The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 4 hole carb spacer for better signal, will it work?

Mike C · 07-01-2016, 08:50 PM

Backfire out of the carburetor is a lean mixture issue. Try moving the accelerator pump cam to the number 2 spot so it comes in faster. You could try a cam assortment to use a more aggressive pump cam. Also think about going up in shooter size.

I have a Barry Grant Stage III 750 on my Camaro that flows 1040 cfm with all the tricks and it is more driveable with better response than the 700 cfm double pumper it replaced.

But the 4 hole would give you more velocity for better throttle response, but it sounds like pump shot to me.

07-01-2016, 08:50 PM	#4
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,740	Re: 4 hole carb spacer for better signal, will it work? Backfire out of the carburetor is a lean mixture issue. Try moving the accelerator pump cam to the number 2 spot so it comes in faster. You could try a cam assortment to use a more aggressive pump cam. Also think about going up in shooter size. I have a Barry Grant Stage III 750 on my Camaro that flows 1040 cfm with all the tricks and it is more driveable with better response than the 700 cfm double pumper it replaced. But the 4 hole would give you more velocity for better throttle response, but it sounds like pump shot to me. __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax