GM Performance crate engine questions

[Jet City]

I see on most of GM's crate engines they state "not for marine use" in the engine description. As I understand it, marine engines require larger piston clearances due to the lower block temps. I have also read that these engines are fine for marine use so long as the head gaskets are replaced with marine gaskets and brass freeze plugs are used, is this the case? What are optimum piston and bearing clearances for a forged piston marine engine?

[Dave C]

I used a 502 crate motor in a jet. It worked fine.
However when I assembled it I always use FelPro blue gaskets.
I now own a Mercruiser 502 and I don't see that many differences. Maybe the differences are so subtle we can hardly tell. The bolt on items (alternator, water pump, etc.) are specialized though.
Go for it. They are great values.

[Jet City]

Thanks Dave, unfortunately, its my uncle shopping for the crate engine not me, he smoked the engine in his 21' Hallet.

[SleekPanther]

My ZZ502 came with brass freeze plugs and stainless steel head gasket. I think they say not for marine use to protect their biggest customer, mercury marine.
Paul
.

[Tom Foolery]

It could also have to do with some of the accessories not being "marine" grade. Alternators with spark arrestors, marine carbs. Stuff you don't need to worry about in an open engine boat, but might want to consider if you have a closed engine.

[THE BOSTON SIDEWINDER]

ON ANY WATERS IN THE U.S. THE COAST GUARD EXPECTS MARINE PARTS ON ALL BOATS, OPEN ENGINE OR NOT. BE CAREFUL! THEY OR OTHER LAW ENFORCEMENT CAN TERMINATE YOUR VOYAGE (ON THE SPOT).EVEN IF YOU'RE NOT WORRIED ABOUT THE DOGS, IT BEATS DYING BECAUSE A SPARK JUMPED AND IGNITED SOME FUMES. I'VE SEEN IT TOO MANY TIMES TO TAKE THAT CHANCE ANYMORE!...BILL.

[OMEGA_BUBBLE_JET]

THE BOSTON SIDEWINDER:
ON ANY WATERS IN THE U.S. THE COAST GUARD EXPECTS MARINE PARTS ON ALL BOATS, OPEN ENGINE OR NOT. BE CAREFUL! THEY OR OTHER LAW ENFORCEMENT CAN TERMINATE YOUR VOYAGE (ON THE SPOT).EVEN IF YOU'RE NOT WORRIED ABOUT THE DOGS, IT BEATS DYING BECAUSE A SPARK JUMPED AND IGNITED SOME FUMES. I'VE SEEN IT TOO MANY TIMES TO TAKE THAT CHANCE ANYMORE!...BILL. the biggest one I see is people not using MARINE carbs. better hope that float don't stick. eek! I had a secondary float stick on me once and all I can say is by the time you smell it you have alot of gas in the boat and all over the engine. I was smoking too. I'm one lucky SOB. I have since invested in a MARINE holley. Oh and I have an open engine jet or else I probably would still be eating through a straw.
Omega

[Jet City]

My question is in regard to the long block, not the accessories. This will be going into a covered engine boat and will have CG approved marine carb, dist, starter, alt., fuel pump (with puke line), flame arrester as well as a functioning blower fan. So, what needs to be done to say a 385 fast burn 350 to survive the marine enviroment, are the piston and bearing clearances sufficient the way the engine comes? Should marine gaskets be used in place of the existing gaskets?

[Jet City]

SleekPanther:
My ZZ502 came with brass freeze plugs and stainless steel head gasket. I think they say not for marine use to protect their biggest customer, mercury marine.
Paul
. That is an interesting point SP.