Great One Day, Terrible the Next!

[blown240]

Its funny how old trucks can be running great one day and be terrible the next. My 61 Panel has been running great for weeks. Now all at once, its terrible. Wants to stall at an idle, unless its choked. But has to be unchoked to drive at all. Only thing I did different was give it full throttle for a few seconds while driving it the other day. I wanted to see what it has after the motor swap. Of corse the headlights stopped working unless the high beams are on, and that causes the voltage to drop enough where its running off the battery. But at least the alt belt started to squeal, so I know what thats all about. OH, and all of the sudden there is a pretty big exhaust leak.

Looks like some basic maintenance and some ground chasing is in order!

[old cruiser]

If its a 6 cylinder I'll bet you've done a manifold gasket. That will cause the stalling etc by pulling in air and makin it run too lean , also it's probably where your exhaust leak is. Standard prob on gm inlines.

[blown240]

No, it's a 350 with a qjet. I'm sure it just needs to adjusted. Probably running lean like you suggested.

[TJ's Chevy]

Quadrajet = Quadrajunk. Heck my truck is 48 years old...never had any issues for 2 years straight...and I ain't hardly done anything to it. lol 6 bangers rule. lol Yeah I know...has nothing to do with that. Oh yeah..the point to my post....sounds like a little water or bad gas is in the carb...might do good to clean her out a bit.

[chevyrestoguy]

Fix your electrical issue first. Depending on what ignition you're running, a low voltage condition can cause issues that will act exactly like a carburetor problem. Check out the squealing belt first and verify the output of the alternator is at 13 volts or higher. Your issue may still be a carburetor issue. The fact that you went full throttle for a few seconds may have caused a blown diaphragm or gasket, a stuck float, or you might have some trash in the needle and seat.

Q-jets can be a great carburetor when they work right. They are a complicated piece, and not everybody has the patience to work out their little bugs. When you've got one that'll open the secondaries without bogging, it's a beautiful thing. They give decent mileage if you stay out of the secondaries, but if you're a gearhead, that's almost impossible to resist.

[blown240]

It has a HEI. The voltage is only low with the lights on, but the carb issue is constant. Once I have some time I'll look into it.

[Hansome]

Have you checked the timing on the dizzy,
Had a similar issue with my truck fine one day then not wanting to start the next or the next.
Though it was carb issue and suspected rebuild or bushing causing vacuum leak...... But it turned out to be the hold down clap on HEI dizzy was slack and after several days driving it had managed to slip out of timing.
Re set the timing with strobe and now there are no issues . Admittedly I had check everything else systematically first and was losing my rag when it stumbled across my mind I should just check the timing as I hadn't since I purchased the truck. It seems that it would account for why the truck had been not quite running right.
It might not be your problem at all but you never know.
Best of luck

H

[blown240]

Thanks. Timing is about 11 degrees advanced with the vac advance unhooked.