67 Quad won't act right, what am I overlooking - Chevelle Tech
Troubleshooting Diagnosing problems done here.

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post #1 of 11 (permalink) Old Mar 3rd, 19, 11:23 AM Thread Starter
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67 Quad won't act right, what am I overlooking

Guys, my original 67 Q jet is dumping or pulling fuel thru the normal fuel spray centers at idle . It appears to me as fuel level is too high. I have pulled and checked several times the float setting. The setting called for is 9/32 and I have even moved it to 12/32 to see if thats my problem. The carb has worked perfect for many years and only after I let it sit up for many years did the float get struck open. Just popped the top and got it unstuck....but the thing just ran rich from too much fuel.....even after shut off the engine would run for a short bit. Pulled it and did a complete fresh rebuild and its doing the same thing. The only thing I noticed the last time apart was the little clip that holds the inlet needle on the float itself had a bigger gap than the old needle /seat assembly. The new needle and seat appeared to be same length and size as older unit. I am over looking something. I feel I should readjust the float even more lower.....even though I am lower than correct set point of 9/32.....any ideas..
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post #2 of 11 (permalink) Old Mar 3rd, 19, 11:48 AM
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Re: 67 Quad won't act right, what am I overlooking

Plastic foam floats can get waterlogged. Best replace it if there is any doubt. Don't sweat it, they're cheap.
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post #3 of 11 (permalink) Old Mar 3rd, 19, 1:29 PM
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Re: 67 Quad won't act right, what am I overlooking

Have you recently change the fuel pump? Some have too much pressure.
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post #4 of 11 (permalink) Old Mar 3rd, 19, 6:30 PM Thread Starter
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Re: 67 Quad won't act right, what am I overlooking

I do have an extra new float....but just felt that is not the culprit. I have pulled this one apart minutes after shutting off the motor and no signs of a leaky float. Fuel pump has been there for years but I just replaced the fuel tank and pick up / sending unit. All that is new stuff. It s funny you say that as I put on another Q jet i had that has been sitting around for who know how many years and fired it up.....seems it was dumping in extra fuel also.....just chalked it up to needing a rebuild. thanks....
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post #5 of 11 (permalink) Old Mar 4th, 19, 4:46 AM
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Re: 67 Quad won't act right, what am I overlooking

Have you checked the alum plugs in the base of the carb body for leakage? They were a problem especially on early carbs.
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post #6 of 11 (permalink) Old Mar 4th, 19, 5:49 AM Thread Starter
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Re: 67 Quad won't act right, what am I overlooking

Yes, I had put a dab of epoxy on them a while back and it is still holding good. I have several cars and I seem to let sit way too long and as the carb dries out the floats become gummy stuck open. And so that usually means at least pulling the tops off to unstuck. My 69 Chevelle does not ever have that problem. I suspect that those plugs leak and the fuel leaks out and the float never sticks.....waa laah, fires up every time..lol....
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post #7 of 11 (permalink) Old Mar 4th, 19, 8:03 AM
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Re: 67 Quad won't act right, what am I overlooking

Does yours have that vent that allows you to check the float in operation?

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post #8 of 11 (permalink) Old Yesterday, 11:00 AM Thread Starter
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Re: 67 Quad won't act right, what am I overlooking

Hey Guys, trying to resurrect an this old thread as I am trying again to get this original carb back in working order. Basically , the fuel is coming out the main discharge nozzle when the engine is a idle. As you can guess it is way over rich and will run on after engine is shut off. It began doing this ONLY after I went in to clean out some crud after it sat for a long, long time. I just ASSUMED fuel drizzling out the discharge nozzle could only be caused by a too high float level and that is where I have been looking. But now after setting the float level quite a bit below correct level and still having this problem, I am not sure what else can cause this condition. Any ideas what can cause this other than float level.....thanks.....
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post #9 of 11 (permalink) Old Yesterday, 11:25 AM
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Re: 67 Quad won't act right, what am I overlooking

Are we to ASSume you put a new float in there and are still having a problem?

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post #10 of 11 (permalink) Old Yesterday, 12:18 PM
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Re: 67 Quad won't act right, what am I overlooking

Is the power valve free and working? Can you push down the power valve with a pencil through the vent with the engine off. Is it pulled down when the engine fires? Can I assume since the float stuck you had a good amount of shellac in the bowl and if so did you soak it. I find WD40 works great cleaning a carburetor. Does the accelerator pump function correctly? I suspect you either have a stuck power valve or low engine vacuum and not pulling the valve down. Certainly worth checking the fuel pressure. Never assume anything. First fact two carbs run rich spilling fuel and only the fuel pump would cause that.
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post #11 of 11 (permalink) Old Yesterday, 10:38 PM Thread Starter
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Re: 67 Quad won't act right, what am I overlooking

Yes, new OEM float, three new sets of needle valve and seat. Power valve is loose and works as always has. I don t think I can check the spring action with a pencil on this model card but will take another look. The fuel pump is the same one and has been working fine for many years.....but I am not sure of its pressure. I did a clean up and mini check on another old quad. I had laying around and it fired up seemed to run ok. Did not take the time to dial it in since the throttle and choke setup is much different than the 67. Thought maybe I am just overlooking something simple but they both looked and were assembled the same. I have one on a 396 that works perfect....I may pull it and see how it does on the 327, that should show for sure its the carb and not engine or fuel pump. Thanks for the help guys, we will figure it out as I am sure it was something I done......
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