low idle air bleeds leaking

[rrossi]

What would be the cause of the low idle air bleeds in the main body to be spraying fuel in the venturi?

[Frank400]

in what condition are they "spraying" ?  I'm asking because at one point they act as air bleeds, and at other times, they act as fuel discharge.

[rrossi]

at idle. 850 rpm. 1967 Cadillac 429, stock rebuilt engine by someone else, rebuilt carb by who knows who. replaced with rebuilt from summit.  mixture adjusts ok, but when HOT, car restarts poorly, have to rev for 3 secs to stabilize.  Idle gets rough after 15 minutes. Look down the carb and low idle bleeds are spraying like crazy. "above the throttle plate, below the boosters"  Throttle plate angle is good.

I believe after warm-up the heat is causing something to dump excess fuel and then the idle deteriorates unless off-ilde periodically to 'clear'.

[Frank400]

I'm no expert but I'd check if you have the correct gasket and stainless plate set-up between carb and intake, I believe those are like Pontiac and Chevy of the same years, very important. 

     Also, from what I've seen and a lot of guys here, "commercially rebuilt" carbs are the worse you can get, as most of the times they have cancelled idle air bypass. 

  When you say the throttle blade angle is correct, can you elaborate ?  For those bleeds to be spraying, the throttle somehow has to be opened quite a bit.  I'd try to close it completely and giving the engine it's needed air by unplugging a vacuum hose and seeing what happens.  If that solves the problem, you now know you need less angle and more (some at least) idle air bypass.

   Frank.

[Cliff Ruggles]

Rebuild from Summit?

Those are among the very worst I've seen, and I don't want any more of them sent here for any reason.

Leaking into the intake after shut down AND fuel going into the engine at idle may indicate miss-matched parts or no upper idle airbleeds to break the siphon effect. 

Upper airbleeds are REQUIRED and if missing or blocked the entire fuel bowl will siphon into the engine as soon as the engine is shut down......Cliff

[rrossi]

Good answer. I went back and redid the mechanicals. compression test (210) leak down test less than 25%.  vacuum gauge fluctuates very rapidly 1/2 " at idle 825 rpm @ 17". Cold, higher idle 20"
Well, I have 2 junk carbs and I'm not sure what to look for when its apart. I already purchased and installed the correct carb plate & gasket). I have had the tops off both carbs. 2 different plunger styles. One of the carbs definitely had the secondary air bleed plugged. Plugs are rich. The rebuilder is gone & ditched the original carb. What to do?

[Cliff Ruggles]

It's no big secret that I am not a big fan of anything commercially "remanufactured" and if you Google hard enough you will see my comments on various Forums about them.

The quality control these days is absolutely PATHETIC, and they use low quality internals and the wrong internals.

For these reasons I will usually recommend to obtain a "virgin" original unit and build your own vs throwing your money away with "reman's".

Unfortunately a 1967 original Caddy carb is NOT going to be an easy core to find, but the good news is that a later unit thru at least 1970 would be just as good if not better........Cliff