1972 Demon 340 engine mods

OK so I took the heads off and found strange flat top pistons with 4 big valve reliefs at zero deck.
Pistons are not completely flat and reliefs + area around bore gives me bit over 10cc. This added to 8.8cc for felpro 1008 head gasket +63 cc heads gives total 81.8cc so 9.5:1 compression.
Piston will be head gasket away from the head so 0.039" and I guess I don't have much room here.
Another discovery is Mopar purple camshaft .484" lift and 241 duration @.050 which added to no low end power nicely I guess... We will be using 1.6:1 rockers so lift will be just over .516". J heads from the car have small intake valves.

Cam swap coming soon.


Why change cams? If you need more cotton add some compression. That cam is not big. BTW, the piston needs to come out of the block. Factory MINIMUM is plus .017 and you can stick it out more.