In a message dated 10/16/2008 12:54:39 P.M. Eastern Daylight Time, ronbo97@xxxxxxxxxxx writes:
Hi Joe -
Glenn Barratt said you'd be the right person to consult for my carb issues.
Maybe, maybe not. I worked exclusively on Chryslers, so have no direct answers regarding Stromberg carbs. I thought they only used them on trucks! I can try to help, though.
At Chryslers at Carlisle this summer, I bought a nicely rebuilt 2 bbl Stromberg 15-28 carb to replace the Stromberg 15-28 that was (so I thought) giving me problems on my 58 Plymouth with a 318. The car runs well now with the exception of the following issues:
1. When making a turn and stepping on the gas at the same time, the car feels like it's going to stall. I have to feather the gas pedal to keep that from happening.
Does this happen when you are turning both ways, or only left or right? The only difference when turning would be in the fuel level "sloshing" one way or another. Is the float level set correctly, and is the top of the carb fastened firmly to the bowl? Is there a vacuum port that goes through the seam between the carb body and the top, like up to the choke? Some of the WCFB carbs had a problem when turning left with the throttle closed. Fuel would slosh up against the seam and get sucked into the engine, making it stall, which stopped the power steering in the middle of a turn. Several cars were wrecked, and we were quick to fix that! We put a little brass tube into the body casting to bridge the seam.
2. When adjusting the mixture, if I lean out the car to where it's idling at around 500 rpm when in gear, it runs somewhat rough. If I shut off the car for a few minutes, then try to restart, it takes a while to restart instead of restarting right away. I've also had a couple of stalling problems at this rpm. However, if the slow idle is brought up to around 625, these problems mostly disappear.
Two problems here, maybe. As to the hard start after shutting off: If the engine is warm/hot when shut off, I think it is probably the fuel boiling over into the manifold from latent heat. This might be helped by putting an insulated (Bakelite) spacer between the carb and the manifold, If you can find one. This is made worse by the modern fuels, I hear. Mine ('59 Saratoga) does it. I just live with it, by holding the throttle wide open when starting warm, to clear out old fuel. I also just remembered that a loose carburetor top could provide a path for fuel to go into the carb throat and thus to the manifold, too. Be sure that your float and needle assembly are sealing off incoming fuel completely. If the needle valve leaks, this can cause flooding, in various degrees at low engine speeds.
As to The rough idle, this can be caused by so many things! Vacuum leaks, bad valves (burnt or out-of-adjustment), ignition, etc. I think I'd start by pulling the carb and looking at the throttle plates and throttle shaft. An old shaft can be worn and sloppy in the bore, causing an erratic leak and poor idle. I would also back off the idle speed screw and be sure that both throttle plates seat firmly in the throttle bores. It is very easy and quite common to set the carb down on the bench with the blades sticking out and bump them out of alignment. If they don't close properly and fully, you need to (gently!) loosen the screws and reseat the plates. When seated, they may want to stick slightly in the bore, but when you set the idle speed up they should be OK. From fully closed, open the throttle plates 1 1/2 turns for a basic setting.
Remove each idle mixture screw and check the tapers. They are brass, and frequently have damage from someone tightening them up too tight. If the taper is damaged, it makes them hard to adjust. Sometimes they can be refinished by spinning them in a drill press (Vertical lathe!) and using a fine mill file to reshape them.
Put them back with the springs, close them gently to seat them, and back them out 1 1/2 turns.
Reinstall the carb. The basic settings should be good to get the engine running and warm it up. To set the mixture, adjust the throttle speed screw until it is running around 500-600 rpm. Open both mixture screws together (1/4 turn on 1 side, then 1/4 turn on the other side) until the speed stops increasing, or falters. (This tells you that you have enough fuel to run the engine.) Then turn them in closed again, 1/4 turn at a time, together. The engine should continue to run smoothly until it begins to falter from lack of fuel. This is a critical time. Pay full attention to the engine, and if you have a vacuum gauge, use it. The moment that the engine begins to falter, or the vacuum drops, stop closing the screws and open them up about 1/8 to 1/4 turn. This should give you a firm, steady idle. You may need to reset the idle speed and even may want to reset the mixture screws to get it just right.
If, when you are at this stage of the game you notice that your vacuum gauge is giving a regular, repeating "Bounce", you have been blessed with a bad valve and need further help.....
Good Luck, and let us know what you find!
Joe Savard
Lake Orion, Michigan
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