[Douglas Willinger]

I myself am intrigued by the idea of using the higher compression round-port heads, either the 1968 "96" Ram Air II or the 1969 "722" or 1970 "614" Ram Air IV heads on a 4" stroke.

Originally Posted by Formulajones

That idea works but still doesn't bring the compression up enough, since the chambers in the heads are so large.

Even at zero deck (actually we had the pistons .007" out of the hole) and the HO heads were milled down to 107cc or somewhere in that area (again paperwork not in front of me) I had to use a .045" gasket to keep quench comfortable, and even with that dome on the piston that I pictured above the compression was still only 9.98:1. Take that dome away and you'd have to mill the crap out of the heads to get it back, so far to the point you'll be cutting intakes to fit, valve clearance and geometry becomes an issue etc...Not to mention a set of expensive factory heads that have now been chopped so far they sort of become married to that combo and not much good for anything else.

There is nothing wrong with using a domed piston in a Pontiac as I and many have shown, it works if done properly. Chevy used them all the time. There is something to be said about flat tops and flame travel for sure, but a dome isn't going to hurt anything if the rest of the combo is chosen well. Here's a shot of the narly dome used in my DZ engine. These are NHRA legal reproduction from JE to produce the factory 11:1 compression this engine originally came with, compared next to the original OEM TRW piston that came out of it.

I run an LS7 dome piston in my 454, which is quite common in the BBC world because cylinder head chambers are also quite large for these engines.