Join Date: Aug 2001
Location: Belvidere, IL, USA
Lean at High RPM
I have a 496 with a mild cam. 10:1 compression. Rebuilt Holley 850 double pumper. I am getting popping/misfiring above 5000rpm and high load. Getting sufficient fuel pressure with my electric pump.
I have a wideband in one bank of the exhaust. It is going lean at higher RPM. It's hard to tell at WOT, but at part throttle, it gets to almost 15:1 above 4500rpm. At lower RPM, it is around 12-13.
Went up 4 sizes on secondary jets. Did not seem to help.
Running 6.5 power valves. Will going to 4.5 help?
What else should I try?
1.766 60 ft
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