Quadrajet Problem Solving > Dialing in your rebuilt Quadrajet carburetor

Edelbrock Performer RPM 1910 idle tuning for more cam.

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avmechanic:
Turns out the bypass air holes were .055" so I opened them up to .110" that helped a bunch I could close up the butterflies a fair bit but they need to go more. I only have 9.5 to 10" of vacuum. My plan is to add some more initial timing and reduce the mechanical some more on my MSD distributor. I have the Black 18 degree bushing in there so I can't reduce it more with what I have. I ordered a kit with a 14 degree and 10 degree bushing so will try one of those and bump the initial up. I did it temporarily and could get it idling nicely with more like 14" of vacuum but would have too much total timing if I left it that way. If I still need more bypass air after adding some timing I will drill the bypass holes out a hair more.

Kenth:
With 10" of vacuum i would open the idle tubes to at least .040", the downchannels to .062" and idle needle holes to .095"-.099".
If you have vacuum in the ported source for distributor vacuum advance after this mod you may need some added bypass air.

HTH

Cliff Ruggles:
Not all 1910's have the same idle calibration.

I've observed at least four different calibrations on virgin/unmolested units sent here over the years. 

In any and all cases record all the items related to idle fuel delivery before making any changes.

IFR's, DCR's, upper and lower IAB's, bypass air and the size of the holes under the idle mixture screws.

I've had at least two 1910's in here without any idle bypass air at all, and several with .038" IFR's and others with .040" IFR's, for example. 

Upper and lower IAB's have been consistent and most have had .055 DCR's as Kenth mentioned........

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