Ok while I've got my motor out I thought about changing heads. I've got two sets here ready to go. Which would be better ?


Sent from my iPhone using SoCal Jet Boats

Dude.... Stop.

You have two completely different heads there.

396 closed chamber and 454 open chamber.

What are you building? What pistons? deck height?

You cannot just willy nilly interchange heads because you have them.

There is a wee bit more to it than that.   

GT

Lol I've got a pair of each



Sent from my iPad probably bored at work! Lol!

Not the point.

If you put closed chamber heads on an open chamber short block combo, the 13.5: 1 compression ratio will run like a raped ape, for about two minutes...

If you go open on a closed, with the low compression ratio you will need a blower to make it run.

What do you have for piston, block, crank?

GT

3856206, 65-66, oval, CLOSED, 396, 97cc chamber


6272292, 70-78, oval, OPEN, 402, 454, 110cc chambers. (edit;) BTW, the 110cc portion does not seem to be published, had to do a little research... 

Ok, so maybe not as as extreme as the last post, but completely different heads. I think you may have a quench deficit on the 292 heads...

They are 402 heads... (oddballs).

What motor do you have?

GT

It's a bone stock 454 indmar with peanut heads.


Sent from my iPhone using SoCal Jet Boats

Leave the peanuts. They run quite well for a stock motor. Those other heads will not work.

IMO.

GT

Hmmm, an 8.2:1 C/R motor w/ 122 cc chambers would not benefit from a smaller 110cc or 97 cc chamber? Especially if the peanut ports are the non adjustable valve train?

I'm running 100 cc 427 heads, stock size valves, on my 454, +.030 over, with a trw forged flat top type piston, and its at 9.07:1 C/R
And a lil econo roller cam.

Will not work...I dont know
worth a head swap? maybe not

Dan'l

Not going to get into a pissing match again, but a 4.1" bore Vs. a 4.25" of the 454...

Go for it.

Without some work on the chambers, these heads will not work. There will be quench issues as well. The gains would not equal the work.

IMO

The 427 heads are a great choice, they share the 4.25" bore size of the 454. edit; you have not a clue what pistons are in the motor without pulling the heads. If it has domed pistons, it will run for three revolutions.

More info is needed before you can say "bolt 'em on." Don't think the half point of gained CR is even remotely worth it.


GT

Skipping the head swap. Thanks a lot. I'll be boating tomorrow.


Sent from my iPhone using SoCal Jet Boats

That motor will run literally forever with those heads. It does not make enough HP to kill itself. (like in the realm of 330 HP).

Find another engine and build that then it is just a simple swap. If it truly does have peanuts, it will be a truck crate motor, cast crank, cast pistons, passenger car cam. Literally nothing in that motor is special. Trying to get more HP out of it by swapping to oddball heads without pistons, camshaft, improved rocker arms, would be like putting perfume on a turd, sure, it will help in the short term, but it still be a piece of crap.

No offense intended and I see what you were trying to do, but it would have been all for another maybe 50 RPM..

Get your temperature and carburetor issues sorted out and have fun. You have too much other crap going on with that deal.


mash on it, I meant no disrespect to you. When I said it wont work, it will run, but without way more information, I felt like it would have been a huge error to swap from one set of heads to another when it don't even run to start with. See what happens when I don't write a hundred words?

Please accept my humblest of apologies.

GT

I have the same problem. I have the same motor in my boat. I want more HP only thing I'm doing to mine is changing the intake manifold and the headers just for the looks. Gonna build a new motor over the winter.


Sent from my iPhone using SoCal Jet Boats