Author Topic: Carb & ignition probs  (Read 6061 times)

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Offline DanR

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Carb & ignition probs
« on: July 18, 2010, 12:06:44 AM »
OK, it's not on my CV, but on my dads Silverline. it a 1981 with a Merc 228. It's been not wanting to idle since he bought it last year. We use a kicker motor for trolling so it hasn't been a big deal. Well, Friday it died comming into the launch and wouldn't restart. I had it lined up pretty good, we drifted up to the dock better than ever. Nobody even knew we weren't under power.

I changed the plugs, they looked great, but changed them anyway. The fuel filter was a bit dirty, changed that as well. It ran good in the driveway, so I packed up the timing light and a tach to hook up for ease of seeing it back by the motor and went out for some night fishing. The manual says to set timing to 8*btc idle @ 650rps while in the wate, in gear, throttle cable removed from stud. Well, I got the timing to 8*, was @ 11*, and the idle down to 700. Any lower and it'd die. I started to adjust the port side idle mixture screw on the Quadrajet. Turning it in, it started to run a bit rough, so I noted that at 2.25 turns from seated. I then started to back it out. At 2.75 turns, it ran as it always did. Now, I expected the rps to drop because of a rich mixture at some point, but I can turn it out up to 12 turns without any change. I set that one back to 3 turns and went onto the starboard mixture screw. It acted the same way, only it lost some rpm's at about 2.5 turns. I know the answer is to rebuild it, but was wondering if an Edelbrock or Holley wouldn't be a better choice for it. I keep hearing horror stories about Quadrajets.

 I didn't even bother looking into the ignition yet. While adjusting the timing, evey once in a while #1 wasn't firing for 1 or 2 revolutions. I did put in new plugs and wires this spring, it has the petronics in place of the points. Some time after it gets a bit less muggy here, I'll pull the cap and replace. I just figured I'd throw that out just in case somebody can let me know what else I can look into if'n that's not my problem.

The curse of the Salmon-A-Rama still holds. My old boat crapped out on me every year at some point during the contest. Now his crapped out.

On a side note. At least I don't feel too bad, there's pretty much no chance on catching the biggest fish. A guy fishing about 200 yards from us cought what could be the world record Brown Trout.

http://dev.www.jsonline.com/blogs/sports/98619539.html

1974 CV16
2001 GX205
1978 Venture bass boat

Offline Rich_V174SS

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Re: Carb & ignition probs
« Reply #1 on: July 18, 2010, 12:24:48 AM »
I've run across something like this before. First a question - with the installation of the Pertronix where on the engine did you connect the red (positive) wire that comes off the sensor? If you went to the (+) terminal of the ignition coil that's a no-no because you're tapping power that has been reduced to 8-9 volts by ballast or resistor wire. If that is the case the engine will probably stumble if you hit the trim button for the drive, less power for ignition. Make sure you tap power at a 12v ignition source in-line before the ballast or the engine may miss if the Pertronix is not getting full power. If the distributor cap hasn't been changed in a while I would change that and the rotor. Rebuilding the carb will most likely make a difference too if the idle mixes don't affect it turning them all the way out.
« Last Edit: July 18, 2010, 12:26:49 AM by Rich_V174SS »
1967 V174 Crestflite SuperSport Modified
1987 Mercruiser 190 3.7LX/Alpha One

1970 V176 Swinger
1983 Mercury 115

Offline DanR

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Re: Carb & ignition probs
« Reply #2 on: July 18, 2010, 01:04:41 AM »
The Pertonix was on the boat when he bought it, I'll have to look at where the wire is attached. Thanks for letting me know about that! It may wait til I'm back from Arkansas, it's supposed to be either real hot and muggy, or raining til we leave. I don't want to work on it in either condition!
1974 CV16
2001 GX205
1978 Venture bass boat

Offline MarkS

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Re: Carb & ignition probs
« Reply #3 on: July 18, 2010, 03:49:04 AM »
Quote
Now, I expected the rps to drop because of a rich mixture at some point, but I can turn it out up to 12 turns without any change. I set that one back to 3 turns and went onto the starboard mixture screw. It acted the same way, only it lost some rpm's at about 2.5 turns. I know the answer is to rebuild it, but was wondering if an Edelbrock or Holley wouldn't be a better choice for it. I keep hearing horror stories about Quadrajets.
Hope you don't mind my throwing in my two cents worth Dan:
AFTER you check on the ignition stuff, I would definitely either get a kit and go through the Q-jet, or have someone rebuild it for you.  The Q-jets are much more complex (seems like hundreds of little parts!) than the Holley, which is a big part of their bad reputation.  Sounds like yours has some gunk build-up or trash in it.  If they're rebuilt properly, they're a good unit.  The Holley's were easier to work on, and had more parts available for "hot-rodding".  I don't have any experience with Vic's stuff (Edlebrock), but the quality of their product line in general has always been first rate, IMHO.  Either would be a suitable replacement.  I know Holley makes a "spread bore" replacement so you don't have to change the intake maniflold, don't know about E-Brock.
Mark
1978 SSV-176

Offline DanR

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Re: Carb & ignition probs
« Reply #4 on: July 18, 2010, 11:53:49 AM »
Thanks for the input Mark. It's been a while since I've been into a Quadrajet, but I've done a few in the past. I guess I'll give the rebuild a try, but keep the Holley in the back of my mind for it. I don't want to replace the intack also, seems to be a needless expense, thanks for that info. That's what I'm looking for.
1974 CV16
2001 GX205
1978 Venture bass boat

Offline Eric_Michael

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Re: Carb & ignition probs
« Reply #5 on: July 18, 2010, 12:48:06 PM »
...was wondering if an Edelbrock or Holley wouldn't be a better choice for it....

Twice I have replaced quadrajets with Edelbrock carbs.  Both times the carbs ran amazingly well right out of the box.  No adjustment was necessary.

On my old '76 Buick Estate Wagon with a 455, I had to get a plate adapter in order to adapt the Edelbrock to the manifold.  I am not knowledgeable enough to know what a Merc 228 is, but I'll bet if it came with a Q-jet that someone makes an adapter plate for it if necessary.

The only problem I had was of my own doing.  I selected a 750 CFM Edelbrock 1411 for the big 455 in the wagon.  A great carb for a big block - IF it is a performance big block.  This was not the case for a mid-70's low compression emissions motor.  It ran great with my foot on the floor, but the other 99% of the time it was too rich.  I could not get it leaned out enough.  I ended up getting a 600 CFM Edelbrock 1406 to replace it.  That ran much better, but ran out of go at the top end (again, a driver not a track car).  That carb is now on top of a 350 and Edelbrock intake on my '57.  Still running the factory jets & rods and never needed to be adjusted.

-Eric

Offline DanR

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Re: Carb & ignition probs
« Reply #6 on: July 19, 2010, 08:43:53 AM »
Merc 228 = Chevy 305. I'm going to take the carb apart and rebuild it today. We'll see how that goes. If that doesn't work out, I think an Edelbrock 1409 with an adapter plate is in the plans. I talked to a few guys at the marinas and boat launch, most think the 1409 is the way to go. Going to get a new cap and rotor and rebuild kit for the carb today. I hope to have time to test it out before we leave for a week. We'll see. Thanks again for the input.
1974 CV16
2001 GX205
1978 Venture bass boat

Offline Eric_Michael

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Re: Carb & ignition probs
« Reply #7 on: July 19, 2010, 12:23:28 PM »
I forgot about the Edlebrock Marine line of products.  I believe the 1409 is the same carb as my 1406, just with a different finish.  The silver finish probably corrodes in salt air or something like that, hence the marine 'gold' finish.  I'll bet with a freshwater boat which does not live on the water, a 1406 will be just fine.

Just be careful with the aftermarket stuff though...  It starts with the carb.  Then it is the performance intake.  Oh, and don't forget about the hot ignition with the MSD box.  Pretty soon you end up bolting on blue bottles which say NOS on them....    ;D

Offline dorelse

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Re: Carb & ignition probs
« Reply #8 on: July 19, 2010, 12:41:29 PM »
Merc 228 = Chevy 305.

Isn't the Merc 228 the 350?  I have a 305 and the stickers on the Valve covers are Merc 898...
1990 Sierra 1700

Offline DanR

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Re: Carb & ignition probs
« Reply #9 on: July 19, 2010, 12:45:04 PM »
Well, according to the manual, 228=305. And as far as putting more go fast stuff on it, not gonna happen. It's a fishing boat. As long as we can get on plane to go 10-12 miles out, we're happy. The 15 hp trolling motor takes it from there.
1974 CV16
2001 GX205
1978 Venture bass boat

Offline dorelse

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Re: Carb & ignition probs
« Reply #10 on: July 19, 2010, 01:21:14 PM »
Well, according to the manual, 228=305. And as far as putting more go fast stuff on it, not gonna happen. It's a fishing boat. As long as we can get on plane to go 10-12 miles out, we're happy. The 15 hp trolling motor takes it from there.

Yeah, you get the 4BBL with 30 more horses...

898 = 5.0 (305) Chevy with 2bbl carb- 198 horse
228 = 5.0 (305) Chevy with 4bbl carb- 228 horse
1990 Sierra 1700