750 to 800 Baseplate swap

[BadBrad]

I have a fine running 1970 Buick 455 quadrajet and a "parts" 1972 Buick 455 qjet. Is it possible to swap the '72 baseplate onto the '70 carburetor to take advantage of the larger primary opening on the '72 carb?

[omaha]

I'm sure, barring some passage misalignment issues {big ?}, that it could be swapped over. I dont think it would be a good Idea though. Unlike holley carbs. the q-jet used different base plate butterfly sizes for their two CFM ratings of 750 or 800 {roughly}. ( the rare '73 pontiac carbs not included) These butterfly sizes matched their specific main body application. (holley used 2 different sizes also BUT had various cfm ratings for each size butterfly's). With the Q-jet, this would have to be accomodated by porting of the main body for a smooth transition from one to the other.  It is possible that interferience problems could occur.  the real problem is that the airflow advantage was gained from enlarging the main body venturi, (not the baseplate). swapping over to the larger baseplate would not have much effect in my opinion. Upseting the low speed fuel curve may also be another problem.  Just my .02

[Cliff Ruggles]

It is always best to stick with the original part.  For Buick carburetors, there were several different baseplate used in the early 1970's.  Even though they may physically fit, there are differences in them that would effect how well they work and which gasket is needed.....Cliff