Fuel System: New rebuilt 289 2BLL still runs like crap after professional carb rebuild

[jostanton1]

I had the stromberg 2 barrel rebuilt on my 289 GT Hawk. And the engine still runs rough, some misfire and can't idle to 550 rpm. Timing and points set. Plugs show carbon, so it's running rich for sure. I noticed gas dripping at the throttle shaft on the drivers side. Could the floats be messed up? I paid $200 for the rebuild from the only carburetor rebuild shop in Vegas. Now I'm having my doubts that he knew what he was doing.

[PackardV8]

A carb shop could hardly be given an easier task than a Stromberg WW.

Start with the basics. Which fuel pump is on the car? Which air filter? Which fuel filter?

jack vines

[TWChamp]

I agree with Jack.
Also, you can open the valve on a propane torch, and without lighting it, move it around the intake manifold to check for leaks.

[jclary]

Gee...even rebuilt carburetors in Vegas is a gamble?

There's a fellow SDC member I consider a friend. I see him at least once a year at the Tri-State meet in North Carolina. About ten years ago, I bought a rebuilt carburetor from him. The next year he asked how I liked the carburetor. I told him it worked great after I rebuilt it!
It has been our running joke now for years.

Seriously though, it seems that "rebuild" has an unclear meaning to various rebuilders. And to answer your initial question, the float could be not adjusted properly. I've seen rebuilt carburetors with a new needle valve, but a worn unchanged valve seat. New accelerator pump and nothing else, but called "rebuilt." Float replaced, but not adjusted. On some of these carburetors, you can flip a gasket the wrong way and it will not perform because there's a circuit covered up by placing the gasket incorrectly. (I don't know if yours is one of those)

Carburetor toolkits have various gauge wires for clearing jets & fuel passages, but often us "backyard" rebuilders overlook or never understand their use. If you open up a so-called rebuilt carburetor and still see sediment in the bottom of the fuel reservoir, that is usually a sign that the rebuilder never went any further than replacing the obvious wear parts like needle valve, seat, accelerator pump, gaskets, and sometimes, the float. Even if rebuilt perfectly, the installer will be responsible for getting it back on with no vacuum leaks and making the fine tuning final adjustments. Have you gone back to the shop you paid your hard earned cash and asked if they could make it right?

[bensherb]

I had the stromberg 2 barrel rebuilt on my 289 GT Hawk. And the engine still runs rough, some misfire and can't idle to 550 rpm. Timing and points set. Plugs show carbon, so it's running rich for sure. I noticed gas dripping at the throttle shaft on the drivers side. Could the floats be messed up? I paid $200 for the rebuild from the only carburetor rebuild shop in Vegas. Now I'm having my doubts that he knew what he was doing.

I had one that did the same thing after a carb rebuild. I lowered the float level to fix it. It ended up well below the spec I had, but didn't affect it's opperation any.

[Mike Van Veghten]

When was the last time the valves were adjusted ? Could very well be the cause of the rough running.
As far as jetting, all the rebuilder can do is verify the "original" jetting is in place and set the float height and drop. Can't bad mouth him for the jetting. Also, if the fuel pump is putting out too much pressure, this will cause an over rich condition. And yes, a stock pump "can" do this. BUT, you didn't mention that detail..!
A tiny (almost invisible) spec of dirt can cause a needle and seat leak, causing a rich condition.

Mike

[53k]

I had the stromberg 2 barrel rebuilt on my 289 GT Hawk. And the engine still runs rough, some misfire and can't idle to 550 rpm. Timing and points set. Plugs show carbon, so it's running rich for sure. I noticed gas dripping at the throttle shaft on the drivers side. Could the floats be messed up? I paid $200 for the rebuild from the only carburetor rebuild shop in Vegas. Now I'm having my doubts that he knew what he was doing.

Before I gave up and bought an Edelbrock I took a Carter AFB to a local man who has old cars, works on Studebakers, etc. He ordered the proper AFB parts and the carburetor was absolutely beautiful even to making a new carburetor tag when I picked it up. However, when I installed it and tried to adjust the carburetor, there was no way to make it run right. I had even told him that the throttle shaft needed rebushing. Guess what wasn't done.

[altair]

To start with you should be assure that everything is in spec, the intake manifold should be resurfaced to assure no leaks as with the exhaust manifolds. Carb to manifold gaskets clean and tight (but not over tight), check fuel pump pressure. Make sure there is no debris at the needle and seat rubber tipped needle is better, confirm the float height. Jetting should not make any difference as far as idling and running rich, there isn't that much difference between the smallest and the largest. An issue with the idle jets would only be a lean condition as they don't get any bigger they just get restricted.
About the only way a rich mixture can occur is float too high, a leaking needle and seat or choke not fully open. Excessive fuel pump pressure would be uncommon.

[StudeRich]

My FIRST guess would be worn Centrifugal Weights in the Prestolite Distributor (if correctly equipped, and if it's a '62-'64).

Number TWO possibility is: since they obviously did not re-bush the Throttle Shaft holes in the Aluminum Carb. Base, that will be a problem.

[studegary]

It may be something as simple as the car having an electric fuel pump installed with too much pressure.

[jostanton1]

Exactly what I thought. I've rebuilt dozens of the things. I have the standard mechanical fuel pump. Standard inline fuel filter and stock air cleaner.

A carb shop could hardly be given an easier task than a Stromberg WW.

Start with the basics. Which fuel pump is on the car? Which air filter? Which fuel filter?

jack vines

[jostanton1]

I'm taking it back today. Thank-you.

[kxet]

Last kits I bought have not had gaskets to go under small screw in pieces such as jets and plugs, this was for Stude 1 barrel and Mopar 1 barrel. Anyone else have the problem.

[tim333]

Send it to Dave Thibeault, it’ll come back looking and performing better than new.

[RadioRoy]

The few times I installed a "professionally rebuilt" carburetor for someone, I ended up rebuilding it again myself. And this was on a 53 Champion car. How much simpler could it be?