what is the deal with my 225 /six compression?

what is the deal with my 225 /six compression?

Bill:

Thanks for that explanation. Your comment in a previous note ("I ended up with same setting for intake and exhaust, some cylinders at 0.024” ranging up to 0.028” on one cylinder that was at 140 psi.") made me wonder about possible damage to the lobe due to missing the clearance ramp completely, and encountering a too-aggressive opening rate, once the wider clearance was closed up.

That was my only concern...

At 0.006 lift lifter crank has moved 20 degrees, at 0.010” 30 degrees, and 0.030” 50 degrees. By shortening ramp or increasing rate of lift I have shortened the overlap event that has been causing low vacuum and torque at low rpm. I have moved the torque curve down the rpm band a little, and clipped some of the high rpm breathing which makes engine a more drivable on street. This engine begins to pull at about the same point a stock slant gives up at 4000 rpm, and pulls hard to 6000 rpm. Last 1/8th run was 10.3 seconds @ 68.3 mph with 3.55:1 rear gear, this is where a stock slant is running a quarter mile off the show room floor.

I think and have been told I need more compression for this cam to perform. Calculations indicate 10.5:1 static would yield dynamic ratio around 8.1:1 which would allow tightening of lash to take advantage of long ramps and better cylinder fill on mid-grade pump gas. But, this is all way beyond scope of this thread, and I apologize for hijacking it.

Additional technical engine chatter on this topic can be found on /6 dotorg if anyone is interested in this stuff.