Topic: Engine lope


silverchief    -- 04-14-2024 @ 2:02 PM
  For the past several years my 49 flathead has run great. Strictly stock excepting a full time electric fuel pump.
Routinely starts upon half turn of the crank, idles whisper quiet at 500 rpm and at 50 mph cruises and accelerates smoothly.
Every winter I fill it with high quality gas, add a little Sta Bil, pull it into the garage, and shut the fuel pump off, letting it idle until the carb bowl runs dry.

Every Spring, (excepting this one, ) it starts quickly and performs as usual. Unlike previous seasons, today it started easily, but it idles very rough until it warms up, and then it settles into a rough lope. The only slight improvement comes if I push the idle way above 600 rpm. This at least shows the carb is getting plenty of fuel.

Plugs, wiring, and all stock distributor innards were replaced last summer, resulting in the same great performance until I put it away.

Before I start guessing and yanking I thought it might be a good idea to listen to the voice of experience.

Thanks very much

Silverchief

This message was edited by silverchief on 4-27-24 @ 10:33 AM


TomO    -- 04-14-2024 @ 5:32 PM
  Try driving it for a couple of hours. The fuel jets could have a little varnish in them from sitting ove the winter.

Tom


silverchief    -- 04-15-2024 @ 7:55 AM
  Good idea Tom. Will do.


Ford1938    -- 04-15-2024 @ 11:36 AM
  Shut the pump off run till bowl is empty they can of carburetor cleaner on top of carburetor bowl vent spray carburetor cleaner thought vent till bowl is and let set for half hr. keeping bowl full that will clean jets start and drive away>


GK1918    -- 04-15-2024 @ 1:09 PM
  Maybe maybe not but my car acts like that. You said spring don't know where you live, but our spring is
despicable. It starts instant (no choke either) then starts to run like cr*p go to race it up can't even press the pedal. I already know. open hood sure enough carburetor throttle body solid ice. Here it doesn't have to be freezing just damp 40 degrees or so. My dump truck with a 391 FT takes a 1/2 hr before I can move it. even in a garage with no heat will do it. Just A sayin


silverchief    -- 04-25-2024 @ 1:11 PM
  Found the culprit. Just not sure how to arrest him.

Been under the hood the past 4 days going through the ignition system, all connections from the battery, including grounds, wiring, plugs, inside of distributor, etc. During this entire time not once did I smell or see the slightest hint of gasoline, excepting most plug holes were wet and all plugs were black with soot. Also, yesterday for the first time since I've owned the car I got blue smoke when it was at a very rough and short idle.

Today, I did a compression check, which involved repeated cranking of the engine with all plugs out. Immediately afterward the culprit made his first appearance, raw gasoline soaking the gaskets between the carb top and its bottom., and between the bottom half and the intake manifold. Touching anywhere near those areas brings up raw gas.

I removed the top half and see no evidence af a sticking needle or fuel in the float. Yesterday was the last time the engine was under power, and this afternoon, fuel in the bowl is exactly 1 and 1/4 inches below its top.

Lifting the float to its closed position reveals gasoline powdery residue exactly half way up all the way around. No higher.

I have read more than a few threads about a worn "power valve" resulting in what I am experiencing. Thought I would start there but have no idea what it looks like, where to find it, or how to replace it.

All suggestions are appreciated.

This message was edited by silverchief on 4-25-24 @ 1:25 PM


carcrazy    -- 04-25-2024 @ 3:18 PM
  Your '49 Ford carburetor contains three main castings, they are from top to bottom:
Air Horn which contains the choke plate and fuel inlet.
Main Body which houses the fuel bowl, main jets and power valve.
Throttle Body which contains the throttle plates and idle mixture adjusting screws.

To gain access to the power valve, first remove the carburetor from the intake manifold and then remove the throttle body from the bottom of the main body. Turn the main body upside down and you will see the power valve. The power valve can then be removed by using an adjustable wrench.

When you install a new power valve, be sure to use a new gasket and make sure the power valve and gasket fit properly and provide a good seal to the main body.

Use new carburetor gaskets to replace all of the ones you have previously disturbed and reassemble and reinstall the carburetor on the engine.

If you are still having problems, let us know and we will advise of additional actions to take.


sarahcecelia    -- 04-26-2024 @ 2:47 PM
  How can I shut the pump OFF on my 1950 car to do that????? I would take the top off the carb, take the gas in the fuel bowl with a clean rag, the then- do the carb cleaner spray.NO???

Regards, Steve Lee


silverchief    -- 04-27-2024 @ 10:14 AM
  Trying to determine the cause of my carb flooding on my 49 flathead, which at this point appears to be the cause off my previously described engine problems.

As suggested I removed the carb from the engine.                    

The air horn housing has a mental tag attached that reads AUTOLITE 8RT 9510 F That portion that covers the float bowl has I R 332 molded on the underside.

The main body bears a Ford script, and that part of the housing that contains the power valve bears a letter H.

On the lower third of the housing is molded the letters GF and the numeral 8

The lower end of power valve itself does not hold "leather" but rather a soft blue rubber cup. It looks and feels to be in nice shape, but I don't know how that should appear, and if I should replace it just to be safe.

At this point I'm not certain if the carb was manufactured by Autolite, Ford, or Holley.and thus how to order a new power valve.

Appreciate all suggestions.

This message was edited by silverchief on 4-27-24 @ 10:37 AM


carcrazy    -- 04-27-2024 @ 5:31 PM
  The cause of you carburetor flooding may be due to the electric fuel pump putting out too much fuel pressure.

Flathead carburetors like to have about 2.5 - 3.0 PSI fuel pressure. More than that can overpower the needle and seat system to maintain proper fuel level in the float bowl.

The part you describe as having a rubber part on the bottom of it sound like the accelerator pump.

You can purchase a new Carburetor Rebuilding Kit from C&G Auto Parts which includes a new power valve, accelerator pump and the gaskets required to reassemble the carburetor.

The kit they show for your application is P.N. 59A-9590

https://cgfordparts.com/catalogsearch/result/?q=carburetor%20rebuild%20kit&finder%5B1%5D=4778&finder%5B2%5D=4891&finder%5B3%5D=5110&find=find


silverchief    -- 04-28-2024 @ 11:20 AM
  Carcrazy

Thanks for the helpful information. T think you are right about the accelerator pump - where is the "power" valve located in the carb?


carcrazy    -- 04-28-2024 @ 3:55 PM
  The power valve is on the bottom side of the fuel bowl. It is visible once you separate the main body from the throttle body. It is approximately one inch in diameter with four flat sides that can easily be removed with an adjustable wrench.


silverchief    -- 04-29-2024 @ 11:09 AM
  Thanks very much!


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