Quadrajet Problem Solving > Dialing in your rebuilt Quadrajet carburetor
Idle Circuit Recipie Problems
Shark Racer:
I don't think it could be the T/C. Mine is a stick shift so these maneuvers would be around 1000 RPM at most slipping the clutch - your T/C is likely at *least* 1500 RPM, probably closer to 2000.
When you set the idle mixture did you set it in drive or in neutral?
With an auto, I believe the mixture should be set while the car is in gear. Obviously you'll need a helper and some sturdy chocks for this.
Novarolla05:
I always have the car in drive when I set the mixture. I've never officially heard if that's the right way or not, but it makes sense to do it that way. Makes me feel better to know I'm not the only one doing it that way :)
Something else I thought of. Would running an electric choke conversion help out? Right now I have a hot air choke which as I understand it is basically a vacuum leak. Could I go electric and plug the hole that normally has the small plastic tube in it?
Shark Racer:
I like electric chokes, but I don't think it would help much in this regard. The amount of vacuum "leaking" is very small. If it's hooked up correctly it should be next to none, as the air gets circulated back into the air cleaner (above the secondaries)
TommyK:
What is your initial timing?
How much does the rpm drop when put in gear?
I know everyone says to set the idle screws for best vacuum but I like to set them to where the carb performs the best whatever the vacuum reading may be.
Please bear in mind that I am a Ford guy. I don't know jack about SBC.
Novarolla05:
--- Quote from: TommyK on May 02, 2013, 02:45:54 PM ---What is your initial timing?
How much does the rpm drop when put in gear?
--- End quote ---
Initial timing at 18*, total 38* all in by 3500. My RPMs usually drop 150 to 200 RPM.
--- Quote from: TommyK on May 02, 2013, 02:45:54 PM ---Please bear in mind that I am a Ford guy. I don't know jack about SBC.
--- End quote ---
That's OK, I don't know jack about Fords except my back likes the distributor up front much better than by the firewall ;D.
Here's an update on what's going on. I gave up on the 17059201 quad, but I have another one that I just finished cleaning/rebuilding. I swapped them out, and there was a night a day difference in the low RPMs! Much cleaner throttle response. The new carb is a 17056228, which is off a Chevy 400. Here's the specs.
Idle Tube .036
Idle Channel .050
Lower Idle Bleed .073
Upper Idle Bleed .070
Main Bleed (Horn) .125
Main Bleed (Body) .125
Idle Mixture Holes .089
Idle Air Bypass .055
Float Level .25
Jet/Rod 76/48K APT 3.5 Turns
The only thing I changed on this carb was the idle tube (was .034ish). I have no idea what made the difference between the two carbs idle circuits. The major difference casting wise is the different main air bleed setup, which I would have thought had no impact on the idle circuit. It wouldn't be the first time I was wrong though ;D. I still have some tweaking to do on the primary and secondary side so we'll see what new gremlins pop up. I'm sure I'll have more questions down the road.
Thanks everyone for all the help and great suggestions!!
Richie
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