Was Buick the only GM company to run fuel straight into the Q-jet as apposed to the Chebby that makes a 90 degree bend b4 the fuel filter??? Badly worded but I think I got the point across. Thanks Michael
Early Buick models also had the 90 degree bend. The picture is of a 1967 GS 400. I think the change came with the introduction of the 455 in 69.
Q-Jet '68 GS400 had the straight in fuel inlet. 455 was available in (model year) 1970, maybe some were produced in (calendar year) 1969, Chevy also used the 800 cfm Q-jet later on, maybe through the mid 70's. Later emissions style carbs had very lean calibrations and more and more electronic controls.
pontiac is also straight in, the super duty 455's are the cfm champ coming in at 815-820cfm. cadillac's are 90degree like chevy. q-jet's only came either in 1 3/32 in. primary venturi (750), or 1 7/32 in. primary venturi (850). other ratings are obtained (my guess) by the limiting tang on the seconday top flapper, located on the passengers side, this tang can easily be clipped to give full flapper opening. buick carbs are the best in my opinion, they didn't change much throughout the early '70's and they have less circuits/tubes than the others. good luck
Look down the primary barrels; the 750 cfm has a smaller diameter at the narrowest part. The 800 cfm has a bump at the narrowest part in each venturi right across, diagonally from the "dangerous" screws (the ones in the venturi). You kind of need to see both carbs to understand. No bump = 735 cfm. These are the better carbs for milege and idling. I have 4 800s but use a 735cfm (750) on my 454 pickup. I use 67 primary jets and 49 rods, 3885 ft above sea level in all 450+ cid engines. I seem to get the best milege and snappy performance with this combo using headders.
