics guy by profession, and I'd like to understand how the ignition system is wired.
First, I want to establish what the correct schematic is.
I found a simplified points ignition system schematic using Google Images.
Anyone know if this is correct for a Mercruiser 120?
(http://i870.photobucket.com/albums/ab264/neutron68/Glastron/sparky_points_zps2b51ffdc.jpg)
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That drawing is not quite right because the breaker points don't connect to the positive terminal of the ignition coil, they go to the negative side. Maybe this will help, just drew it up for you:
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But, the ignition coil has 3 connections (2 bolts on the side and one in the middle).
You only have 2 in your drawing. Could you add the 3rd?
see:
http://www.marineengine.com/newparts/part_details.php?pnum=MER392-806529A+1&pass_title=392-806529A+1+%3A+COIL+KIT-IGNITION+O+-+Part+replaced+by+-898253T24&replacement=-898253T24 (http://www.marineengine.com/newparts/part_details.php?pnum=MER392-806529A+1&pass_title=392-806529A+1+%3A+COIL+KIT-IGNITION+O+-+Part+replaced+by+-898253T24&replacement=-898253T24)
http://www.marineengine.com/newparts/part_details.php?pnum=MER898253T24&ptype=&Engine=&Model= (http://www.marineengine.com/newparts/part_details.php?pnum=MER898253T24&ptype=&Engine=&Model=)
I'd also like to see the distributor and spark plug location in the circuit.
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I left the center one off because it's the high voltage lead that goes to the center terminal of the distributor cap, which then branches off to the 4 spark plugs by way of the rotating rotor underneath. In terms of wiring the circuit I didn't feel it was necessary because that to me is a given. I've included it to the coil here:
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Here's a modded version showing the wiring of the Pertronix in place of the points and condenser.
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Looking at your engine pic you posted recently I see you don't have an electric choke but you can still wire the positive red wire from the Pertronix to the front side of your ballast resistor, not the back side that goes to the coil.
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I left the center one off because it's the high voltage lead that goes to the center terminal of the distributor cap, which then branches off to the 4 spark plugs by way of the rotating rotor underneath. In terms of wiring the circuit I didn't feel it was necessary because that to me is a given. I've included it to the coil here:
Thanks for adding the 3rd connection to the coil!
I have an electronics background, not an engine or automotive background.
My goal is to see of FULL schematic of the ignition system so I can understand it from an electronics standpoint.
I found some schematics for the insides of an ignition "coil", which is really a transformer, in electronics terminology.
Transformers have to at least 2 coils (windings) inside.
(http://www.kronjaeger.com/hv/hv/src/ign/ignition1.png)
(http://mgaguru.com/mgtech/ignition/pics/circ_ic.gif)
There's a really good description of how the points system works, complete with an animated graphic of the distributor.
http://auto.howstuffworks.com/ignition-system4.htm (http://auto.howstuffworks.com/ignition-system4.htm)
It also includes a very important piece of information - spark is not generated until the points (which are normally closed) are opened.
From the schematics, I can now see that when the points open, the capacitor (condenser) is allowed to charge from 0V to 12V, pulling a pulse of current through the primary coil of the transformer, which then induces a high Voltage in the secondary coil of the transformer, which is then passed on to the spark plugs.
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I too have a background in electronics so I've got an understanding in how this works. As one of my hobbies I repair antique tube radios and have a collection from the 1930's and 40's.
Here's a simple breakdown of how it operates:
Illustration 1) points closed completing the circuit through the ignition coil's primary winding. A magnetic field begins to build within the coil.
Illustration 2) points open breaking the connection and stopping the flow of current through the coil. The magnetic field collapses inducing a high voltage spike through the coil's secondary winding which is sent to the associated spark plug. Collapse backlash is absorbed by the condenser and also prolongs contact point life.
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Any idea what circuit is inside the Petronix "sensor"?
An SCR, TRIAC or FET that is triggered by the Hall-effect sensor inside?
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That I don't know, maybe it's a trade secret. ;)
However, if you were to purchase the Pertronix Ignitor II for 3 times the price of the basic Ignitor I've heard it automatically adjusts dwell time and coil voltage depending on the operating conditions for optimum efficiency.
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I too have a background in electronics so I've got an understanding in how this works. As one of my hobbies I repair antique tube radios and have a collection from the 1930's and 40's.
hijack alert...
i would like to see a few pix of that :D
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Umm ..... ok, just a teaser.
They are as follows:
1934 Emerson Console and 1942 Philco table top rado
1940 Zenith Console
1938 Zenith Shutter Dial (Robot Dial) Console
And yes, they are all functional.
I even have a 1947 Fada (RCA) Television that works, it's got a 10 inch round picture tube, B&W of course.
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so is that a "tuning eye" tube on top of the Emerson ? you have it wired in as an add on ?
they all look vary nice, did you have to work on the cabinets also ?
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Yes, that is a "magic" tuning eye on the Emerson. I added it to the set but didn't want to install it into the cabinet so I built a separate box for it. I wired it with a connector so it can be removed at any time without disturbing any of the circuits. All the cabinets are original finish, I haven't had to do anything to them except a little furniture polish. The grill cloth on the 1938 Zenith is a reproduction, all the others are original.
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I have a 1938 Zenith 12-tube floor model almost identical to the last one you have pictured.
I first saw one at the Pavak Museum in St. Louis Park and decided I wanted to own one!
I bought mine already refurbished at Great Northern Antique on Bloomington Ave in South Minneapolis.
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My friends Tim and Tom Moen sell a bunch of them on E-Bay.
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OMG!! My Grandpa and Granny had one of those in their living room. I remember him sitting and listening to the "rasslin" (wrestling) and the news while he smoked his pipe. We had to sit and be quiet during that or Granny would take one of those little switches off the walnut tree and whelp us with it. I always thought I could out run her, but I couldn't!
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I have a 1938 Zenith 12-tube floor model almost identical to the last one you have pictured.
I first saw one at the Pavak Museum in St. Louis Park and decided I wanted to own one!
I bought mine already refurbished at Great Northern Antique on Bloomington Ave in South Minneapolis.
Hmmm.... So if you have a 1938 12 tube model that's similar to my 9 tube model 9-S-262 then it's either going to be a 12-S-265 or a 12-S-267, pictured below respectively. Neither are mine but I wish they were part of my collection. I really liked those models. They are quite collectible and can be pricey if already refurbished/restored. I bet you paid over 1k for it.
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VERY cool radios!
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I have a 1938 Zenith 12-tube floor model almost identical to the last one you have pictured.
I first saw one at the Pavak Museum in St. Louis Park and decided I wanted to own one!
I bought mine already refurbished at Great Northern Antique on Bloomington Ave in South Minneapolis.
Hmmm.... So if you have a 1938 12 tube model that's similar to my 9 tube model 9-S-262 then it's either going to be a 12-S-265 or a 12-S-267, pictured below respectively. Neither are mine but I wish they were part of my collection. I really liked those models. They are quite collectible and can be pricey if already refurbished/restored. I bet you paid over 1k for it.
I just looked up the bill of sale: 12-S-265, $775 in 1995
It looks just like the first one you pictured.
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Realy Nice old radio's Rich
it suprize's me that such a young fellow in the boat world has such an interest, that's just too cool.
I grew up in a town in south east Ok. about 2500 population then, just a bit more now, we lived 5 1/5 miles south west of Antlers, Ok. My grandpa traded a battery powered electric fence charger my dad gave him for an old battery powered raidio, that was in 1959 it was not quite as big and pretty as the one's you have, but the battery was about 2ft tall by about 6 or 8" kinda square looking, and an extra battery was stored inside the radio, got no idea what kind it was, but it just had one dial in the middle kinda near the top. It was His radio, and no one else could turn it on, he was always worried about how long the battery would last, but every night, just after dark, he had grandma mix him up a hot toddy, half a glass of corn, and the rest hot water, with a spoon full of sugar, and he listened to Herbert Armstrong.
However ... om Saturday night, he did tune in into clear channel 650 Nashville Tenn. and we got to listen to the grand ole opry, good memories.
We got electricity pulled in a little after that, had a light in both rooms, and dad bought a tv, quite a deal, several people around the area would come to watch it, and Saturday nights was the "wraslin" and one family drove a wagon and team of horses over every sat night with a coal oil lantern on a pole stuck up the front side of the wagon, Gene loved to watch wraslin, he was a scraper, he and grandma would carry on like they was in the ring, grandpa would laugh out loud at her and Gene carrying on and telling them it was fake for tv, but we didn't care, it was all fun.
Thanks Rich for the memories.
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Thanks Red. I've got one "farm" radio in my collection that would interest you. Sitting on my cluttered work bench is a 1935 Philco "Tombstone" that runs on a 6 volt car or tractor battery, which would have been the norm for extreme rural areas. I haven't used it in a while but it does work. It's interesting how they work by using a vibrating tuning fork to attenuate the incoming DC voltage and step it up with a transformer to about 130 volts to power the plates in the tubes. When it's on you can hear the vibrator humming away inside the set. I don't use this radio much, for one my 6 volt car battery had died some years ago and two, some of the tubes for this set are expensive because of the time period and rarity.
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Ordered a kit for $75 off Ebay:
http://www.ebay.com/itm/1146A-Ignitor-Solid-State-Ignition-for-Mercruiser-110-120-140-165-170-180-190-/380376817756 (http://www.ebay.com/itm/1146A-Ignitor-Solid-State-Ignition-for-Mercruiser-110-120-140-165-170-180-190-/380376817756)
Other questions that came to mind:
1. what "knob" do you turn to adjust the timing?
2. is there a source for inexpensive (or free) Mercruiser service manuals (paper or PDF scan on CD), that cover the 1978 Mercruiser 120?
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To adjust the timing you loosen the retaining clamp bolt that holds the distributor into the engine block and rotate the distributor one way or the other to dial in the timing. Once the timing is set retighten the retaining bolt. A timing light is needed to set the timing.
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I just found the page on timing adjustment in the online version of the Mercruiser service manual:
http://boatinfo.no/lib/mercruiser/manuals/mercruiser3.html#/236 (http://boatinfo.no/lib/mercruiser/manuals/mercruiser3.html#/236)
Other online manuals found here:
http://boatinfo.no/lib/library.html (http://boatinfo.no/lib/library.html)
Thank you, thedeuceman! :D
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I don't see an ignition coil ballast resistor shown on the wiring diagram for Mercruiser 120 engines in my serial number range, so I suspect there isn't an external resistor.
see http://boatinfo.no/lib/mercruiser/manuals/mercruiser1.html#/308 (http://boatinfo.no/lib/mercruiser/manuals/mercruiser1.html#/308)
IF there is a ignition coil ballast resistor, what is it's likely location on the engine?
I've ordered all the pieces and parts needed to make the swap: Pertronix kit, new distributor cap, new rotor, new spark plug wire kit, new spark plugs, spark plug socket wrench, borrowed timing light.
Do I need anything else? Any other special tools?
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The wire that goes to the coil is a resistance wire, acts the same as a resistor.
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Correct, instead of a ballast resistor you have a resistance wire. When connecting ther Pertronix you need to connect the red wire at a point in the circuit before the resistance wire.
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The wire that goes to the coil is a resistance wire, acts the same as a resistor.
It that is the case, then I'd need to find the beginning of that wire, so I could connect the +12V wire of the electronic ignition module to +12V before the resistance wire.
Any idea how long it is, and if it's visually identifiable as a resistance wire?
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Correct, instead of a ballast resistor you have a resistance wire. When connecting ther Pertronix you need to connect the red wire at a point in the circuit before the resistance wire.
Actually mine is hooked right at the positive side of the coil, I have not had any issues with it.
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Connecting right to the bolts on the ignition coil would certainly be easier.
I was just going on what Rich has said in this thread.
Rich_V174SS: Also, it may work better to wire the positive lead of the Pertronix to a point in the ignition circuit before the ballast resistor instead of to the positive terminal of the coil otherwise you may lose power if you operate your trim while the engine is running.
Rich_V174SS: Looking at your engine pic you posted recently I see you don't have an electric choke but you can still wire the positive red wire from the Pertronix to the front side of your ballast resistor, not the back side that goes to the coil.
Rich_V174SS: When connecting ther Pertronix you need to connect the red wire at a point in the circuit before the resistance wire.
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Correct me if I am wrong Rich, but doesn't the resistance wire just cut the volts back to 12 from the 13.5 that the alternator puts out?
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The is correct, and running the Pertronix connected to the coil would not be a problem, the engine will still run fine. But when you start using accessories or the trim the voltage required for the Pertronix may drop below the threshold needed to keep it running. I had this problem with mine so I chose to connect it before the resistance wire and haven't had any more problems.
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I found a Mercruiser 120 side view on photobucket (its not mine and I've no idea what the black arrow is indicating).
Can someone point out:
1. the resistance wire and
2. a good place to connect the Pertronix +12 wire
(http://i683.photobucket.com/albums/vv200/cj8mule/1978%20SS%2018/switch.jpg)
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That's not a great pic to make out specific wires. There should currently be two wires on the positive terminal of the ignition coil, one purple and the other purple/yellow. The plain purple one is the resistance wire, the one with the yellow stripe is a bypass that goes to a terminal on the starter solenoid. The resistance wire ties into the purple wire that goes to the alternator and (if you had one) the electric choke, the connection may be hidden within the harness wrap. This line becomes live when the keyswitch is turned on. The purple/yellow wire (bypass) is only active when cranking the engine to provide a boost to the coil by bypassing the resistance wire.
The black circle with arrow is indicating either a switch or terminal block for wires that are not relevant to our situation.
Here's a Mercruiser 120 wiring diagram I found, not the most clear but it's all I have. The dotted line indicates the resistance wire.
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I believe this is the correct wiring diagram for my engine.
It has a 40A circuit breaker rather than a fuse:
http://boatinfo.no/lib/mercruiser/manuals/mercruiser1.html#/308 (http://boatinfo.no/lib/mercruiser/manuals/mercruiser1.html#/308)
In terms of a pre-resistor place to connect to 12V, how about:
1. at the 40A circuit breaker or
2. a 12V connection point at the starter solenoid?
(http://i870.photobucket.com/albums/ab264/neutron68/Glastron/generic-120-engine-12V-notes_zpsae110428.jpg)
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Those would be live all the time so if you connected to either of those locations you wouldn't be able to shut off the engine. The purple wire going to the alternator would be the most viable location you can tap into, or strip back some of the wrap near the main harness plug and tap into the purple wire there. That line is controlled by the keyswitch, on and off.
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Actually, lemme rephrase that:
If you connected the Pertonix to those locations you mentioned then the sensor module would be live all the time, even without the engine running. The coil would still be controlled by the keyswitch but there would be nothing to turn off the Pertronix module.
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I believe this is the correct wiring diagram for my engine.
http://boatinfo.no/lib/mercruiser/manuals/mercruiser1.html#/308 (http://boatinfo.no/lib/mercruiser/manuals/mercruiser1.html#/308)
Can you tell which wire color is a key-switched 12V on this diagram?
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That on-line manual doesn't work right for me, it won't go to the page you indicated unless I go page-by-page manually from the beginning. I don't have to see the manual to know what color wire, I already know it's the purple wire like I've been saying all along. That was also indicated in the wiring diagram I posted.
Here's what I suggest: Try it by connecting the red and black wires directly to the ignition coil, to the positive and negative terminals respectively. If you have any trouble running the engine when power is being used elsewhere then relocate the red wire pre-resistance. Otherwise leave it as-is, plain and simple. What have you got to lose?
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That on-line manual doesn't work right for me, it won't go to the page you indicated unless I go page-by-page manually from the beginning.
Try copying the web address and pasting it into the address line of your web browser.
http://boatinfo.no/lib/mercruiser/manuals/mercruiser1.html#/308 (http://boatinfo.no/lib/mercruiser/manuals/mercruiser1.html#/308)
That worked for me in Chrome and Internet Explorer. But, Internet Explorer literally took 30-60 seconds to show me the page.
I don't have to see the manual to know what color wire, I already know it's the purple wire like I've been saying all along.
In the diagram I'm referencing, the purple wire goes to the oil pressure sender. The wire to the alternator is red/white.
Here's what I suggest: Try it by connecting the red and black wires directly to the ignition coil, to the positive and negative terminals respectively. If you have any trouble running the engine when power is being used elsewhere then relocate the red wire pre-resistance. Otherwise leave it as-is, plain and simple. What have you got to lose?
I could do that, but I'd prefer to wire it up as you suggested earlier, to ensure no problems.
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In the diagram I'm referencing, the purple wire goes to the oil pressure switch. The wire to the alternator is red/white.
Take a look on your engine to see if the wire colors match your diagram. You could be looking at a diagram for an older engine pre-1973.
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I can't look at the engine until this weekend. It's 80 miles away from me right now. :)
The page I'm referencing says it's for Mercruiser 120 serial numbers 3770650 and up.
My serial number is 4952735, which is greater than 3770650, so it's in the right range.
I converted page 308 to a picture file for you.
(http://i870.photobucket.com/albums/ab264/neutron68/Glastron/120-wiring-diagram_zps6e287531.png)
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Ok, if this diagram accurately matches your engine then white is ignition powered by the key instead of purple. The white wire from the harness connector becomes your resistance wire to the coil. The bypass wire from the starter solenoid I think is tan if I read that right.
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Rich, did you get your web browser problem figured out yet? If not, please keep trying. What browser are you using?
That online manual is handy, AND I'd like to be able to refer to a page and have you be able to open up a web browser and look at it, too.
I'll check on the wire colors this weekend.
I thought of needed tool for the ignition upgrade that no one has suggested - a spark plug gapper!
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Yeah I got it to work, thanks. The manual doesn't open up to the page indicated in the address line but I was able to input the page at the bottom of the screen and go to it that way.
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I'm glad you got the online manual working Rich! Now, you can reference a page number and I can go look at that exact same page!
The wire colors matched the page I reference from the online manual.
The alternator wire was red-white. The + side of the coil was Tan. The - side of the coil was black.
I changed the plugs, plug wires, distributor cap, and installed the Pertronix module. The old plugs were pretty sooty.
The previous owner said the engine was "redone" last year, but the state of the plugs makes me wonder how much they "redid"?
The old sooty plugs were R44T and the 1978 Mercruiser owners manual says it should have R43T plugs.
The marine shop recommended BR6FS, so that's what I just installed.
After it stops raining, I plan to wheel the boat outside and hook up the water earmuffs and start the engine.
When we had the boat out this summer, I noted that the idle when in gear was around 1000 RPM. The 1978 Mercruiser owners manual says the idle RPM should be 650-700 RPM, so I think I should adjust the idle speed before adjusting the timing.
(http://i870.photobucket.com/albums/ab264/neutron68/Glastron/20131005_205040_resized_zps45e1d82e.jpg)
(http://i870.photobucket.com/albums/ab264/neutron68/Glastron/20131005_223144_resized_zpsae4f3cbb.jpg)
(http://i870.photobucket.com/albums/ab264/neutron68/Glastron/20131005_231836_resized_zpse619f755.jpg)
(http://i870.photobucket.com/albums/ab264/neutron68/Glastron/20131005_232451_resized_zps579f30c3.jpg)
(http://i870.photobucket.com/albums/ab264/neutron68/Glastron/20131005_232004_resized_zps4f1843f5.jpg)
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I'm glad you got the online manual working Rich! Now, you can reference a page number and I can go look at that exact same page!
The wire colors matched the page I reference from the online manual.
The alternator wire was red-white. The + side of the coil was Tan. The - side of the coil was black.
I changed the plugs, plug wires, distributor cap, and installed the Pertronix module. The old plugs were pretty sooty.
The previous owner said the engine was "redone" last year, but the state of the plugs makes me wonder how much they "redid"?
The old sooty plugs were R44T and the 1978 Mercruiser owners manual says it should have R43T plugs.
The marine shop recommended BR6FS, so that's what I just installed.
After it stops raining, I plan to wheel the boat outside and hook up the water earmuffs and start the engine.
When we had the boat out this summer, I noted that the idle when in gear was around 1000 RPM. The 1978 Mercruiser owners manual says the idle RPM should be 650-700 RPM, so I think I should adjust the idle speed before adjusting the timing.
Sooty plugs means it's running "rich". Either the idle mix is open a little too much or the carburetor is dumping fuel down the venturies. AC MR43T plugs are equivalent to NGK BR6FS so either are fine.
When adjusting idle speed and timing first get the idle within ballpark and then dial in the timing. If the idle drops too low when setting the timing then raise the idle speed up to compensate. Once timing is set adjust your idle mix screws on the base of the carburetor for fastest idle, again compensating with the idle stop/set screw to keep the idle around 750-800. Then turn the idle mix screws open an eighth turn from their setting to slightly enrich the carburetor, this helps for when the boat is in the water to counter exhaust pack pressure.
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I believe the idle speed adjustment screw is on the back side of the carburetor? It sets the limit of a spring-loaded throttle lever, correct?
I think they are showing it in on page 42 (top right photo).
http://boatinfo.no/lib/mercruiser/manuals/mercruiser1.html#/42 (http://boatinfo.no/lib/mercruiser/manuals/mercruiser1.html#/42)
And again on page 44 (top left)
http://boatinfo.no/lib/mercruiser/manuals/mercruiser1.html#/44 (http://boatinfo.no/lib/mercruiser/manuals/mercruiser1.html#/44)
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Yep
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Of note, I was not able to replace the rotor. The replacement rotor I bought was slightly different from the original (even though it was the correct part number), so it did not lock in place on the distributor shaft, when the Pertronix magnet ring was in place under it. So, I had to reuse the original rotor.
The rain finally stopped around 3pm Sunday afternoon, so I wheeled the boat out onto the driveway, put the water muffs on and started the engine. It started and ran! The idle speed was around 800 RPM. (one tick below 1000 RPM) I may have misremembered 1000 RPM at idle?
I decreased the idle speed a little, but then the engine was running a little more rough (this with new plugs, new plug wires, new distributor and Pertronix module). I turned it back up to 800 RPM. I did not adjust any carburetor jets.
With the timing light I, saw that the timing was 6-7 degrees BTDC at 800 RPM idle. The 1978 Mercruiser manual says it should be 8 degrees.
I noted that the timing light did not fire with every engine revolution (missing flashes).
I'm not sure if this was a malfunctioning timing light (which I borrowed) or if there was really a missing spark every so often?
The bolt to loosen the distributor module was in a tight spot and I could not get a wrench on it!! So I could not adjust the timing.
How can I loosen that bolt??
(http://i870.photobucket.com/albums/ab264/neutron68/Glastron/20131005_232451_resized_zps579f30c3.jpg)
I took a movie of the engine running at the 800 RPM idle.
In it, I am questioning whether the engine is running normally?
For reference, the outside temperature is 49 F.
https://docs.google.com/file/d/0B1dmlpYq0PhJbUFhdmE5S05fXzQ/edit?usp=sharing (https://docs.google.com/file/d/0B1dmlpYq0PhJbUFhdmE5S05fXzQ/edit?usp=sharing)
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You can get a wrench on it. You can only turn it about 1/2 flat per turn though. It's a tight fit but doable. Your timing is off a little and might be causing the rough idle too.
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With the timing light I, saw that the timing was 6-7 degrees BTDC at 800 RPM idle. The 1978 Mercruiser manual says it should be 8 degrees.
6 degrees is pretty close. What does it say on the info sticker on the side of the valve cover? They have spark plug and timing info listed on the sticker right above your ignition coil.
I'm not sure if this was a malfunctioning timing light (which I borrowed) or if there was really a missing spark every so often?
Spark occurs every other revolution of the crank when the piston is at the top of the compression stroke. If the light seems to be missing it could be because of how the inductance clip is positioned on the #1 plug wire, position can affect its sensitivity.
The bolt to loosen the distributor module was in a tight spot and I could not get a wrench on it!! So I could not adjust the timing. How can I loosen that bolt??
The best tool to use on that bolt is a 12-point box wrench, I think it's half-inch. Just loosen it enough to get the distributor to move but be careful, your adjustment is going to be ever so slight. Sometimes when you lock it back down the distributor will shift a little and can throw off the setting. It takes a little trial an error but you'll get it. I also like to apply a drop of White-Out with a toothpick onto the timing mark of the crank pulley to make it easier to see against the timing scale. You can also use it to highlight the mark on the scale that you're shootin' for.
After watching your video it seems your valves lifters or pushrods are tapping away something fierce, they shouldn't be making that much noise. Maybe they need to have the valve lash adjusted a bit.
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The sticker also says 8 degrees BTDC.
(http://i870.photobucket.com/albums/ab264/neutron68/Glastron/6a959774-165a-41d4-9f93-59227c9179ab_zps63846366.jpg)
(http://i870.photobucket.com/albums/ab264/neutron68/Glastron/20131005_110143_resized_zps24f7846a.jpg)
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There are 2 sources that confirm the setting so then it should be set at 8 degrees BTDC.
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There are 2 sources that confirm the setting so then it should be set at 8 degrees BTDC.
Agreed.
So, what kind of engine operation would you expect to see/hear if the timing was off by 1-2 degrees?
Rough idle at 650-700 RPM?
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A change in timing going from 6 to 8 degrees will increase idle speed slightly. Then you compensate for it with the idle stop screw on the carburetor to get it to your target rpm. A setting of 6 degrees will have a lower overall high speed setting than if it were at 8 degrees, the engine will run better at high speed if the full speed timing is also where it should be. The cause for a rough idle could be caused from a number of things like improperly adjusted idle mix screws on the carburetor, a carb that is flooding or in need of a rebuild, improperly set up valve lash or leaking valves causing cylinder imbalance. I try to shoot for an 800 rpm setting on land because it may drop slightly when the boat is in water due to exhaust back-pressure.
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When I had the boat in the shop (with the points ignition system) they measured the cylinder compression:
CYL 1 - 162 PSI
CYL 2 - 160 PSI
CYL 3 - 160 PSI
CYL 4 - 154 PSI
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Those compressions are damn good, better than my old 120 which was about 145 per cylinder. Typical compression reading are usually 140-145 psi. That cylinder #4 reading of 154 is still within tolerance of the others, 10%.
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Of note, I was not able to replace the rotor. The replacement rotor I bought was slightly different from the original (even though it was the correct part number), so it did not lock in place on the distributor shaft, when the Pertronix magnet ring was in place under it. So, I had to reuse the original rotor.
Ever heard of the rotor not fitting when the Pertronix magnet ring is on the rotor shaft?
After it lined up the magnet ring with the square shaft, I pushed the rotor down as far as it would go, so I know that isn't the problem. I could actually see that the plastic tongue at the top of the inside of the rotor is not as long as the tongue in the original rotor. I'm thinking I should ask someone from Pertronix if this is a known problem.
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Shoot me a picture of the new rotor and I'll tell you if it's the right one.
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Shoot me a picture of the new rotor and I'll tell you if it's the right one.
I can't shoot a picture. I left the rotor with the boat, 80 miles away.
The outsides of the rotors look exactly the same. You'd conclude it was right part if you saw them side-by-side.
The difference is INSIDE the rotor.
The plastic tongue at the top of the inside of the rotor is not as long as the tongue in the original rotor, thus it does not lock into the slot of the rotor shaft, when the Pertronix magnet ring is on the rotor shaft
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SURE it's not just pushed down all the way?
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It could be a Chinese knock-off, Mercury has been using them lately. I went to buy a tune-up kit for the same Delco style 4 cylinder distributor from my local Mercury parts dealer about a month ago. The kit consisted of a set of points and condenser. The condenser was made in Mexico I think and the points were made in China. The points were inferior to the US made ones I was replacing. So I only used the condenser and left the old points in place. My customer's engine has been running good since because all it needed was the condenser to solve his problem. He's getting a Pertronix installed anyway so this was just to hold him over until I got it.
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SURE it's not just pushed down all the way?
Yes, VERY sure.
I switched back and forth between the new and old to be sure. The old rotor's tongue engaged with the slot in the distributor shaft and the new would not engage. And, when I looked down the holes in the rotors I could see that the new tongue was smaller than the old.
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It could be a Chinese knock-off, Mercury has been using them lately. I went to buy a tune-up kit for the same Delco style 4 cylinder distributor from my local Mercury parts dealer about a month ago. The kit consisted of a set of points and condenser. The condenser was made in Mexico I think and the points were made in China. The points were inferior to the US made ones I was replacing. So I only used the condenser and left the old points in place. My customer's engine has been running good since because all it needed was the condenser to solve his problem. He's getting a Pertronix installed anyway so this was just to hold him over until I got it.
I bought it from West Marine in Minnetonka. I think it was either a Quicksilver or Sierra branded part. I'll dig out my receipt tonight and see if the part number is on there.
Later...
It turns out I did bring the part back to the city! Here are some photos.
(http://i870.photobucket.com/albums/ab264/neutron68/Glastron/774d0073-e02a-45dc-9374-d07869bedf0f_zps45e072e9.jpg)
(http://i870.photobucket.com/albums/ab264/neutron68/Glastron/ddbdac98-810b-4b08-8857-82ada57bec8a_zps2616eced.jpg)
(http://i870.photobucket.com/albums/ab264/neutron68/Glastron/bb4e9a61-4d3d-4fea-95ed-2b90adc96685_zpsa871c88f.jpg)
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It does look a little different than my Delco rotor. I guess when they source out different manufacturers they're not all going to be the same.
(http://i425.photobucket.com/albums/pp340/Rattan3973/V174%20Floor%20Construction/Engine%20Installation/IMG_0219.jpg)
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It does look a little different than my Delco rotor. I guess when they source out different manufacturers they're not all going to be the same.
You said you were doing an electronic ignition conversion for a customer?
What rotor part number did you order? I should get one of those!
This 58217Q is clearly NOT a good fit!
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I don't remember what the number was but I think it was part of a combo package where you get cap and rotor together. The rotor hardly ever wears so if the older one is working for you just keep using it until you can find another like it. Sometime you get a little corrosion on the electrode tip but a little wire brushing or some fine emery cloth or sand paper can clean it up smooth and shiny.
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Any thoughts on the look and amount of exhaust in the movie?
My lake neighbor thought it was steam content due to the exhaust mixing with water in the exhaust manifold, and the fact that the outside temperature was 49 degrees F.
https://docs.google.com/file/d/0B1dmlpYq0PhJbUFhdmE5S05fXzQ/edit?usp=sharing
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The steam could be because the outside temperature is cold. But it could also be from not having enough water flowing through the exhaust elbow on top of the exhaust manifold. If there's not enough flow it could be the elbow is plugged up with rust. I had that problem once and replaced the elbow.
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The steam could be because the outside temperature is cold.
OK, it sounds like you agree with my lake neighbor's thoughts....water + exhaust + 49F air temperature = steam in the exhaust
But it could also be from not having enough water flowing through the exhaust elbow on top of the exhaust manifold. If there's not enough flow it could be the elbow is plugged up with rust. I had that problem once and replaced the elbow.
During the winterize, the RV antifreeze went into the elbow on the top of the exhaust manifold without any obstructions. And there was water that drained out of the exhaust manifold plug, so there was clearly water in there.
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Yes, but how much water was coming out with the exhaust behind the boat? It should be pouring out of at least one of the ports on the side of the transom shield. See my video below:
https://www.youtube.com/watch?v=TXX7wYnBsxs (https://www.youtube.com/watch?v=TXX7wYnBsxs)
If the elbow is plugged up your engine temperature will slowly rise and may eventually overheat when you're driving the boat.
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Yes, but how much water was coming out with the exhaust behind the boat? It should be pouring out of at least one of the ports on the side of the transom shield. See my video below:
https://www.youtube.com/watch?v=TXX7wYnBsxs (https://www.youtube.com/watch?v=TXX7wYnBsxs)
If the elbow is plugged up your engine temperature will slowly rise and may eventually overheat when you're driving the boat.
I see water coming out of the drive unit in several places: upper drive unit and lower drive unit.
You can see the lower unit water exiting in the video I made.
I don't know what normal is supposed to look/sound like, which is exactly why I made the video for you.
(http://i870.photobucket.com/albums/ab264/neutron68/Glastron/Mercruiser-120_water-outlets_zpsca95d280.jpg)
The water coming out of the upper part of the drive unit is propelled by exhaust, like it's spitting, not gushing.
(http://i870.photobucket.com/albums/ab264/neutron68/Glastron/outboard-section_water-outlet_zps989153c0.jpg)
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It should be pouring out as much water as your hose is feeding it and hopefully you've got the water on full. If it's spitting and it's hot to the touch then the outlet holes in the elbow could be plugged up. If there's not enough water coming out the elbow is restricting it, and what little that does come out becomes steam when it hits the hot exhaust.
Compare your video to my video.
Also, when you run your engine you should have the drive down so it's perpendicular to the ground as much as possible. Don't run it way up in the air, it stresses the U-joints.
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I believe the water was on at least 75% to full, but probably not 100% full. No I wouldn't say water gushes out of the upper drive unit. It spits out the top and runs out the bottom as you can see.
I didn't feel the water coming out the drive unit. The water in the exhaust manifold was hot when I drained it. It made me pull my hand away quickly when I unscrewed the plug.
Is the elbow you are talking about in the back side of the engine? If so how would I check it for rust plugs or clean out rust plugs?
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The exhaust elbow is mounted on top of the exhaust manifold in the back. Four nuts/bolts and a couple large hose clamps remove it. When reinstalling you would need a new gasket. There are water passages from the manifold to the elbow and on the exit side there are 3 or 4 holes inside the spout where the water exits and mixes with the exhaust, on the down-tube side. These holes clog up over time, and usually warrant replacing the elbow. Below is a picture of the elbow on top of my old 120 engine. The second pic shows the outlet side of the elbow from my newer 3.7 liter engine where the outlet holes are all closed up. Your water outlet holes will be inside the tube, not along the outer edge as shown in my pic. I replaced the elbow on both my engines because of "clogged artery disease".
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Thanks for the pictures - helpful!
Here's the parts list and diagram for that section of the Mercruiser 120:
http://www.marineengine.com/parts/mercruiser-sterndrive-parts/120-gm-153-il4-19721978/3377341-thru-5192048/exhaust-manifold-assembly-end-cap-and-elbow-assembly (http://www.marineengine.com/parts/mercruiser-sterndrive-parts/120-gm-153-il4-19721978/3377341-thru-5192048/exhaust-manifold-assembly-end-cap-and-elbow-assembly)
It looks like an exhaust elbow is around $140. It would be good to know if its plugged before ordering a new one.
Can I get to those bolts and hose clamps with the engine mounted in place?
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With a decent set of box wrenches you should be able to get the elbow off. You don't need to pull the engine out. A screw driver is needed to loosen the hose clamps that connect the elbow to the rubber boot behind the engine. I try to get only Mercury parts when available. Sometimes the aftermarket parts are inferior. If you are going to pull the elbow off you should drain the manifold and elbow first so water or antifreeze doesn't flow into the exhaust chamber of the manifold and flood into the engine cylinders when you break the gasket seal.
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With a decent set of box wrenches you should be able to get the elbow off. You don't need to pull the engine out. A screw driver is needed to loosen the hose clamps that connect the elbow to the rubber boot behind the engine. I try to get only Mercury parts when available. Sometimes the aftermarket parts are inferior. If you are going to pull the elbow off you should drain the manifold and elbow first so water or antifreeze doesn't flow into the exhaust chamber of the manifold and flood into the engine cylinders when you break the gasket seal.
Understood, on draining the antifreeze from the exhaust manifold, before elbow removal.
What do you think of putting a petcock in the exhaust manifold drain hole, for ease of use? Will it clog up?
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They drain better and are easier to unclog when it's just a brass plug screwed in there.
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If the elbow is not too bad, I've seen Muriatic acid work wonders on cleaning out the gunk.
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I found my replacement 120 elbow in storage. I bought it used from ebay cheap a number of years ago and intended to replace the one on my 120 engine but never got around to it because I ended up replacing the whole engine with the 3.7 liter I now have in my boat. In the pic you can see the 3 water outlet holes as they should be - clean, defined, and unobstructed.
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I found my replacement 120 elbow in storage. I bought it used from ebay cheap a number of years ago and intended to replace the one on my 120 engine but never got around to it because I ended up replacing the whole engine with the 3.7 liter I now have in my boat. In the pic you can see the 3 water outlet holes as they should be - clean, defined, and unobstructed.
Thanks for the photo. I was wondering how a Mercruiser 120 elbow should look on the inside.
On the amount of water coming out of the boat rear end, there was more coming out of the lower end than the upper part of the drive unit. I didn't have the cabin's faucet at 100%, but then again, even at 100%, the cabin's water never gushes like city water pressure does! So, the input volume may not be up to city water pressure standards!
I guess I'm not going to be sure about the water output until I take the elbow apart and look in the output section, or run the engine again in the spring and evaluate the amount of water coming out the upper part of the outboard unit.
Eric
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I looked at the distributor assembly bolt again this weekend.
I could NOT get either end of the wrench on the bolt head. I tried several sizes and it seemed like 9/16 was the closest.
The open end 9/16 was too thick to go between the bolt and the pole the distributor is on. The 9/16 boxed end ALMOST fit over the bolt head, but it was also too thick to go between the bolt and the pole the distributor is on. My boxed end wrench is one of the ratcheting kind.
I'm guessing some special wrench is needed for this?
Can someone quote a model number and maker of a known-compatible wrench?
(http://i870.photobucket.com/albums/ab264/neutron68/Glastron/20131020_192508_zpse55066b5-1-1-1.jpg)
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I went to try removing the bolts of the exhaust elbow to check it for rust plugs of the water passages.
I could NOT get a wrench on the 2 recessed bolts! I tried a socket for a socket wrench and I could not even get the socket (without wrench handle) to go into that recess!!
What kind of special wrench does this bolt need?
Model number and maker, if you know of a compatible wrench.
(http://i870.photobucket.com/albums/ab264/neutron68/Glastron/20131020_192352_zpsbf4d41aa-1.jpg)
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No special tools are required. Simple 'quality' 12-point box-end or slender open-end wrenches are all that is needed. No Chinese cheapies with poor metallurgy or fancy ratcheting gear wrenches. See pic below.
On another note: I installed a Pertronix for one of my customers today and ran into the same problem you had with the rotor not fitting with the magnetic wheel installed. I had to dig into my box-o-stuff and find a "shorty" rotor that worked in it's place.
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Offset Distributor wrench, offset box wrench, crow's foot, waterpump wrench. flex-socket works too.
(http://i256.photobucket.com/albums/hh181/50sflash/not%20my%20boat/IMG_0600_zpseb32f6eb.jpg)
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Did you try going between the block and fuel pump? It does kind of sound like you have "heavy" wrenches. Seems like a lot of time the cheaper wrenches are sloppier and don't you grab the hex as well too. I use craftsman and have done my timing plenty of times with them.
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Did you try going between the block and fuel pump? It does kind of sound like you have "heavy" wrenches. Seems like a lot of time the cheaper wrenches are sloppier and don't you grab the hex as well too. I use craftsman and have done my timing plenty of times with them.
No, I didn't.
How about this wrench set? Does the bolt end look thin enough?
http://www.ebay.com/itm/5-PC-S-SHAPED-BOX-END-TYPE-WRENCH-TOOL-SET-SAE-STANDARD-SIZED-ANGLE-ANGLED-BENT-/290878823661 (http://www.ebay.com/itm/5-PC-S-SHAPED-BOX-END-TYPE-WRENCH-TOOL-SET-SAE-STANDARD-SIZED-ANGLE-ANGLED-BENT-/290878823661)
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A standard Craftsman 1/2 or 9/16 (can't remember) will do the trick. Even Kmart sells those now.
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A standard Craftsman 1/2 or 9/16 (can't remember) will do the trick. Even Kmart sells those now.
9/16" I just removed the distributor on the 140 I am pretty sure that is the size