Small Hughes cam in 318
Stock pistons, no eyebrows, .046" in the hole. I've calc'd CR numbers with .027, .039, milling etc. I just found it odd that they would rec. that low a CR with that long a dur., (269* & 61* ABC) which then made me question what I was seeing on the degree wheel, ya know, was I reading something wrong? Anyway, it is what it is. Thanks guys.
Your thinking is right.
But ohhh, .046 down with a 3.91bore is 9.05cc
Wait start over; to get to 9.25Scr with a stock-bore 318 requires a 78.95cc total chamber volume. With the pistons so far down; A) you cannot get any quench, and B) staying under 78.95cc is very difficult.
So 78.95 less 9.05 leaves 69.9cc for both gasket and head. That's gonna be real tough with those heads. And furthermore those heads are probably more head,than a 215 cam can make use of; at least most of the time. So what are your thoughts on ditching them?
With Magnum heads at about 63cc, getting 9.25Scr is a bolt-on deal, with an .028 gasket.And the Magnums are the right size for the teener.
Alternatively,closed-chamber teener heads will put the torque back in the low-rpm, at the possible expense of some power at higher rpm.Many persons scoff at those small port heads, but I can tell you that I once put some teener heads on a 340 and it flew on the street, with 2.76s,cuz the Rs were in the working range of those heads, most of the time!
But IMO, the best solution is a zero-deck, tight-Q,design. I'm pretty sure you're trying to avoid going this far, so I'm not sure what the answer might be for you. I know what I would do. Those 9cc in the deck height are a real killjoy.