Greetings,
Engine builder and mechanic telling me that this is caused by detonation at high RPM. Found rings broken on #5 cylinder, but piston does not look like this one.
Engine is a '78 Euro 3.0L with 3.2 cylinders and pistons built in 2009. JE 9.5:1 pistons. Currently the 964 profile cams and PMO carburetors (was CIS until a year ago). Lightweight track only car that sees 6,800 RPM (since the carbs install) a couple times each lap in 4th gear. Carbs recently tuned on dyno and set a little rich. Track is within 1 mile for the dyno station. No wide band....I know I know....
So now what? A costly rebuild for sure. GE60 Cams with correct 9.5:1 pistons? heavy springs such as Eibach pro series? Would like to stay with pump fuel for obvious economic reasons. Builders are saying "yes"...this is possible on pump fuel.
I stick to busy stations that sell Chevron or Shell. I suppose it possible I bought a stale batch. Are these octane boosters for real or are they just the typical marketing BS. If so, which one is best.
Also....what is best wide band to purchase and the best configuration for a carburetor engine with discrete headers
Thanks
