Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem
Flat spot/bog in 1st gear, after shifting gears
2Low8s:
Appreciate it. I'll turn the pressure up to 7psi and do some measuring/checking in the next couple weeks and report back. Been studying (reading over and over) the parts of your book related to idle and modifying idle circuit. I really appreciate the book, and your guidance here!
2Low8s:
Per your advice and the book, I increased fuel pressure to 7psi, changed to the 73 jets, and set the carb up for 'recipe #2'. Car runs GREAT, but still fighting idle.
My idle tubes were .040, and I 'resized' them down to .037 for the time being with a drill bit and needlenose pliers, rolling the idle tube around the drill bit shank end and kneading the 'jet' side with the pliers. IDCR was just a tad larger than stock, and resized it to .052.
I measured the amount of exposed transfer slot which was under .040, maybe closer to .035. During a test drive we moved the vac advance back to ported, and now it will run ported for the first time without having a bunch of the transfer slots exposed/fully.
I still have no control over the mixture screws- once past 1/2 a turn out the exhaust smells rich. When I fully seat them, the rpm starts to increase and I pick up vacuum. Does that mean I need more bypass air, or should I resize/order smaller idle tubes (and IDCR?), and add bypass air if that doesn't yield mixture screw control?
1/2 turn out- vacuum fluctuates between 12-14"
fully seated- vacuum fairly solid 15".
77cruiser:
What sizes are your idle air bleeds? Solder the tubes shut & redrill.
Cliff Ruggles:
How big are the holes under the mixture screws? Remove the springs from the mixture screws and verify that you are able to shut off any fuel from the mixture screw holes.
Make sure you don't have any nozzle drip.
How much transfer slot is currently exposed at idle?
2Low8s:
77cruiser- Idle air bleeds are .070. Solder as in soldering for electric connections?
Cliff- I'll pull the screws and measure, as well as see if it shuts off fuel sans springs. I'll double check for nozzle drip, but did not see any prior to this point.
I have somewhere between .035 and .040 transfer slot exposed at idle.
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