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Pyrotechnic · 12-22-2008, 08:31 PM

I had this issue when I upgraded the stock cam in a my motor. The issue is not carb airflow capacity, the issue is that your primary fuel metering is too lean. You will need to find a larger jet, or get a small drill bit set and drill out the one you have.

Also, be aware that these cams will like more timing than a stock cam will. About 34 total is a good place to start. Setting your timing to stock specs will make the motor run badly.

The average Q-Jet will flow 750 CFM which is good even for a mild big block.

12-22-2008, 08:31 PM	#2
Pyrotechnic Registered User Join Date: Feb 2007 Location: Austin, TX Posts: 3,930	Re: Carb sizing question I had this issue when I upgraded the stock cam in a my motor. The issue is not carb airflow capacity, the issue is that your primary fuel metering is too lean. You will need to find a larger jet, or get a small drill bit set and drill out the one you have. Also, be aware that these cams will like more timing than a stock cam will. About 34 total is a good place to start. Setting your timing to stock specs will make the motor run badly. The average Q-Jet will flow 750 CFM which is good even for a mild big block. __________________ 1977 GMC Sierra Grande Last edited by Pyrotechnic; 12-22-2008 at 08:31 PM.