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Carburator shaft air leakage

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1950 Plymouth, P19, has all new engine parts, no miles since rebuild. Rebuilt the carburator. Had it apart many times. Had several helpers. Starts good, sounds good, valves almost quiet. Vacuum advance works well. Engine bogs and will only rev up when you nurse the throttle. Thought it was stuck mechanical advance but a friend thought it was gas. He smeared axle grease on each end of the carburator throttle shaft and it ran great. Oh, then the grease melted off. So as it happens when you remove the throttle return spring you can make the carburator shaft move all around. Buddy Jesse Harvey drops off a box of carburators but only one for a 230. It's a little loose too. In a few days i'll exchange the bases on the two carburators and see what I have then. But I plan on adding another carburator so I'll need two good ones. And finally my question is: Who's got over-sized shafts and bushings? Who does the machine work if the shafts have to be built up and turned down? Many thanks for you all's help as this site has been invaluable to me for the past 18 months. 

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Agreed, worn throttle shaft = vacuum leak = poor performance. The fix is usually to remove the butterfly & shaft, and bore the casting to match a tight fitting larger standard size OD  bushing that has the correct ID for the shaft. I dont think the shafts wear as much as the casting, but that would be a guess on my part..

If you want to try fixing it yourself, I imagine you need to be darn sure you bore the casting square and straight. Probably best to have a competent machine shop do this. You could try contacting some specialty carb shops to see if they can help, Holley rebuilds any make carb. Try talking with George Asche as well. He rebuilds lots of these carbs.

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I feel like an idiot but I've looked at the resources section half a dozen times. I can read all about George Ashe but I can't find a phone number or address. Can someone help this poor old redneck by guiding me to this info. Thanks, Carl

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10 minutes ago, jhm1mc13 said:

Pronounced  Ah - she.

Thanks, didn't know that.

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You may want to give this guy a call. "The Old Carb Doctor".

828 659 1428 or 800 945 2272  He does carb restoration.

Did an old Zenith for me & did an excellent job. He's

close to you also  (N.C.)

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Would this condition be a cause to run with the choke about half closed?

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Yep, It runs fine with the choke half closed. Cutting off the air normally flowing through the throat of the carburator corrects the balance of fuel and air. At least that's what I think. I think you're getting the air around the throttle shaft that should have been coming through the throat. Not sure I made this clear. Are you having the same problems?

 

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My 41 Chrysler(original) runs fine with the choke about half closed.

Edited by windsor8

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If you need to pull the choke to half closed, you have a large vacuum leak down stream of the throttle plate. Much larger than could be accounted for by worn throttle bushings.  I would be hooking up a vacuum gauge to see what it is pulling at idle then go from there.  Check all the intake to block interfaces, the carb to manifold gasket to start with.  Vacuum wipers or electric?  Also if your vacuum advance diaphragm is ruptured that will cause a lean situation. You should be pulling 19 to 21 inches of vacuum with a steady needle all things being normal. Pulling the choke is artificially richening the mix by restricting the air portion of the ratio. Cutting half the air is more significant than worn bushings could be flowing.

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It's been a day since I got back on this but after starting fluid nor accetelyne created a disturbance while was engine was running I went to the distributor. Found that the weights were rusted in place so I had insufficient advance. Cleaned it all up and got the weights free. Spun distributor in my drill and weights moved outward. Reinstalled and got no performance change. So back to the carb. By chance another carburator showed up on Craigs List a couple of hours away. I drove over Saturday and picked it up. Oh, It was attached to an engine. Engine was in a '50 two door. It followed me home. Spent some hours and a can of carb cleaner on it and threw it on the car after setting the float level and oil-soaking the leather pump. Engine now runs great. Now time for an admission: When I took original carb off, the carb/manifold nuts were not much more than finger tight. But I thought the would carb cleaner application while running would have caught that. I might have two good carburators now. Now what to do with the coupe that I bought.  

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