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Old 10-30-2017, 06:55 PM
earntaz earntaz is offline
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Quote:
Originally Posted by VintageMusclecar View Post
Braved the chill this morning and pulled the QJet off for the needed tweaks.

-Restricted idle air bypass circuit. Note: most "rebuilders" block this circuit off completely with lead plugs, which causes an excessively rich idle and transition circuit. Most stock engines run fine with this circuit as-delivered, but I find restricting the circuit instead of blocking it off provides better results.

-Swapped choke pull-off for one I modified for a replaceable restrictor to fine tune secondary air door opening rate

-Swapped primary jets from 74 to 72 (stock is 71) (49 PMR-stock)

~1/2 dozen test drives playing with pull-off restrictor sizes and secondary air door tension, have about 90% of the bog out.

The carb now idles perfectly with the choke on, and I can drop it in gear and drive it w/o it trying to stall out now. Idle only drops ~150 rpm where it was dropping 250+ before.

The car is so much crisper and more responsive with this carb on it it's not funny--and I had the Holley pretty well dialed in. I think I'm going to build a later model unit (no aneroid) to test with next. QJets are without a doubt a serious bitch to dial in compared to a Holley, but man they run so damn nice when you get them dialed in.

More later.
I love it when I hear folks calling these carbs a "Quadra-junk" -- GM stuck a ton of money in development of the QJ. In the right hands it works damn good. If I remember right Ford used a version of it and Chyrsler Corp also. TAZ ...
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