The Stovebolt Site Forums The Shop Area Engine Shop 216ci with Carter W-1 stalling when warm

I recently bought a 49 Chevy 3100 that the previous owner said has a 1952 216ci engine with a Carter W-1 carb. I've never owned an old vehicle like this, so I'm still getting familiar with it. The truck starts with little need for choke, and idles great when cold. When I drive it, it runs great except for when I slow down to stop, in which case the truck stalls. I can keep it from stalling by keeping the idle up using both feet. When it does die, it starts easiest if I hold the gas pedal to the floor. It doesn't seem to idle as smoothly when warm either. My thought is it's flooding, but would appreciate other thoughts on the potential problem.

It certainly sounds like it's flooding. I would pick up a carb rebuild kit from your local auto parts store along with some Berryman's Chemtool (or whatever your preferred cleaning spray is) and give the carb a quick rebuild.

Is it possible that the choke cable is not set right so that even though the choke nob is in all the way, the carb is still choked? That would account for the easy start and good idle when cold. It would also make it run bad when warm.

Just a thaught.

Make sure to get the correct carb kit, a '49 W-1 is all by itself.

I do a lot of Carters and have lots of original parts and pieces but for that particular one Jon (carb king)would be your best bet, get all the right numbers off the carb - carters are very precise about thier carbs.
The hardest thing is to get them apart, easy to rebuild after that.
If you get in a 'spot' post up a pic or two of where you are and theres' several of us on here that can give you first hand expert advice, ok?

It is certainly possible that the carb is the issue HOWEVER there are other possibilities that should be covered first:

(1) The first diagnostic test on even a rebuilt engine is a compression test. If the engine has a burned or sticking valve NOTHING else one does will matter.

(2) The symptoms posted are a classic symptom of a pertronix conversion instead of points. In fact, even though 50 years of training says compression test first, I would be tempted to pull the cap and look to see if a pertronix was present. (Actually, if it were my vehicle, I wouldn't have to check, as I would KNOW there was no pertronix in my distributor!).

(3) If good compression, and no pertronix, then the third item would be testing the spark when the engine is hot. Old coils can go non-linear in the secondary side, which kills the voltage. A perfect carburetor and low plug voltage will run rich.

(4) If one through three pass muster, look at the fuel delivery system. Electric fuel pumps are great for eliminating vapor lock, and filling an empty carburetor for easy starting. Virtually all of them produce MORE pressure than the carburetor likes. With the proper fuel valve installed, the W-1 will handle maybe 4 1/2 psi maximum. With too large a valve from a generic kit, maybe 3 psi. And the $29.95 dial-type regulators sold in the FLAPS are useful only if you have a strong right (or left) arm, and a rabbit issue in your garden!

(5) If compression, ignition, and fuel delivery all pass muster, then it is time to look at the carburetor. If you truly have a 1949 carburetor, I would suggest patience and locating a 1948 carburetor at a swap meet or on-line. Parts for the 1949 carburetor, while available, are contructed from verypricium! As mentioned above by both Don and OJ, the 1949 is a year by itself, and the accelerator pump is unique. Since there is virtually no demand for a unique pump, the pump must be custom-made. We do this, but VERY time-consuming, thus costly.

Jon.

Thanks guys for all the suggestions. I'll obviously start with the easiest checks first and make sure it isn't something simple, like the choke adjustment. The guy I bought the truck from said the engine was rebuilt 10k miles ago and has good compression. He recently did a tuneup with new plugs/points, and rebuilt the carb, but I don't know anything about the coil. Since the engine isn't a '49, I'm assuming the carb may not be either, so I'll have to validate the model year if I do isolate the carb as the problem.

Theres a saying 'most carb problems are in the ignition' and are truer than you think.

'49 was the last year for the W-1. Starting in '50 they started using the Rochester B. If you post a picture we may be able to help you identify things better. Does your carb have a tag on it?

Diagnosis of engine problems is kind of like shooting pool. You should try to make the easy shots first. Rebuilding the carb is definitely not the easiest shot.

There's no tag on my carb. I put some pictures in the linked folder below which will hopefully be adequate to identify it.

Truck pictures

I guess I suffer from familiarity complex. I've rebuilt so many carbs in my lifetime that it seems like second nature, and it's something I would do even if I didn't think the car was acting up or the cause of the problem. Especially the older one barrels and two barrels I find extremely easy to do.

I guess it's not that easy for some folks.

It is a 1949, and while you can certainly try, you are NOT going to find a rebuilding kit at the local parts store.

And Greg, no offense meant to anyone, you or the gentleman from whom you purchased the truck. It takes only a few minutes to do a compression test. Then you know. If you have just one sticking value, NOTHING that you do to anything else is going to fix the problem.

Don't take someone's word for anything....test it.

Every single used car I have bought in the last 52 years had a "rebuilt engine within the last nnnn miles", even the ones that hadn't run in 20 years (just rebuild before we parked it)!

My checklist should be done in order, as the later items will not fix defective items earlier in the list.

Jon.

I finally had some time today to fiddle with the truck and tried a few things.

First off, responding to some of the previous comments:
Compression - There's 85-90lbs in all cylinders
Ignition - Good old points inside the cap. 6V coil looks fairly new. Plugs, points, and wires recently replaced.
Fuel - Good old mechanical pump. Inline filter
Choke - The choke plate is opening fully when off

As I said originally, the truck generally runs great out on the road, so I'm really thinking this is a carb issue. One of the things I tried was to put my hand partially over the air horn. The engine speed goes up and it idled smoother if I blocked the airflow just right. To my thinking, this implied I wasn't getting enough fuel, and the air/fuel ratio was too lean. I adjusted the idle adjustment screw further out, well past the 1-3/4 +1/2 turns and the truck seems to run better. I was able to drive it without it dying when I came to a stop, but it still doesn't seem "dialed in". The service manual says "If it is necessary to turn adjusting screw more than 1/2 turn in either direction to get a satisfactory idle, internal trouble is indicated." One thing I noticed. I don't see any sign of a gasket between the carb body and air horn. If it's there, it's paper thin.

Any further thoughts from the experts out there?

Sounds like a vacuum leak. In the majority of cases, holding your hand over a carbs intake and the speed picks up suggests it's sucking air between the carb and the intake valve(s). Adjusting the fuel air generally doesn't eliminate it because theres generally not enough fuel/air mixture available to offset a big volume of air entering via vacuum leak "after" the idle fuel/air mixture port.

The carb could be have a vacuum leak itself, the carb to manifold junction, the manifold and/or manifold to head junction.

Theres several ways to test/discount this, but it definitely sounds like a vacuum leak.
Good luck
Dave

After seeing the results of your compression test, and knowing no pertronix and a recent electrical tune-up; I would look at two items:

(1) As Dave mentioned, a vacuum leak
(2) Coil

The fact that is runs well on the road would tend to mask the effects of a vacuum leak (the air leaked would be insignificant at cruise RPM, but could become significant at idle).

A defective coil can still produce sufficient voltage at cruise, but insufficient voltage at idle. Coils, if bad, will have worse symptoms as the coil warms, as the secondary impedance will become non-linear.

Holding one's ones hand over the airhorn (personally, I would use the choke butterfly) could improve a defective idle caused by either of the above causes.

Jon.