Another cam question

[Cuda]

Any reversion issues with this cam? BBC

Intake lift- .527" Exhaust Lift- .544".
Intake Duration @ .050"-224Exhaust duration @ .050" 234
Lobe Centerline 110

The reason I am asking is these are GM crate engines. They say they aren't intended for marine use, but I think it may be due to a no compete clause with Mercruiser. They are a heck of a lot less money than other marine engines.

[turbo2256]

Head gaskets, ring gaps, freeze plugs, valve springs and cam may not be proper for marine use on these engines. Fresh water use might get away with it and inclosed cooling system might except ring gap cam and valve springs

[Cuda]

Here is a quote from a guy that has the ZZ4 in a 206 Formula.

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Actually a Z24 is a chevy cavalier I tink! A ZZ4 is a small block GM performance parts crate motor. Mostly same specs as a 1970 1/2 LT-1. Very cool parts for very little money. Cuda, the one thing to remember with this motor is that a ZZ4 has to be run in fresh water or with closed cooling. I run in fresh water only. Reason - aluminum heads and intake. As far as changes made it really works well in the marine world. Cam profile was ok but reversion was an issue. I needed to put headers and tailpipes on it. Went with IMCO polished "manifolds" and some custom tailpipes that dump water near the transom. After that, just installed all the mercruiser engine accessories: quadrajet, alternator, fuel pump, merc electronic ignition, power steering, starter, etc. Had to slightly tune the distributor and the carb needed a little going through. Not one problem. I ordered this boat from Formula with the "performance package" ( 2" higher X dimension and a 3 blade 23pitch cleaver.) With the 350 mag it ran 4800 to 4900 rpm and I saw around 62 or 63 mph. ZZ4 turns 5600 rpm and on a 60 degree day with 1/3 tank o gas, and a slight chop it does 72 mph or so. Total investment of $2850.00 plus tax on the motor (friend at GM) and about $1900.00 for the IMCO parts. And as long as you tell them your ZZ4 was installed in your 1973 camaro you get a one year warranty. These crate motors are really a total bargain.

[Rootsy]

aside from the corrosion issues marine engines run under much higher sustained loads than in an automobile... This causes a LOT of heat on the top ring especially. If the ring gap is not sufficient the ring will grow and close the gap to the point where it will butt... you then break the ring land and crown of the piston and score the cylinder wall and all kinds of other nasty...

marine engines have a larger ring gap factor... ALSO cylinder wall clearance is increased, even for hypereutectic pistons. Bearing clearances are not much different from an automotive engine though.

you also need severe duty valves again due to the heat generated by sustained loads...

as long as the valvetrain is matched to the camshaft charactaristics that should be fine.. BUT the camshaft profile may be such that the motor will want to WIND to make power and in most marine applications you don't WIND em out...

JR

[turbo2256]

I was looking at their offerings just the other night. Mostly compairing HP and Tork figures between there 350 and 383 crate engines. Having my own flow bench and having dialed in SBC stock and aftermarket stuff real well. The engine I would select would be the hottest one they have with the iron Vortec heads with a cam more like the ZZ4. Max flow with the Vortec heads out of the box peek right around 238 at .5 lift. The aluminum stuff have bigger ports and lower flow at .5 lift and below. Big volume ports require bigger engines or higher RPMs to get best HP levels. So in my thoughts a Vortec head 350 with similar to a ZZ4 cam would produce more Tork and HP tahn the ZZ4. Also these heads on a 383 stroker would only drop peak HP by 200 or so RPM.

As for your BBC I would go for a 114 ish lobe center .550 max lift and back off on the duration a pinch. f this engine has square port GM heads I would sell them to a car guy and go with some Canfield 305 or the 310s a Victor JR Style intake, and a 750 BG or better Nickerson.

[turbo2256]

Rootsy,
I have in the past used a few car engines in boats , first a 327 SBC in a Lyman 18", Just break them in real easy or what you mentioned happens. Oh the Lyman woody went 60 with singe quad 65 with dual quads but with duals ate more than twice the gas of the single so it stayed a single.

[MOP]

Not to sure how true this is but being as I have seen so many automotive head gaskets fail being used in raw water cooled marine engines it may really come into play. I was told years back that if automotive head gaskets are run with raw water cooling the gaskets can not withstand the water pressure, what I was told happens is composition gaskets wet out from the water jacket side making the gasket material between the metal go soft making them lose torque and fail. I tend to believe this as I have had a couple that when torn down there was no corrosion to cause failure. Should be food for thought, only use automotive head gaskets with closed cooling. The extreme pressures a head gasket is under in a raw water cooled motor can be 100+psi at high RPM, Big Griz gave an example of pressure build up as speed increased awhile back that had me in awe.

Phil

[Rootsy]

Not to sure how true this is but being as I have seen so many automotive head gaskets fail being used in raw water cooled marine engines it may really come into play. I was told years back that if automotive head gaskets are run with raw water cooling the gaskets can not withstand the water pressure, what I was told happens is composition gaskets wet out from the water jacket side making the gasket material between the metal go soft making them lose torque and fail. I tend to believe this as I have had a couple that when torn down there was no corrosion to cause failure. Should be food for thought, only use automotive head gaskets with closed cooling. The extreme pressures a head gasket is under in a raw water cooled motor can be 100+psi at high RPM, Big Griz gave an example of pressure build up as speed increased awhile back that had me in awe.

Phil

i've been using a lot of SS .015 shim head gaskets and rubber coated SS shims gaskets of late... it helps to get your quench wehre you need it. since i generally surface all of the blocks i do i can spec the finish and know it is flat as well as cut whatever i need to get the deck height i desire... I always give em 3 coats of permatex hi-tack spray adhesive sealant before installation... i have not had a failure yet... including my own mouse with stock deck height... if i cut em for zero deck height i go back to a .039 SS core Comp gasket...

as for rings.. we are only talking .004 inches extra clearance on the top ring...