Does this sound lean?

[Marx3]

Hi, my buddy has a 68 Corvette with a H.P. 327, all stock. He bought a brand new Qjet from some company that sells Corvette-stuff only. I am not sure about the quality.
Problem is that it rattle at medium/heavy/WOT throttle... Total timing is 32, so that should not be the problem. I thought maybe it was lean, so I took the carb apart to measure everything...
SO! does this sound lean for an old 327...

prim. jets     .068
rods             .033
idle tubes     .038
down ch.      .052
lower air bl.  .060
upper air bl.  .090

Sec. rods        CH/.055
POE well restr.     .030
POE restr.            .040
tube restr.           .023
M hanger

Some of the measurements are appr. or very close, as I did not have all the drillbit-sizes.

[Cliff Ruggles]

There are no "brand new" quadrajets that I know of, it would probably be a commercially "remanufactured" unit.

You list two airbleed sizes, are those idle or the main airbleeds?

If those are idle airbleed sizes, what are the main airbleed sizes?

What is the carburetor part number?....Cliff

[Marx3]

sorry for the delay, been busy during the weekend.

I guess I was a little fast, when typing the numbers the first time, here's the second try :-)

the lower idle air bleeds:  .062
the upper idle air bleeds: .090

main air bleeds in airhorn: .052
main air bleeds in body:     .114

carb number is 7043208

You are propably right that it is a remanufactured model of some sort. The body just looks different than other "original" Qjets I have ever seen. And the baseplate don't look like an "original" either. It looks kind of cheap, you know :-) But I am no expert!

[Cliff Ruggles]

Those main airbleeds sizes are not "stock" for that model, it's been recalibrated.    The .033" rods are also a miss-match for those jets.  Probably a "generic" calibration they came up with.

Has the APT system been disabled?.....Cliff

[Marx3]

The APT has never been there... No hole for it in the body, no APT at all.

[Cliff Ruggles]

The APT system on that carburetor was in the baseplate, between the idle mixture screws.  The power piston should have a steel post on the bottom of it to engage the APT.

In almost all cases the entire system is removed when those carburetors are commercially "remanufactured".

Getting back to the original question, it would be quite lean for the application at heavy/WOT, based on teh specifications provided......Cliff

[Marx3]

There are no wigns of that type APT either...

But, okay, so if I re-set everything to recipe 1, than the vette should be good to go right?

[Cliff Ruggles]

If the APT system is completely missing, then it's a commercially remanufactured unit, and probably a bunch off miss-matched parts with a generic calibration.

I hate to see those coming, as they are the most labor intensive to repair.  I'd take it back to the factory configuration close to what a 1969 SBC q-jet used.  .050" main airbleeds at both locations, .068" main jet, rod about 30 numbers smaller, "B" series, AX, CE or DA secondary rods,  idle system from recipe in our book to match the engine combination.....Cliff

[Marx3]

I really think the baseplate looks like it is newly made, you know, the casting ust looks a little different from an old baseplate.
The body has holes for bypass air, should I go through the process and drill the baseplate etc? Or is it not necesary for a close to stock vacuum-level?

I will email you about rods etc I might need, when I get to rebuilding it.

Thanks alot!!!

[Cliff Ruggles]

In any and all cases, the carburetors calibration/fuel curve must be matched exactly for the application, if you want the best results in all areas.

This seldom comes from anything purchased commercially remanufactured/rebuilt (good news for us here!), so fully expect to have to do some tuning in one or more areas to get it up to par.....Cliff

[Marx3]

I will simply enjoy modifying it! I thank you very much for the specs!

And to think that those carburetors cost around 300$ on summit... come on!
:-)

[Cliff Ruggles]

I get a LOT of those carbs sent here, and HATE to see them coming.  Quality is poor to pathetic.  I can't believe that a company who dedicates themselves to supplying "high performance" parts sells them....Cliff

[Marx3]

hehe, that's what I thought.

He was told that it was "calibrated to match his original 327 setup exactly" Bahh!