Valvetrain noise or detonation?

jeffnoel

Founding Member
Aug 31, 2002
1,638
5
37
Clovis, CA
I istalled a set of rebuilt E7s from a 90GT on my 78 302, they have the same valve size bit a 64cc chamber compared to the 69cc chambers of my 78 heads. Both heads use pedestal mount rockers. I picked up a set of Crane 1.7 rollers and installed them along with the E7s and a new Edelbrock Performer flat tappet cam with new lifters and push rods. I have gone through and adjusted the rockers twice per the Crane Cams instructions (link). But I'm still getting some noise when accelerating. I'm running 12 degrees initial advance and I've tried 10 and 14 but 12 seems to be were it revs and starts the best.

Am I wrong in thinking that if this was a valvetrain issue it should make the noise all the time not just under load? Again when sitting in the garage and giving it gas it revs nicely with no noise and with a light on the timing marks it moves smoothly and doesn't bounce around at all. But put it in gear and under modest acceleration I get this pinging or valve clatter like I used to get in my old Fairlane when trying to accelerate up a steep hill in the wrong gear.

Any help would be appreciated.
 
  • Sponsors (?)


I'd venture to say you have some detonation.

Small exhaust leaks do sound like that sort of, but since it happened after just the valvetrain upgrade, I would think detonation.