Fuel or ignition problem

[aermotor]

Car runs "jerky", occasional back fire, top end 45 MPH. Changed dist. body, timed with New Rex, fuel flow through carb. steady stream, points .020, GAV doesn't make much difference. Car had been running good top @ 60 mph, no intake leaks (carb cleaner used). Problem started rather rapidly. What next? 28 Tudor

John

[Gary WA]

what carb are you running?

[Jim Brierley]

Take a compression test and go from there.

[Patrick L.]

If it just started, maybe the vent plate in the fuel cap spun a bit. Try and loosen the fuel cap and see what happens, its quick and easy.

Happened to me. Running fine then suddenly wouldn't go over 45 mph and would belch thru the carburetor showing its displeasure. Of course the first course of action is to over think it and look at other stuff.

[aermotor]

Originally Posted by Gary WA

what carb are you running?

Zenith

John

[aermotor]

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Originally Posted by Patrick L.

If it just started, maybe the vent plate in the fuel cap spun a bit. Try and loosen the fuel cap and see what happens, its quick and easy.

Happened to me. Running fine then suddenly wouldn't go over 45 mph and would belch thru the carburetor showing its displeasure. Of course the first course of action is to over think it and look at other stuff.

Tried that and no help.

John

[Patrick L.]

Hmmm, Ok.

Kinda hard to nail down stuff like this. If you have an in-line ignition tester that would help. It could show if something like condenser or coil is having a problem when warm.
When You say there is a good fuel flow, thats after at least a gallon has been run through the line.?
It sounds like it shouldn't be too hard to find, but, sometimes they turn out to be the hardest.

[Gary WA]

Originally Posted by aermotor

Zenith

John

check all your spark plugs see what they look like

[aermotor]

Number 3 plug had some soot but not really excessive. Others no soot except up in the barrel. Replaced and no change. Haven't received my leak down gauge yet but will go back to timing and carb. cleaning again. Dump MMO in # 3 cylinder?

John

[edzaha]

The GAV not working should be a clue

[Big hammer]

Originally Posted by edzaha

The GAV not working should be a clue

Good catch! I went back and reread, carb needs some work.

[midgetracer]

I just had a similar problem. After changing condenser and problem still existed, I checked the coil and found the tar was leaking around the plastic/ metal joint. Replaced the coil and the problem went away. Old coil had a good spark, but must have shorted intermittently.

[Ernie Vitucci]

Good Morning...since the GAV is not working, you might just have junk in the carburetor and need to take it apart and blow it clean with some compressed air. Take the jets out carefully and make sure you know what gaskets are under each jet, so you can put it back the same way it was...remove everything and clean...also remove the screan filter on the end of the carburetor...check your sedament bowl...Good Luck...Ernie in Arizona

[Rob Doe]

I think the first place I would look, and it's the easiest, would be to pull the drain plug and remove the main, high speed jet from the bottom of the carb. Keep the same number and thickness of washers as the car was running well if it could do 60+. Turn the fuel on and clear out any grit in the bottom of the carb drain area. Catch the fuel so you can see if anything comes out.

See if there is a grain of grit in the jet. If you get lucky, you might not have to remove, or split the carb down.

[aermotor]

Fixed. Not sure how but I blew out all the jets, replaced the float valve, I found 2 jet gaskets bad and the adjusting needle housing for the GAV had the "clip" holding the 4 fingers together still on the housing. Still need to adjust idle speed and idle mixture.

Thanks, John