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webfoot · 11-23-2011, 03:10 PM

I have not seen mention of what kind of cam you are running. Performance cams with lopey idle can benefit from the manifold vacuum to keep the vac signal up high enough where the advance kick in and helps it idle. With stock or stock-ish cams the extra vac at idle is not needed so ported vac is OK.

11-23-2011, 03:10 PM	#25
webfoot Registered User Join Date: Nov 2007 Location: Hermiston, OR Posts: 947	Re: Truck won't start right up and backfires like crazy! I have not seen mention of what kind of cam you are running. Performance cams with lopey idle can benefit from the manifold vacuum to keep the vac signal up high enough where the advance kick in and helps it idle. With stock or stock-ish cams the extra vac at idle is not needed so ported vac is OK. __________________ *Running in place gets you nowhere fast.* -me 1968 GTO 4-spd covnvertible 1970 K-20 4-speed, factory AC.