I have a 454 with 236(? I think that's correct) peanut port heads. I want to run this motor in a Sanger Hydro boat while I gather up enough cash to redo the motor. I have a set of stock configured oval port 781 heads available to me for free. Will these heads work without changing pistons? Which way will the compression go? Up or down? I don't know much about the internals of the motor (cam, pistons, etc.). Cam is a hydralic flat-tappet though. I do know the motor ran when I pulled it from the truck I bought that had it and it sounded real good.

I realize this isn't Chevelle related, but I think you guys can help me out! Any help for a budget Hydro motor with the parts I have available would be appreciated. I want to run a tunnel ram too, so keep that in mind. Thanks!

Alan

Alan,

If those are the 236 castings, they should be open chambers, same as the 781's. I think all peanut port heads were open chamber, but I'm not positive. :confused:

Both chamber size should be close to the same give or take a couple of cc's. I have checked a few sets of 781's are they were all around 120-122cc.

CR shouldn't change much, if any.

Here is a link to a site that has all the info on big block heads and other engine componets.

http://www.mortec.com/castnum.htm

Cool, thanks guys. Looks like I will gain just a little compression as 781 heads are 118cc chambers and 236 heads are 120cc chambers. Perfect. Now I know what I need to do.

Thanks!

Alan,
Those 781's are going to breath a little better also.

Originally posted by SS_Dave:
Alan,
Those 781's are going to breath a little better also. Oh yeah! Exactly why I'm going to dump the 236's. It'd be no good having a boat motor running out of breath at 4500-5000 rpm, ya know smile.gif . I need to turn at least 6k. Hopefully I can build a decent running budget motor for the time being. I'm iching to get on the water! Thanks for the reply Dave!