I have a problem on 2 Q-Jets. One has been reworked with bigger jets, idle bleeds or basically I following the "receipe" from the Cliff Ruggles book.

First the reworked one. At idle it drips from both boosters. Float level is set to spec. I have screwed with the idle screws till you are blue in the face. I have idled down to 550 so the plates are virtually closed. The carb is adjusted so vacuum is at 17-18" Still drips which is rich as hell and smokes when you jab it.

The other Q-Jet is a rebuilt unit from National Carbs that bolts right on oout of the box. Idles great, but drips from only one of the boosters - not both. Again adjustments and checks.

Both carbs will idle well and the engine pulls about 17" of vacuum.

Now - I put on a Holley street avenger with an adaptor block and guess what - no drip from the boosters. Granted this is whole different technology etc but no drip and no serious rich smell. Wife can't stand me in the house when I come in.

What ideas do you have for the Q-Jets as that is my goal to run one as they run well and have great throttle response, but not if they are dripping. There is a common issue here that I am failing to see. I doubt both carbs should drip as that says to me the fuel is being pulled out of the boosters. The fuel pump is a stock unit so I don't think I too much pressure. No gauge to tell actual pressure.
Thanks for any ideas or educating me on this mess.
Jim

 

I would guess that either your float level or fuel pressure is too high. Your fuel pump may not be operating as advertised, but you won't know unless you get a fuel pressure gauge on it. If it's too high, a fuel pressure regulator should work some magic for you.

 

Ruggles is an expert, but I think his approach is probably not best for your average rebuilder. Once you start pulling and modifying idle tubes and bleeds, you had better know what you are doing or you can end up with a real mess. Nozzle drip is a common problem with incorrect idle circuit setup.

I doubt the stock pump is producing too much pressure.

Put a thin screwdriver down the float bowl vent hole and be sure the power piston goes up and down freely.

Double check the float level.

Be sure you hooked the float on the arm correctly (not hooked through the hole).

Did you use a new (and correct) nitrophyl float? You could have a fuel logged float, or an incorrect float.

Be sure the float arms are not bent so that they bind against the power piston tower.

Did you modify/ replace the power piston spring? Too stiff a spring can cause your problem.

Check the primary rods and hanger are not damaged (bent). Especially on the carb that is just dripping on one side.

Did you follow the proper air horn screw assembly order and not over torque them? You can warp the air horn and cause the problem you describe.

There are a lot of very similar gaskets in a Q-jet rebuild kit. If you use one that does not have the idle bypass air passages, again, it can cause nozzle drip.

You may also end up needing to adjust your idle bypass air.

Hope this helps.

God bless, Sensei

 

Many thanks Sensei, could not have asked for more info and "to do " list of items. Jim