Too high compressionJuly 10 2012 at 3:33 AM
Barry R (Login Barry_R)
Response to Compression calc please
The compression is simply too high for the short duration cam in a heavy car with modest gearing. It would've worked OK in a Cobra or Mustang. If the heads are coming off I would first do an actual cc check - and then do some chamber relief work around the valve sides and the deeper side of the chamber wall to see if I could grow that volume a bit.
A cam change would help. The earlier Crane hydraulic rollers were pretty abrupt - short duration and high lift. Made for lots of cylinder pressure and torque - but very fussy on valvetrain and fuel sensitive. A cam with more duration might allow you to run more initial timing - total should still be no more than 36-38 - and in turn still feel decently strong without sacrificing lower end power. I agree that a cheap fix effort could be retarding the cam a couple degrees - but suspect it'd want more initial advance as a result and you'll end up in the same spot.
- Re: - Charlie on Jul 10, 2012, 4:43 AM