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My 1937 120 is equipped with its original Stromberg EE-14. When I purchased the car, the carburetor appeared to have never been touched. It leaked out of the float bowl, and the throttle valve shaft was sloppy, so I had it fully rebuilt, to include replating all surfaces and rebushing the throttle shaft. The vendor (Chris's Carb Shop in Dayton, OH, which was recommended by Daytona Carb) flow-tested it prior to shipping it back.

The carb mostly works great - I set the idle with a vacuum gauge, verified the choke was properly adjusted, etc. I've also given the car most of a full tuneup (haven't gotten around to adjusting the valves yet)

My problem: the car runs extremely rich. Cloud of black smoke wherever I go, and soot dribbling out of the tail pipe. I suspect the power jet may be leaking by.

Here's what I know:

1. The car doesn't use any oil.
2. Timing is good.
3. It starts immediately, even after sitting for a week or two.
4. Power is good.
5. The car does get a little warm on hot days at idle or pulling a hill, but I suspect that's cooling system related, not carb related, and isn't the point of this post. Just trying to include all information.

I'm tired of the smoke cloud. Any tips on troubleshooting the carb to determine the source of my problem? I'm hoping to solve it myself so that I can continue to drive the car.

I've looked at my section of the Stromberg manual on this site, and couldn't see anything on repairing or troubleshooting the power jet.

I'd rather not throw it away and put on a Carter since it's already rebuilt, etc. but thta's the final plan if I can't get it to run cleanly.

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Stuck or leaking float would come to my mind as first suspects. Is the carburetor being fed by the standard mechanical fuel pump?

Yes, standard fuel pump, nothing extra.

I had kind of ruled out a leaking float because the float bowl is always full, even if the car has sat for a month, it fires right up. Before I had it rebuilt, the float bowl emptied when it sat, and you had to crank for 15-20 seconds before it would catch.

How would I check for that condition?

Edit: I was thinking float bowl, not leaking float. Big difference. Either way, the float is neither stuck nor leaking.

Make darn sure the manifold heat riser flap is open. if closed, or partially closed, will cause...umm...problems. You've probably checked this, so revert to carb diagnostics.

You comin' to Hershey?
DAF

I checked that out when I rebuilt it some time back, but maybe I'll wire it shut, just to eliminate it while I'm troubleshooting.

On Hershey, likely no. Still working a few things, but I think the Navy is going to keep me from going.

Fuel bowl draining on those units is caused by clogged air bleeds in the main jets. The rebuilder obviously cleaned those and fixed that problem.

The car will run with the top taken off the carburetor.

You can check the float function that way.

I've had sticking accelerator pumps cause overloading power valves when they don't return.

You can remove the valve and inspect it, if it is leaking the car should be loading at idle as well.

Tim, thanks. I'll give that a shot! The car runs rich from idle to redline.

What on inspection would indicate leakage? Perhaps I can put something through the port and look for leakage?

Pulled the top of the carb off to inspect float function. Interesting how it does run, very well, with the float cover off, although a bit of a fire hazard!

The float seems to operate smoothly, as does the accelerator pump. The book (Stromberg Manual) on this site calls for a fuel level of 15/32" below the top surface. Since my car was running rich, I thought the float would be too high, but it appears to be correct, or maybe even a little low. I did observe that the float moves freely, and does not appear to sink or leak. All of that checks with having it professionally rebuilt a few years ago.

I verified the float doesn't leak by dunking it in hot water and adjusted the level slightly.

I confirmed the main jets are the proper size. Edit: see picture.

I confirmed the power inlet check valve is functioning properly.

I put a little carb cleaner in the accelerator pump passage to test that the pump inlet check valve and power bypass jet were functioning correctly. (Pieces 28 and 29 of the Stromberg manual respectively). As expected, no fluid moved. When I removed piece 28, the check valve, the passage drained immediately. The jet seemed to move smoothly, but I thought it should be shut until 65-70mph and a near wide open throttle position. I'm pretty convinced this is my problem - where do I find a new one?

Wouldn't you know that the blasted heat riser valve isn't dropping properly? I'll wire it EDIT: open (weight down) and see if that changes anything.

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If I understand the operation and reason for the heat riser valve why would you wire the valve closed VS open?

Agreed. You sure you didn't have a typo because weight down should be open and if you are going to wire it anywhere, open it should be or overheating and burned valves are a real possibility.