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CVX-20s info ... (And other Glastrons)

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Better engine mounts for CVX-20s (And other Glastrons)

Before getting to this subject, I just want to say...If you read this and have either a better idea or something to suggest, please do...I have a bruise on my forehead from slapping it when someone has looked at my "Great ideas" and then suggested something simpler/better- I need to keep that bruise going because it is my signature look!

When I had my engine rebuilt the first time in 2003, I installed a full-length 10-QT Milodon oil pan because I don't like the front sump Ford pans...They are not so bad in a car (At least an above 13 second car) but in a jet boat you have good-to-great acceleration coupled with some bow rise- this can starve the engine for oil under acceleration.

(Note; I have seen bad reviews for the Milodon pan, but mine fit well and has worked great for 17 years...There are other options, including Canton) I also used the late-model all rubber one-piece gasket- I had to drill out the corner holes for the older larger bolts; Two pieces of 1/4" aluminum plate, drilled for the larger size, plus two holes for clamp bolts- then clamp this fixture (Tightly!) on the gasket to keep the metal bushing INSIDE the gasket from spinning while you drill it out to the larger size)

The problem with a full-length oil pan is that the engine mount set-up for Berkeley Jets has a crossmember that will interfere with the pan. If you only cut it out then this will put more stress on your stringers. I have designed a solution- actually two solutions that really improve the strength of the whole setup.

First up was clearing the pan- that crossmember had to go but I wanted to still have a cross-brace. I picked up a piece of 1/4" steel that would fit between the front and back verticals of the engine mount bracket, then curved it so that it would start at one side, curve under (The oil pan) and then come up the other side (See Diagram). It was not as rigid as the (vertical) original crossmember but better than no cross-brace. After having the piece welded in I cut out the old brace.

This worked for 3 years just fine.....But when I needed the engine rebuilt again (Bad head work when I had a "Friend" port the heads which caused a valve to seize out in the Delta(10 miles home on 1 cylinder bank) I decided to up the ante!

A lot of hot boats are converted to a "Rail mount" engine mounting setup. You bolt a long piece of aluminum angle to the stringers, then cross-members at the front and back of the engine tie together to make a rigid mounting that can handle any amount of power.

But the CVX-20s have a floor on top of the stringers which limit the amount of stringer that is accessible for such a system.....I had to think about this; Gears grinding....smoke out of ears......And a new idea came into being- a Mini-rail system!

I picked up some 1/4" thick angle iron and cut it to fit on TOP of the stringer in that small exposed section, then I used more angle iron to replace the 90* pieces that go between the crossmember and the stringers(Rails) Critical to good strength and rigidity of the setup was that instead of SLOTTED adjustable holes (To fit multiple boats) I drilled the holes in the 90s to exactly fit my engine mount dimensions- so now it is rigid....even if the bolts were a little loose there is no flex or play in the set-up(And no twisting force applied to the stringers).

When I mounted those rails on top of the stringers I mixed up some resin with micro-balloons and cut fibers to make a putty that I put between the top of the stringer and the bottom of the top of the rail- that way the weight load is spread evenly on the stringer (Most of the resin-putty will squeeze out but what's left will even the surface out). I also used the original little plates that were on the bolts thru the stringers; The stringers and fiberglass had taken a set during the manufacturing process so the little plates fit- trying to make it smooth would have taken a lot more work...although it is not particularly pretty, I defy you to find someone who will stand on their head in the engine compartment with a flashlight clenched in their teeth to see those little metal plates!

Depth-finder GPS Speedo install 

Years ago, I was out in the Delta in late October- checked water temp with a thermometer; 60*...The next week we had a cold snap- but on Thursday I checked an online reading which was at 57* (My waterskiing cutoff was 55* back then(With a wetsuit- I am not a complete idiot)...So Saturday I jumped in the water for my ski ride- and could hardly stand it! Had to keep looking down at the ski to see if it was still there (Could not FEEL it!) When we got to Skye's beach I checked with the thermometer and it was 52*!!!

Because of the silting of the Sacramento Delta, there is more and more chances of finding a sandbar, so I figured I could kill two birds with one...electronic device. Specifically, a Hummingbird 176i. Depth gauge, and also Speedo and water temp readings.

I did not want it (Always) sticking up on the dash of my sleek hot boat, so I mounted it on a hinge so it would fold under the dash- I have some sort of a clip device (Possibly off an aircraft) that holds it tight under the dash, and just use a mini bungee cord to hold it up in readable position...Not completely elegant but it works.

Also, I have compared the speedo function with my original 1977 speedo, and amazingly, that old pitot system is pretty accurate- from 25 mph up to 60 it is right on the button!

Building a better 460 and Berk jet for our CVX-20 jets

For years and years I have had people tell me that Jet boats suck a bunch of gas- "Your jet uses 2-3 times as much gas as my Malibu Skier!" I kind of had doubts about this right off...One of the most obvious causes of my doubts was that 90% of the ferries in the world use jet drives- Some of this is because of lower maintenance and not having anything hanging down to damage if you hit a reef or beached- but if they really used that much more fuel, no way would 90% of Ferries be jets!
I found a Powerboats magazine test of my CVX-20 that showed it getting 3.2 mpg at 30 mph.....DD Ski boats were getting 3.3-3.5, depending on engine size and boat weight.
I also had been surprised by GM building a pushrod engine after Ford had come out with their DOHC 4V V8 engines...I thought that GM would get their collective butts kicked...And then I started seeing comparisons between 1998 Mustang Cobras and Camaro SS...The Camaro was quicker and got substantially better MPG...What the heck? I thought the 4V engines were the Shizznit!
My 460 took a dump and I needed to get it rebuilt- I talked to a couple of friends who had a machine shop- Wade and Jimmy at "Al Hubbard Marine" in Hayward. They were very cool and did regular engine rebuilds plus all types of more exotic stuff- Sleeving blocks for #s matching restorations, building up hot engines for actual racing cars and boats- They knew what they were doing and did it well.
I found out from numerous sources(Including Wade and Jimmy) that those GM LS V8s had numerous technological advancements- 1) Tight Quench; Quench refers to the flat top of the piston coming close to the flat part of the head- It creates turbulence in the combustion chamber, mixing the fuel/air (And flame front)...Also, the HOT piston transfers some of it's heat to the (Water-cooled) head. All together, this allows leaner mixtures and higher compression ratios. (Four-valve engines cannot make good use of the Quench architecture- There is no room in the combustion chamber because of the four valves)
Also, 2) The cams in the LS are relatively hot, but contrary to old school "Hot" cams, the lobe separation (Degrees of engine crank rotation between the exhaust and intake cam lobes) is wide rather than narrow; Narrow creates a lot of Valve overlap and gives you that rump-rump idle while upping the HP at high "R"s...But the engines would run like pigs below 3000 rpm. By spreading out the lobes (From tight 106-108 degrees to 113-118) you gain a lot of low end power and the engine runs good from idle up to say 5-5500 but you lose approx' 5% off your top end power above 5500. Critically (For this article), the engine will run more efficiently at cruise rpms (2000-3500).
I had Wade "Deck" the block (Machining off the top to make it flush with the piston tops) This made the "Quench" measurement equal to the Head Gasket thickness (.039")...I bought Keith Black Hypereutectic pistons that set the compression at 9:1- that is high for Regular gas (87 octane) but with the good quench it has not been a problem.
Note; I cannot state the right pistons for YOUR build because the 460 heads vary in Combustion Chamber size....Mine were D3VE A2A castings, but even these can vary from 92 cc to 97 cc- You need to have your heads CC'd to make sure. Then buy pistons with the right amount of dish volume to get your comp ratio close to 9:1....(CC the combustion chamber, then; Chamber CC (x) + Piston Dish CC (y) + Head Gasket CC (z) then divide that into your swept volume will give you your Compression Ratio. Mine is x = 92, y = 5, z = 10 for a total of 107 cc = 6.53 ci divided into 58.54 = 8.96:1 compression ratio- (My bore was opened to 4.4" and the stroke is 3.85")

Page #2

I  had the Heads ported a bit on the exhaust side- They have a port for a smog pump- The Marine engine does not need these ports- they are in a large bump which cuts down on port flow, so simply grinding these down will improve the exhaust port flow.

I had a custom Cam created at Comp Cams (Does not cost any more than a listed cam)....It is a .495/ .510 lift (At the valves) and duration of 219/224 (At .050"lift) and lobe separation of 113 degrees. I used regular lifters and rockers.
Added note; I forgot to mention that the Timing chain setup on our engines in stock form is a retarded "Smog" setup; When rebuilding get a normal "Straight up" timing chain set and that alone will net you approx' 30 hp right off while making the engine run cooler.

As I assembled the engine I decided to use the Weiand Stealth dual plane manifold- Dual planes basically separate the V8 into two 4 cylinders, which improves the fuel-air metering- but the old Dual planes were basically torque intakes- lately, the major companies have been making large-passage dual plane manifolds. Edelbrock has a very good one (Performer RPM) but the Weiand Stealth is both less expensive and actually seems to perform better. (Note; Edelbrock makes a Air Gap manifold which costs a lot more- It does have some benefits in a car, where you get airflow in from the radiator opening to cool the manifold- but in a boat engine compartment there is no airflow to use for under the manifold)

One of the biggest design problems in any of the Ford (Marine) engines is that the oil pan has the sump at the front- this means as a boat accelerates (Accel "G"s plus bow-rise) the oil surges AWAY from the pick-up. So I used a 10 quart pan from Milodon. Instead, you can buy a REAR sump pan- on Amazon it is only $166. Although this is not a Marine pan, the original pans are just stock truck pans- no special treatment.
(Because of my 10 QT pan I had to redesign the engine mount cross-member and ended up making a mini-rail mounting. This should not be necessary if you use the rear sump pan ) Additional note; The rear sump pan probably won't fit- would hit the bottom.

The last detail of the engine build is the Carburetor; I decided to use an Edelbrock 750 Marine Carb. The nice thing about the Edelbrocks is that they are tuned by changing components- not by adjustment screws- With a Holley you usually have to adjust it every so often- I have not adjusted the Edel' after I set it up...That is 14 years of running- basically 1-2 hours for 20 weekends during the summer plus another 20-40 hours during my boat camping trip at Trinity each year....Approx' 6-800 hours of total time. I have changed the fuel filters- both a course plastic filter and a fine metal-matrix filter- a few times tho.

Next up the special tuning of the carb......

Page # 3

For my CVX-20 Jet boat I set up the Edelbrock carb a little differently than is typical. I leaned the carb out two steps in the midrange; Think about how you usually find out your engine is running lean- You pull hard at a low RPM- say put your car in third at 20 mph and floor it...Then the engine will ping- Pre-ignition, which can damage your engine, so you then richen the mixture.

But a Jet boat is a different; You're at idle, and you hammer the throttle- What does the engine do? It immediately goes straight up to top RPM....You cannot "Lug" a jet boat, ever!

So I leaned it out down low, which gives me much better fuel efficiency at 2500-3500 RPM cruise, and then I richened it up in the top end to make up for any transient lean condition- I also set the accelerator pump at it's highest setting.

Now you may be saying "Sounds good in Theory- but what happens in the long run? Will that lean condition burn the plugs, rings, valves, etc?" Well, I made these changes back in 2003...So I have been running the boat this way for 14 seasons...And just decided to have the carb cleaned, and while that was going on I pulled the plugs and inspected them- They looked great to me, but I decided to back that up with 2 different friends of mine looking them over also- All three of us basically stated"They are fine- almost look brand new" I actually re-installed them. (I had spent some time clocking them back in 2003, so I didn't want to change them if not needed.)

With the cleaned carb, the boat runs like a tiger- the last two years it was a bit hesitant on start-up and actually back-fired a few times. So if you do this set-up, just clean the carb say every TEN years.......

Next up, what I did to the pump.....


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