Hot Rods Car starts then blubbers

Here's the situation my Model A starts great runs for about 45 seconds then starts to sound like its running on 4 cyls. 283 with rebuilt 500 cfm Edelbrock rebuilt by a reputable shop, had them look at it twice.New pertronix distributor and flame thrower coil. New plugs and wires. Put a fuel regulator on it, adjusted it from 3 to 5.5 pounds.Checked the fuel filter not plugged. I've driven it about 25 miles before this, it had a bad flat spot off idle, had the carb shop look at the carb, they said everything looked good. After I put it back the engine would hardly run, put the regulator on and it ran good for 45 or so seconds then run like shit.Any ideas? This car has been a curse.

 

Maybe starts flooding after a few seconds?
Carburetor needle valve being overcome?
Choke not staying open?
Very first thing for safety... check for fuel in the crankcase.

 

I believe if it was ignition, it would run crappy all the time.

 

I would think with the regulator set as low as 3 lbs it would not flood. Manual choke.

 

Are the plugs wet or drier than a popcorn fart?

 

They look dry. I'm not letting it run long after it starts to run shitty.

 

Sounds like it might be a defective float in the carb to me.

When it starts running crappy, have you looked down into the throttle bores to see if there was gas dripping in to them?

 

If I let it sit for a little while and start it, it runs good for 45 seconds or so then the same shit all over again.

 

It sounds like fuel to me too, I second gene.

 

Check the accelerator pump shaft. Its plastic,and should be straight. If it has taken a curve thats your problem.I went throught it with the same carb. It would start,but not idle long.If I keep the rpm way up it would run.I noticed the curve,and pushed it straight,and the idle settled down.

 

Tell us about the choke...is it manual? electric? or other?

 

Found it! Thanks Gene fired it up ran good looked down the carb till it started to run crappy, the one side quits flowing gas. Crap in the carb?

 

You're gonna think I'm a damn idiot, but have you tried choking the fuck out of it? I've been running those carburetors for quite some time, and they are picky as hell about what comes through them. Get you a big rag, start it up, crank it up to about 2000-3000 rpm, and while you hold it there, smother it with the rag, cover the entire top. Some people call it burping it. It'll clear it out good. They run like shit with the smallest of crud in them. Also, if anybody pulled the top off of the carb to check the bowls, and gambled on the metering rods lining back up with the main jets, it could have a bent metering rod

 

That why I look for carter AFBs at swap meets.

 

Dirt in the carb. Of course.
I've done what Lloyd said... sometimes you can suck the debris through the jets. Usually gotta at least drain the bowl and blow it out with carb cleaner and compressed air. Sometimes gotta pull the bowl and clean it, though.
Good luck. It's going to run a lot better. No more curse. LOL

 

Got 'er runnin' smooth yet?

 

Loosen the flapper covers on the metering rods. Turn them out of the way & see if the bad rod plunger jumps up w/ the other w/ the engine off. Like Lloyd said, it could be bent and stuck in the jet. I ran across that one a couple years ago.

Joe

 

I must admit I've never heard of flooding a carb out from 2,000 -3,000 rpm to clean crud out of float bowl, I can see where it might help with a plugged passage inside the carb though.

At any rate, if the issue is crud in the float bowl, I'd replace the fuel filter, just because it shouldn't let crud get into the carb.

I guess we are mostly assuming you have a good air filter protecting the carb, but maybe we should be asking that as well?

 

Have you tried removing the air cleaner and shining a flashlight down the venturis while it's idling to see if there's too much fuel running into the carb?

 

Now wait just a minute guys, we all know carbs are simple..............

I'd put an O2 sensor in the exhaust.......even a temporary use one and see what it tells you when the engine isn't running right. Gotta know whether you are rich or lean. Great for tuning the carb too.
Friend of mine crashed his newly restored airplane on its maiden flight because the professionally rebuilt carb had a hole in the float. Engine ran fine during numerous taxi checks, ran fine on take off, and started acting up only after he took off. He managed to walk away but the plane was destroyed. Point is that it ran fine initially, then the float filled with fuel and didn't float any more.

 

Pull a couple spark plugs and see if they're black and fuzzy or otherwise. If it is running quite rich, it'll foul the plugs in short order. You said you didn't run it for very long while burbling, and you said it still runs good for a few seconds before it starts doing that, so you probably didn't foul the plugs, or at least not too bad. But after your fuel issue is resolved, be sure to clean or replace the spark plugs as needed.

 

Bought a new carb, problem solved. The shop that I bought this rebuilt carb from was trying to blame ignition and my wiring for the problem, I got tired of arguing with them so I sent it back for a refund. Should have done that to begin with.Just have to do a little adjusting and cruise.

 

I put new plugs in. And I'm going to change the oil.

 

Two fuel filters. Replaced them both. New air filter.

 

Yay. Happy cruising...