Question on D3ve a2a's (and other crap)
 

I've been looking around on the net to see if I can find out what size the combustion chambers are on my D3VE-a2a heads are. I've found some conflicting numbers and I was wondering if anyone here could tell me for certain what size they are. I've found 92cc 95cc and 97cc. I'm assuming that all the heads with this casting are the same combustion chamber size. Is this where I'm making my mistake? I'd think that this casting would be all the same chambers.:-? (BTW I did find a reliable source citing 91.4cc's, which I'm inclined to believe)

....and could someone guess (I know there are a ton of variables) at what my CR would be with these heads. The 460 block and the heads have not been decked, the pistons are KB hyper with 2.5cc valve relief flat tops, nominal head gasget.

....and finally, is there a reliable correlation between PSI reading on a compression test to CR. I know there is a correlation but can you get an idea of what CR you have with the PSI number. My compression tests yeild approx. 180 psi on all cylinders. I know you can't just divide by 14.7 to get approximate CR, but am I missing something?

The reason for all the dumb questions is that since I've gotten this motor I've assumed it was running around 10-10.5 to 1 CR, but I'm thinking more and more it's more like 9.5 or so. I'd like to put some DOVE heads on her but if she's at 10-1 now, DOVE heads would put me way above a pump gas friendly CR.

In any case, I'll be tearing into her pretty soon. I think I've spun a bearing in her and now it's time to yank the motor and rebuild her. I've heard good things about the D3 heads but if I can get some more hp I like to plop on some Dove's. As long as pump gas will still be useable. I've checked the specs on the cam that the guy that built the motor put in and it turns out that it is a symetrical cam. I know that the 460's like more dur and lift on the exhaust side to make up for the ****ty exhaust ports. If I do stick with the D3's I'll be grinding the smog bumps off in the very least, and probably do some clean up but nothing crazy with the ports. This motor goes in a jet boat so I can get pretty crazy with cam profiles and get away with it. Don't have to worry about idleing and such. :spin: I'm not sure how crazy I'm gonna get with her just yet, I've toyed with the idea of stroking it, but not sure I wanna stop at EVERY gas pump on the lake throughout the day. She runs real strong with a 750 holley and nice and reliable. Besides I'm reasonably sure it's a '79 block (and yes it is externally balanced crank) and I don't see a lot of stroker assemblies designed for my app. This will all depend on what I find when I open her up. I'll see what all went south and work my way up from there. :)

Nick

I use 95cc has an average. Because of casting quality control it tends to jump around a little. But with the info you have provided, your c/r is 9.6-1. Throwing a set of D0VE's on there will make that 11.5-1 all things being equal.

I think 11.5 is a bit too high for running on the river. With timing adjustments and good fuel it wouldn't be a problem, BUT it's not too rare that I need to fill up at pumps on the river and they are usually 91 octane or 89 octane. So with that in mind I think I'll concentrate on gettin more ponies despite the lower CR. I'd rather run a too low CR than too high. Thanks for the input.


Nick