Dear Board, I have a 74' Buick 455 that my brother has just rebuilt. I have a mild TA cam, stock 8.5-1 pistons, and stock heads with a mild port job. I have a Edelbrock intake with a Holley 750 vac secondaries. It has a TH400 tranny and 373 rear end gears. My question is, and I have imagined it has been asked a million times, what Q-jet should I use? I have seen all of the decoding lists for Q-jets, but they do not state the size of the carb. I do not care about originality, just as long as it is a straight gas line feed carb (Buick set up), with a rating 800 + cfm. It looks like the board favors the 850cfm Q-jet, and if someone could give me an idea what these carbs came equiped on, I could go from there. I am looking for a mild performance carb with plans on upgrading power in the future. Thanks.
Scottie, IMHO your best bet is a 800 CFM Q-jet. Look for the following #'s, these are all Buick 455 800 carbs. It is important to use a big block carb on a 455. All the 455 carbs from 71-74 were 800's. The 350 carbs were 750 CFM and had smaller idle passages and calibration. 7041242, 7041243, 7041540, 7042240, 7042242, 7042243, 7042942, 7043240, 7043242, 7043243, 7044141, 7044240, 7044242. Hope that helps, Happy hunting:TU:
Thanks for the reply. I imagine that is a popular question around here. Those numbers help alot. Is there any other GM sister brand that would make a good substitute? I imagine that these carbs might be hard to find. I'm just trying to keep all of my options available. Thanks Larry70GS.:grin:
Scottie, Those carbs are not that hard to find, with the exception of the Stage1 #'s. Oldsmobile also had the front gas inlet. I don't have the part #'s for the 800 carbs. The only difference is on the primary side. Both carbs use 1 3/8" primary throttle blades. The primary side has triple venturis. The outermost venturi is formed by the carburetor casting. For the 750's the outer venturi measures 1 3/32", on the 800's it measures 1 7/32" or an 1/8" difference. If you do a search on 800 Q-jets, someone posted a picture of the primary side of the 800, and how to ID them. There is a little bump in the casting where the outer venturi clears some internal passage. If you do a search, you should be able to find it.
Thanks for the help. I'll be looking for that particular post soon. I like the idea of the Q-jet better than other carbs, as I have a driver. Rarely will I be taking it to the track, the car is just a 60 foot street terror. I am leaning toward the q-jet over the holley 850 because of the price(almost $500 for a 850 holley vac sec.) and ease or mantainence (Holley requires constant tuning). I also do not want an edelbrock, have no experience with them, they also seem cheap. Thier price seems level with a rebuild q-jet though. I hear q-jets are untouchable when they are working properly. Have any feedback on edelbrocks? Just curious. Thanks for the help. Scottie
GM sister's I think you should be able to find a Buick carb. You may run into linkage problems with a non buick carb. If I remember right, I think the olds uses different choke set-up. I just always goes nice when you start with the right parts.
