Stalling on acceleration help needed

[rhm63]

I have search the boards and tried several things but I still cant figure it out.
This truck was my daily driver in the mid 90's and it ran well, then it was parked outside(covered) until a few months ago. This is my first time working on any vehicle, I am learning as I go.

It is a 63 stepside 230 ci. Everything is stock or oem except for the new blazer tank from Brother's that I installed in the bed.

So here is what is going on. It is running rich and already fouled one set of plugs. It idles rough periodically. It is not constantly rough but once it warms up it stumbles every 20-30 seconds (rough estimate). And it stalls on acceleration. It doesnt cut off if I let off the gas or if cycle the gas pedal. It makes a whooshing sound from the air coming in the carb, and to my untrained brain it seems like there is too much air coming in, so it stalls. If I gradually press on the gas it will go to higher RPMs. I have driven it around the neighborhood and if I accelerate it seems like it is missing (could be plugs are fouled again). And if it does stall or I cut it off, it takes a few tries to get it cranked again.

Here is what I have done: New distributor and points, new manifold/exhaust gasket, vacuum advance works, new plugs, valve adjustment. New rebuilt carb, it is a Rochester re-manufactured by Holley.

The only two things I can think of is the timing or something in the carb. Maybe both. I just wanted some opinions before I go buy a timing light or tear into the carb.

Thanks

[Dans66Chevy]

I would say 100% carb problem. Sounds like you have a couple problems with it. I would pick-up a kit and some carb cleaner. Take it apart and let it soak a day or so.Get the cleaner in the gallon can with the basket. Should be about $25 for the cleaner and $25 for the kit. Put it back together and I think it will solve your problem.

[RANDY COX]

Could be a serious Vacuum leak...

[dfrank]

The off idle stumble seems to me like the accelerator pump circut needs some tuning as does the whole carb. Clean it real good and just keep tinkering with it. It is hard for me to diagnose exactly what it is over the internet. Just start with a good cleaning and make sure you idle mixture screws are set right. The best way to do that is with a vacuum gauge and adjust the mixture screws till you get the highest vacuum reading.

[66Submarine]

Sounds like the accelerator pump is weak, and the idle mixture is extremely rich (loading up with fuel and wanting to die when warmed up). Did you mess with the distributor and not set the timing afterwards? You need a timing light; setting it by ear at idle is great, but only if all your driving is at a no-load idle.

I like the run the idle mixture screw in until it runs rough and back it out until it just smooths back up. This needs to be done when the engine is warmed up to operating temp (obviously).

This is what my plugs look like (and what yours should look like).

[rhm63]

Thanks for the tips. I havent done anything to the timing and the distributor doesnt have any play in it. Hopefully, it is good.

I kind of suspected a carb issue. I already have a kit for it. When I took the old one apart i found a crack and got the rebuilt one. I think I made the mixture too rich trying to adjust it so that it did not stall when accelerating.

I will give it a go and update. And I probably pick up a vacuum gauge.

And for curiosity sake, where could there be a major vacuum leak? I have manual brakes and steering. The vacuum advance on the distributor seems to work, I can see it moving under load. I have had a hard time getting my mind around the vacuum system. I know how vacuum works, but not quite how the whole system works together.

Thanks again.

[Dans66Chevy]

I own a couple Ice Cream Trucks. They both came with the 292. Im not much of a fan of the 292 but thats a hole other story. The intake/Exhaust manifolds get warped and the next thing you know you have a leak. I could spray starting fluid around the manifolds and the idle would pick right up. For whatever reason those manifolds suck. Had them surfaced a couple times and a month later same exact problem. I found a fix to my problem. I put 350 Chevys in both of them. Both run perfect now....

[TJ's Chevy]

Carb done gone bad. Bolt on a new one and yer troubles no doubt will be over.

[Mackie]

Now that you say you tried to compensate for the bog by richening the idle screws I think your problem is in the accelerator circuit or poor fuel delivery. If you can coaks it to high RPMs and it maintains it there we can rule out fuel delivery. Working the throttle while you look down into the carb throat (engine off) you should see the accelerator nozzles squirting.
But first you have to make sure that your timing is correct, valve adjustment done and there's no vacuum leaks. Carb adjustment is the last stop on the tuning road.

[oem4me]

Like Mackie says, look down the throat of the carb with a flashlight while working the throttle. Every pump should produce a healthy stream of gas. If you do not see a stream, the accelerator pump in the carb is bad or its outlet is plugged.
I had similar symptoms and the bulk of my trouble was solved when I discovered the plugged outlet right in the carb throat. I had frustratingly removed and cleaned the carb like four times, each time overlooking that one passage. A single poke with a bent wire ended up fixing the problem, and that one I did with the carb in place.

[dfrank]

What carb is this? If it is a holley I would check to make sure the accelerator pump linkage is adjusted properly. You want it to squirt as soon as the throttle moves and you also need to have .015" clearence between accelerator pump linkage and accelrator pump arm at WOT or you can stretch and damage the pump diaprham. As for finding the vacuum leak. Take I mini propane bottle and run it around the carb to find a leak. The engine rpms will go up when you find a leak.

[66Submarine]

Originally Posted by dfrank

What carb is this? If it is a holley I would check to make sure the accelerator pump linkage is adjusted properly. You want it to squirt as soon as the throttle moves and you also need to have .015" clearence between accelerator pump linkage and accelrator pump arm at WOT or you can stretch and damage the pump diaprham. As for finding the vacuum leak. Take I mini propane bottle and run it around the carb to find a leak. The engine rpms will go up when you find a leak.

Holley-branded reman Rochester Monojet or model B.

As everyone else has said, it sounds like you have a weak/non-existent accelerator pump shot, and you've tried to cover that by enriching the idle until it won't idle anymore. You should see a strong squirt of fuel when you look down the carb and work the throttle.

[dfrank]

Originally Posted by 66Submarine

Holley-branded reman Rochester Monojet or model B.

As everyone else has said, it sounds like you have a weak/non-existent accelerator pump shot, and you've tried to cover that by enriching the idle until it won't idle anymore. You should see a strong squirt of fuel when you look down the carb and work the throttle.

Stupid me. I now remember reading that the first time I read the thread.

[Jimal]

Originally Posted by rhm63

I have search the boards and tried several things but I still cant figure it out.
This truck was my daily driver in the mid 90's and it ran well, then it was parked outside(covered) until a few months ago. This is my first time working on any vehicle, I am learning as I go.

It is a 63 stepside 230 ci. Everything is stock or oem except for the new blazer tank from Brother's that I installed in the bed.

So here is what is going on. It is running rich and already fouled one set of plugs. It idles rough periodically. It is not constantly rough but once it warms up it stumbles every 20-30 seconds (rough estimate). And it stalls on acceleration. It doesnt cut off if I let off the gas or if cycle the gas pedal. It makes a whooshing sound from the air coming in the carb, and to my untrained brain it seems like there is too much air coming in, so it stalls. If I gradually press on the gas it will go to higher RPMs. I have driven it around the neighborhood and if I accelerate it seems like it is missing (could be plugs are fouled again). And if it does stall or I cut it off, it takes a few tries to get it cranked again.

Here is what I have done: New distributor and points, new manifold/exhaust gasket, vacuum advance works, new plugs, valve adjustment. New rebuilt carb, it is a Rochester re-manufactured by Holley.

The only two things I can think of is the timing or something in the carb. Maybe both. I just wanted some opinions before I go buy a timing light or tear into the carb.

Thanks

The rich/fouled plugs combined with the stalling under acceleration makes me think that either the float in your carb is bad or some dirt got into the needle and seat and the carb is overflowing. I had it happen to an 80's Dodge I once owned. In that case, there was a problem with the charcoal canister that allowed the charcoal granules to backwash to the carburetor and screw things up.

[rhm63]

Its a Rochester B. I did not see a squirt of fuel looking down the carb. I am thinking maybe some dirt got in the line when I switched to the bed mounted gas tank.

I did spray some carb cleaner around the manifolds and did not get a response from the engine.

I will pull it off and see tomorrow. Thanks again for all the input.

Just in case you are wondering this is what she looks like.

[dfrank]

Originally Posted by rhm63

Its a Rochester B. I did not see a squirt of fuel looking down the carb. I am thinking maybe some dirt got in the line when I switched to the bed mounted gas tank.

I did spray some carb cleaner around the manifolds and did not get a response from the engine.

I will pull it off and see tomorrow. Thanks again for all the input.

Just in case you are wondering this is what she looks like.

I think the truck out grew trailer. Lol