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Repairing stripped Idle Mixture screw hole in throttle body

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Cliff Ruggles:
Easy fix, take them up to 10-32 threads on both sides and use the pre-1979 style mixture screws.....Cliff

Ethan1:

--- Quote from: Cliff Ruggles on August 07, 2015, 04:46:22 AM ---Easy fix, take them up to 10-32 threads on both sides and use the pre-1979 style mixture screws.....Cliff

--- End quote ---

 I would go with Cliffs recommendation. 8)

Reaper19:
Thank you Ethan and Cliff. I was able to talk to the local carb rebuilder that did my carb and he agreed this is something they should have caught in their rebuild, so they replaced the baseplate. Problem now after installing the new base plate the throttle shaft has a lot of play in/out as well as side-to-side causing the idle to jump around, TPS  voltage to jump around and not stable. Looks like the baseplate was not re-bushed at all. Also after testing on the car, the carb is now leaking fuel through the throttle shaft onto the intake, so it must also be flooding. So to say I am not satisfied is beyond description. I have taken this carb back 10 times to this place and every time the original issue is not repaired, worse or another issue arises. So I am taking this carb back one more time on Monday and give them one more chance to get it right, otherwise I will ask for a refund and send it out.

Cliff, these are my specs. Hopefully my engine builder did not steer me wrong and I can still get the E4ME running with the build. Would you be able to rebuild the E4ME to run with this setup?

1981 Corvette Specifications
Carburetor – Model 17081228 with Black M/C solenoid and electric choke

Motor: Chevrolet 350
-   Bored over 0.30
-   Pistons EngineTech P15334 Flat Top
-   Cam EngineTech ES1014R – These are the numbers that are close. The builder did not provide exact specs and these were pulled from the internet for the Cam with make and model that was installed
o   Stage 1
o   Hydraulic flat followers
o   0.50 Duration
   204 Dur. Int.
   214 Dur. Exh.
o   Cam Lift .280/.295
o   Lob center
   C/L Int 107
   C/L Exh 117
-   Heads - Chevy 333882
-    Intake – Original factory Aluminum 14033058
-   Exhaust – Original factory design 2-1-2 with Magnaflow High Flow Catalytic Converter
-   Transmission TH350C
-   Rear Differential gear ratio 2.87

If you can, what is the turn around time or approximate cost? If you rather discuss on the phone I can contact you during the week.

Thanks Randy

Cliff Ruggles:
Good news on the cam choice, it's the standard Melling/Speed Pro "RV" cam for the small block Chevy.  Very good cam for 350cid engines around 9 to 1 compression or so.  It will make PLENTY of vacuum at idle and low speeds to keep the computer happy.

If they can't get the carb working correctly, call the shop and we can discuss options, time frame, etc.....tks...Cliff

Reaper19:
Thank you Cliff for confirming the new parts installed during the engine rebuild will work properly with the CCC!  :D i have kept telling the carburetor re-builder something is wrong with the carb and the engine re-builder new what he was doing having a drag racing background and building tons of these engines over the last 25 years. But now after returning it 12 times to the carb re-builder and each time having it come back with a different issue I have finally told him that was it, I was finding someone that can help get the car running properly.

The carb is the correct original model for the year and engine for the car, it just needs to be properly gone through and set up correctly. After fighting this thing since the beginning of March 2015, I read more on rebuilding and adjusting than ever. I have some of the tools required for adjusting and rebuilding, and borrowed others from a mechanic friend, the only one I do not have is the gauge for setting up the lean screw. But probably can try to find one online or create a gauge for the proper height adjustment. I may, with your suggestions try to rebuild the carb again from scratch myself, unless you feel it would be best to send it in. 

I also wanted to mention I have gone through checking all sensors, switches, wiring, looked for vacuum leaks, changed out all vacuum lines, vapor canister, TPS, M/C, EGR, CAT, thermal switches, replaced all ignition items, except HEI coil, removed the air pump and have an OTC Monitor 85 to check all systems. All are checking out good with no codes. THe car runs great at WOT and cruising, the only issue is the engine will not idle correctly, bounces up/down, rough, not steady or smooth. Also, when adjusting the idle mixture screws they have no affect on the RPM's at all. So there is definitely something going on with the carb.

I called the shop and left my number, look forward to hearing from you.

Randy

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