SmokinBBC
Well-known member
I need an education on the subject.
I was dreaming on what I might do if I ever wanted to swap my carb out. So searching the web for different ideas, I ran across this carb from jet performance. In the description you can see the recommended engine specs including a compression ratio of 8.5 to 9.5-1(assuming the mean static). My qjet BB is within all the other specs, but has a 10.5.1 static CR running 93octane at 34 mechanical advance without any problems.
I don't recall seeing CR listed in any other specs for carbs except on the JET site.......so what's the the link between CR and the carb usage?
"JET Performance now offers a Quadrajet carburetor tuned for Chevy & GMC cars and trucks with 396 ci and larger modified big block engines. The carburetor is extensively reworked by increasing main well size and is balanced to assure top end high RPM fuel flow. Several circuit modifications are made to keep the fuel curve correct throughout the entire RPM range and to keep consistent idle quality. Includes a .149 needle and seat to ensure adequate fuel flow. The carburetor is designed for modified big block motors with a dual plane intake manifold, headers, 8.5-9.5:1 compression ratio and mild ported or aftermarket heads. Recommended cam specs: Duration @ .050 min 210 degrees, max 240 degrees and a lobe separation angle of 110-114 degrees. "
I was dreaming on what I might do if I ever wanted to swap my carb out. So searching the web for different ideas, I ran across this carb from jet performance. In the description you can see the recommended engine specs including a compression ratio of 8.5 to 9.5-1(assuming the mean static). My qjet BB is within all the other specs, but has a 10.5.1 static CR running 93octane at 34 mechanical advance without any problems.
I don't recall seeing CR listed in any other specs for carbs except on the JET site.......so what's the the link between CR and the carb usage?
"JET Performance now offers a Quadrajet carburetor tuned for Chevy & GMC cars and trucks with 396 ci and larger modified big block engines. The carburetor is extensively reworked by increasing main well size and is balanced to assure top end high RPM fuel flow. Several circuit modifications are made to keep the fuel curve correct throughout the entire RPM range and to keep consistent idle quality. Includes a .149 needle and seat to ensure adequate fuel flow. The carburetor is designed for modified big block motors with a dual plane intake manifold, headers, 8.5-9.5:1 compression ratio and mild ported or aftermarket heads. Recommended cam specs: Duration @ .050 min 210 degrees, max 240 degrees and a lobe separation angle of 110-114 degrees. "
