How many miles on the engine?

The 454 is a great base for a jet boat engine, relatively cheap to add HP, and for the most part reliable. I'd say you'll be fine with it in stock mode.

Comp Cams XM278H grind with matching springs and you're in business.

I would upgrade pushrods aswell and maybe some nice roller rockers

You may want to take a peek at what heads are on there. Just a thought

why?

Cuz a smog head ain't gonna flow as good as an earlier one.

can i interchange?

I am not the guy to talk to about anything Chevy but I would venture to say yes.  They have been making mouse motors for a loooong time.   GM's only good product really.    Save it haters, I call em as I see em.

Well the ZL-1 was a good try too!

i work for ford, chevy is cheaper for my situation.

You're the expert but I think that if I were trying to build less than say 550 HP as cheaply as possible to last as long as possible,  I'd build a stroked 400 Mopar.  My last one made 550/550 with small valve heads, stock rods, crank, block, mech. cam.   No porting, no trickery.  Only real money was spent on pistons.

I know that won't go in a boat though 

Hey Doc  check your PMs
I don't wanna jack this thread any further than I already have

ok picked her up tonight, here are the numbers tell me what i have?
block says pass hi perf, cast 14015445     gm10t     08 68 it looks like, head castings 346236, what is this stuff interchangable and is it ok to start with un molested

ok picked her up tonight, here are the numbers tell me what i have?
block says pass hi perf, cast 14015445     gm10t     08 68 it looks like, head castings 346236, what is this stuff interchangable and is it ok to start with un molested

You got good stuff there IMO, are you even going to freshen things up, or run what ya brung?

346236.....75-87...oval...OPEN...454, 120cc chamber, 225/116cc ports

-beerjet-

Not to mention a possible four bolt 454...  

going to take apart this weekend, i think i am going to hone and rering, do the heads, cam, roller rockers, tunnel and single 850, what do you think

Works for this whiteboy...

But will throw at you, new oil pump and pick up (cheap insurance) and change out the freeze plugs, probably steel right now...

I love grenade motors (motors with as few new parts as you can get away with....They run the best..

oh yes i am going to put in new freeze plugs and, high volume oil pump for sure. i wouldnt f around any other way. is the cam recomended above a good choice? any others

If you are asking about a comp XM 278, yes, great choice actually....I have one sitting on the toolbox..Racey idle, runs pretty hard and like headers...

I'm not real hit in the head about the high volume oil pump though...cavitation is common, the motor will almost always run at 3500 RPM or more and IMHO is not needed...Get a standard oil pump and detail it, you will be better off (again IMO).

GT