Chevelle Tech - View Single Post - Lean at High RPM
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post #1 of (permalink) Old Mar 25th, 20, 7:51 PM Thread Starter
Tech Team
Join Date: Aug 2001
Location: Belvidere, IL, USA
Posts: 212
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?


Randy Johnson
70 Chevelle
[email protected]<
1.766 60 ft

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