The Q-Jet I'm working on has a divorced choke setup. It also has a plastic diaphram that mounts near the choke mechanism that has a rod that connects to the air valve. When the vacuum is high the diaphram is closed and pulls the rod this then does not allow the air valve to open. Under low vac, wide open throttle, the diaphram opens and allows the air valve to open the secondary system. My problem is my carb is missing the diaphram and according to the books I have they are calibrated with the orifice to the specific combo you have. Its a 350 sbc stock early 70's and the original diphram had a single straight lever with a hole in it. When I give the parts guy the Q-Jet # he brings out a diaphram that has a bunch of other tangs on it besides the single lever. Can anyone here help me figure out which diaphragm I need?

Are you going to Chev. or a parts house. The generic parts house models won't work correctly unless you are real lucky. I haven't checked in a while but Chev used to sell them.

Todd what parts house are you useing? I have had good luck with NAPA. Are you talking about the choke pull off(Vac Break Diaphragm). Some pull offs have an arm that goes to the primary (choke) as well as the secondary air valve and when the choke warms up the linkeage allows the secondary air valve to open.

------------------
67 BB Prostreet Camaro COMBAT RAT
71 BB Chevelle (SS clone)
80 Camaro Z28 355 SBC
2002 35th anniv. SS Z28

If you go to a Napa store or an Auto Value you can get Blue Streak carb parts. Any of those places have the choke pull-off that you need. The simple choke pull off that Chevy used is still available. They used the same part on Zillions of carbs.

Mike

if you still are having trouble getting the right part, give Cliff Ruggles a try. He specialises in working on quadrajets and should have the part you need.
http://tbns.net/qjetcarbs/



------------------
1968 Pontaic Firebird, 462cid, TH400.
I know its not a Chevelle, but it is still fast.