Quadrajet Problem Solving > Dialing in your rebuilt Quadrajet carburetor

Rebuilt 7041204 issues

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ernie3:
Thanks in advance for any help. I have a 7041204 that was rebuilt by a reputable builder (not Cliff) that I cannot get completely tuned. This is going on a ’71 vette, AT, 454, automatic with a mild, unknown cam. The big issue is I cannot get the secondary’s correct, I’ve adjusted the air doors as per the book. It doesn’t have the kick that it had and for a couple of minutes after WOT it acts like it’s flooded, it does not want to stay running. It also has developed hard starting after sitting a little while, after stopping for lunch it does not want to start, it acts like it’s flooded and takes a minute or two to get back to normal – just like after WOT.

Until I go WOT it’s a pleasure to drive, it runs a little cooler, throttle response is good and no problems smoking the BF Goodrich’s with a little power braking. Prior to this carb it had a q-jet from a ’77 truck, it was running great until the float started falling apart then I started the journey of chasing the correct carb and trying to get it set up correctly.

The carb started out as a commercially re-manufactured, butchered carb with a host of issues. Here’s what I know from the build sheet:

71 jets
42B rods
.047 MAB’s
9/32” float
CV secondary rods
Idle air bleeds .066 upper, .075 lower
Idle tube .036
Down channel restriction .060
Idle bypass .096
Idle screw .089
Adjustable APT in baseplate
Secondary rod hanger height .640

I have it set up with 16 degrees initial timing, centrifugal is all in by 2500, total timing at 36, adjustable advance limited to 52 degrees. Vacuum advance is ported, total vacuum at idle is 13” and the idle is little choppy but holds steady at 675, drops 50 rpm in gear.

I also have a barely noticeable off-idle flat spot and only at light throttle, I should be able to get that right with tweaking the APT a tad more.

I purchased and have been studying Cliff’s book but am struggling with tying my symptoms to any particular fix. I’m not sure what direction I need to go. WOT issues related to the hard starting? Primary side causing the secondary issues? Any guidance is much appreciated.

Ernie

429bbf:
welcome to chp. ernie this might be a stretch but i think the bottom plugs are leaking . ill explain . when you shut it off the gas is running into the engine and flooding it . when you go to wot they leak so bad that the gas is going straight into the intake instead of up and over and being metered correctly. might sound stupid but its worth looking into. I'm sure someone else has a better answer. fwiw

ernie3:
Thanks for responding 429bbf, they were epoxied and plugged when it was rebuilt.

Ernie

tayto:
i know cliff refuses to rebuild commercial "remanufactured"  units now unless they are needed for restorations. hopefully you wont need another core to rebuild.

Ethan1:

--- Quote from: ernie3 on June 15, 2016, 09:04:16 AM ---Thanks for responding 429bbf, they were epoxied and plugged when it was rebuilt.

Ernie

--- End quote ---

 BUT, what type of epoxy was used? If JB-Weld, it could still leak after multiple heat cycles and gas erosion. If Marine-Tex, good chance it is a permanent repair.

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