[Jay S]

I am curious what pistons your engine has. I played with the numbers some and there was a little more difference in the pumping numbers than I would generally expect from the 62 to 6X-4 swap. Could be several things that influenced the pumping test though.

A cam that is little bigger than the low 220s would be better, it needs enough lift to get into an area that it uses the head flow better. A summit 2802 would run ok, but not my first pick. (224*/234*, .465”, .487”, 114* LSA, 109* ICL). I think 228* @.050” on the intake would run better so you can get the lift closer to .5” lift. You could go bigger yet if you were willing to run a Rhoads lifter or a HLJ R lifter. Something like a Crower 60243 would work with Rhoads. Without Rhoad's I think the Crower cams would run better in the low 220s, pretty much like your thinking.

There are better options than the Summit or the Crowers, a Bullet Racing cams H278/330C (228*@.050”, .495” lift) on the intake paired up with a Utradyne H32, 286*, 238*, .5” lift on a 112” LSA with the ICL on 108* would not need Rhoads, pump about 160 psi, idle pretty smooth, and run on a point or two lower octane than your Engle cam, it would make a lot more power. I would probably suggest the older Ultradyne 288/296 grind or something with a bit more seat timing from Bullet when using a variable duration lifter. Maybe even a couple degrees bigger, that could get it closer to 450HP, on 87 octane.