New Rebuild - Couple of Issues...

[leeklm]

Hello,

Armed with Cliff's book and HP kit, just finished my first qjet build, but have two primary issues...

1. Cannot get idle speed below 1,200 rpm
2. Falls on its face at 4K in 2nd gear (float?)

Carb #7043252 on a stock low compression 400 with headers/dual exh. 4spd.

Pretty much "stock" qjet rebuild, with mods including:

--Installed larger air bleeds that came with my kit
--Notched the secondary air horn plates by the bleed holes
--Enlarged secondary air/vent tubes to .038
--Installed new primary shaft bushings.
--Check other passages, etc, as instructed in book

I bought this $10 carb as a rebuilder, so never had it running prior.  When driving, seems to run smooth, good off-idle (1,200 rpm idle) transition, no stumbles, etc.  When "going through the gears", motor runs good to 5K, but then seems to run out of gas at 4K in 2nd gear.  I assume this is a float issue??  Runs fine again as soon as i back out of throttle.  Thought I had float set at 1/4", but need to check again.

I disconnected choke and fast idle circuit to ensure there is no interference, plates seem to be closed, but still cannot get the engine below 1,200, even when manually applying pressure on the throttle linkage.  Vacuum at 1,200 rpm idle is 18.  When putting my hand over air horn, engine seems to act as it should... quick gain of 100rpm or so, then immediately stumbles and wants to die.

Not sure if it is impacting the condition, but the primary plates do have the idle holes drilled from the factory.

Any thoughts in this would be greatly appreciated.

One last question… My HP kit came with a thick purple base to manifold gasket (with the bushings in the bolt holes) and another black gasket (about ½ the thickness).  I assume the purple gasket should be used?  What is the purpose of the black gasket?

Thanks!!

[leeklm]

After a little more investigation- it looks like the linkage connecting the primary and secondary  shafts may have been a little tweaked, holding the secondary plates open ever so slightly.  I tweaked the rod back in order to give the secondary a little more room.  Too late to fire up the car, but I have a feeling this will fix my high idle problem...

[Cliff Ruggles]

Common problem.  The secondary throttle plates should be tightly shut at idle, and there must be some clearance between the link and the arm or they will get held open slightly....Cliff

[leeklm]

Thanks Cliff.  Regarding running out of fuel at 4K rpm, the measurement to top of base near end of float was within 1/32 or less of the factory spec of .25".  I tweaked it up to just over .25 and will see if it impacts the condition.

I also have a 7042264 qjet (by Carter) that runs pretty decent on the car, and will run up to 5k, so assume my fuel supply is good.

BTW, any thoughts on the black & purple base gasket question?

[Cliff Ruggles]

We supply a 1/4" thick gasket in addition to the stock gasket.  If the choke system still works with the thicker gasket, I'd use it......Cliff