Camshaft Clearance Ramps

[Michael H.]

Re: Camshaft Clearance Ramps

Thanks Joe. Keep us posted. It's interesting that all of the GM dyno results show a definite HP reduction when the lash was set to less than .028". If I can find some of these sheets, I'll scan and post them.

[Joe C.]

Re: Camshaft Clearance Ramps

Mike:

I would like to see them! There is NO QUESTION that midrange power will drop off with tighter lash, but peak power?? Is it possible that the power peak moves higher by a couple hundred RPM? Please post and/or send to me if you can find them. Dyno tests don't lie, as long as the ONLY VARIABLE is lash setting.
What I said is subjective, of course. If there is a power dropoff, it might be too small to feel in the "seat of your pants".

Joe

[Michael H.]

Re: Camshaft Clearance Ramps

Joe,

I'll TRY to dig out the paperwork today, or at least this weekend. (may be heading back to Ft Lauderdale for a few days)

Also have more of the same GM/engineering dyno sheets from the 67-69 Z28 302" engines which used the exact same 3849346 cam. The HP/torque results showed exactly the same drop as lash was decreased. I'm pretty sure all that paperwork is here, not in Illinois, because I think I sent Duke a few copies last year.

If the power feels good with the tighter lash settings, it may be worth experimenting and driving the car for a few days to properly evaluate the change.

The "no ping" that you describe would be a result of the tighter lash settings because the effective low RPM compression ratio has been dramatically changed. (reduced)