Cliff's Quadrajet Parts and Rebuild Kits
General Category => Quadrajet Carb Talk and Tips => Topic started by: Mr.Pontiac on September 26, 2018, 12:49:20 PM
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This carb. has gotten me steady 11.90,s and comes on like a animal, no hesitation or bog i am running no power piston no primary rods and using 65 jets. Main air bleed in air horn .070 running .135 needle and seat. Pulled idle tubes set them at .038 idle down at .052. Problem is i have no control at both air and fuel mixture screws. Should i open holes behind them to say .080?? or is it something else causing my issues,
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How much vacuum do you have at idle?
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Where is your throttle blade in relation to the transfer slot. With a big cam you may be idling off the main circuit. Is there fuel dripping out of the primary nozzles when idling? To check for proper idle/transfer throttle blade position it requires removing the carb and looking from underneath. If too much transfer slot is exposed you may have to increase bypass air or maybe increase discharge hole diameter as you suggested.
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Removed base plate last nite, Both idle mixture screw holes and Bypass are sitting at .104
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Forgot to mention in last reply, at .050 Duration is 242 on exhaust 236 on intake
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How much initial timing do you have?
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MSD distrib. is fully locked out at 3,000 rpms and timing set at 34 degreee,s
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Is it locked or does it max out at 3000? What's the timing at idle?
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Please forgive me but this has not anything to do with my carb. issues
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If the throttle plates are open too far it does. If you add timing at idle you can close the throttle.
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Sorry it took so long , but i have a little bit of time today to check things out so here go,s, at idle 26 degree,s , with a vacum gauge connected i am fluxuating from 8 to 10 psi very fast.At 32 degree,s
at 3,000 right now i cannot throw any more timing in motor or it cranks very slowly with new battery.This is telling me a ignition problem of some kind i believe, plugs gapped at .032. Motor sounds great past 2,000 if i troump down on it.
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You could open your idle air bypass some but then you'd probably have give some more fuel, idle tubes & DCR.
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Its almost like i am into idle circuit. I tryed to run Cliffs 3 rd reciepe but did not open idle down channels at all. Still factory .052. His book suggests .059 to .064. Plugs where new and all where carboned up after 4 minute running at idle.
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I took off top & opening idle down restrictions from .052 to .062, ill try it tommarrow.
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Appreciate all the help i am getting, Hay, Cliff what do you think??
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If you have zero control with the mixture screws check for nozzle drip.
I'd also put my hand gently over the choke housing and see if it speeds up and smooths out some. If you have either scenario it needs more idle fuel and may also need more idle bypass air.
It would also be nice to know ALL of the engine specs, CID, compression ratio, advertised duration, .050" duration, LSA, etc?......Cliff
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400 cubic inch + .040, compression 10-1, cam specs at .050 Duration 236 on intake and 242 on exhaust. RPM intake, Timing at 3,000 rpm is sitting at 34 degree,s. MSD distib.LSA IS 108 DEGREE,S