The Ford Barn

oldford2 · 05-29-2019, 10:45 AM

If it idles good and takes acceleration my guess is dirt in the mains. When idling you are running on the idle jets. When accelerating you are running on the accelerating pump. On level ground and just cruising you are running on the main jets. Only takes a speck of dirt in a main to cause a stumble. Easy first check to pull the mains and inspect and blow them out.
John

philipswanson · 05-29-2019, 01:15 PM

Make sure you have fresh gas in it and no water. If in doubt, disconnect fuel line and take a sample for dirt and/or water. If so, the fuel tank needs to be dropped and cleaned out and the carb rebuilt.

Miner · 05-30-2019, 10:57 PM

Sorry for the delay in response. Been having some rough times and havent been able to get on site. I have all new coil, all new wiring in the car, new fuel tank, i did install electric pump in by rear tank for the vaporlock issue but I have not hooked up power yet, it is a flow through pump airtex I believe and ran all new lines when we built it. I ordered a rebuild kit for another carb I have laying here and gonna redo it and try that to see if I get same result. (I use the same carburetor on my 1940 so it wont be a waste if it doesnt fix it up) I appreciate you all on here and sorry I was away we are having some side effects from his treatment. I dont want to seem ungrateful for your help, I will keep you updated.

Flathead Fever · 05-30-2019, 11:58 PM

I can't see which pulley you have but the 8BA pulleys I have just have one raised dot for a timing mark. I think its at 4 degrees? I'm not sure what all those lines are on yours? Somebody probably marked them for TDC and maybe 4, 8 and 12 degrees and maybe another line for total advance but we have no way of knowing for sure what they did? Find the factory timing mark and time it using that. Disconnect the vacuum hose to the distributor and using your adjustable timing light measure the amount of centrifugal advance. Then apply a hand held vacuum pump to the vacuum advance and see how many degrees it is advancing the timing. Then check total advance with adjustable timing light. You need to make sure all that is working correctly. It needs to be done even if it is not causing the problem. Right now I'm not sure where you have it timed at? If anybody is thinking of buying a timing light make sure it is "adjustable" so you can measure the advance.

If its still having the problem it has to be fuel related. If it was an accelerator pump it would hesitate while you were depressing the pedal but once you had it pushed down the accelerator pump is done squirting. If the problem still continues while holding the pedal steady its not the accelerator pump. Then your down to plugged main jets, power valve not opening, wrong power valve, wrong main jets in the carb or not enough fuel being delivered to the carburetor. There is so much rust and crud in those old gas tanks, it's really easy for something to get plugged up.

I keep a separate gas can with a low pressure electric fuel pump that I can run the engine off of. I plug off the fuel line to the carb. Hook up my portable gas tank and go for a test ride. If the problem goes away I know the problem has to be between the carb and the gas cap. If its still there the problem is in the carb. Then I hook up the gas can to the engine's fuel pump. If the problem is still there I know its a faulty fuel pump. If the problem is not there it has to be in the line from the fuel pump to the tank or the tank has junk in it plugging the fuel line outlet. I use that little gas can setup quite a bit.
Its a quick way of diagnosing the fuel system under normal driving conditions.

The other way to check the pump, lines and tank is to take a vacuum and pressure reading on your fuel pump. Then disconnect the outlet fuel line from the pump and put it into a bottle and crank the engine for 15 second's and see how much volume of fuel your getting. Compare your results to the factory specifications. If the carb is old go ahead and rebuild it, a kit is cheap. Make sure "all" the passages are clear by taking a can of carb spray and forcing the end of the red straw against the each orifice and see if it sprays out into the center of the carb. Sometimes it can take a 120 lbs of shop air to blow something out that is stuck in an orifice. After rebuilding, holding the carb in its normal position and using your mouth, blow on the fuel inlet and see if you can blow air past the needle and seat. It should flow pretty easy. While your blowing flip the carb upside down. The needle and seat will close and you should no longer be able to blow through it. Stick t back on and adjust the air fuel mixture screws using a propane bottle.

JSeery · 05-31-2019, 07:39 AM

Quote:

Originally Posted by Flathead Fever

...Disconnect the vacuum hose to the distributor and using your adjustable timing light measure the amount of centrifugal advance. Then apply a hand held vacuum pump to the vacuum advance and see how many degrees it is advancing the timing. Then check total advance with adjustable timing light...

An 8ba distributor does not have centrifugal advance, vacuum only.

Ol' Ron · 06-01-2019, 01:46 PM

Sponsored Links (Register now to hide all advertisements)

I'm suppressed, he didn't know that?? Seams like a knowledgeable person.

05-29-2019, 10:45 AM	#21
oldford2 Senior Member Join Date: May 2010 Location: pittsfield, MA Posts: 2,086	Re: Ford flathead drivability If it idles good and takes acceleration my guess is dirt in the mains. When idling you are running on the idle jets. When accelerating you are running on the accelerating pump. On level ground and just cruising you are running on the main jets. Only takes a speck of dirt in a main to cause a stumble. Easy first check to pull the mains and inspect and blow them out. John

05-29-2019, 01:15 PM	#22
philipswanson Senior Member Join Date: Oct 2015 Location: Bonita, CA Posts: 1,374	Re: Ford flathead drivability Make sure you have fresh gas in it and no water. If in doubt, disconnect fuel line and take a sample for dirt and/or water. If so, the fuel tank needs to be dropped and cleaned out and the carb rebuilt.

05-30-2019, 10:57 PM	#23
Miner Junior Member Join Date: May 2019 Posts: 5	Re: Ford flathead drivability Sorry for the delay in response. Been having some rough times and havent been able to get on site. I have all new coil, all new wiring in the car, new fuel tank, i did install electric pump in by rear tank for the vaporlock issue but I have not hooked up power yet, it is a flow through pump airtex I believe and ran all new lines when we built it. I ordered a rebuild kit for another carb I have laying here and gonna redo it and try that to see if I get same result. (I use the same carburetor on my 1940 so it wont be a waste if it doesnt fix it up) I appreciate you all on here and sorry I was away we are having some side effects from his treatment. I dont want to seem ungrateful for your help, I will keep you updated.

05-30-2019, 11:58 PM	#24
Flathead Fever Senior Member Join Date: May 2010 Location: Yucaipa, CA Posts: 1,095	Re: Ford flathead drivability I can't see which pulley you have but the 8BA pulleys I have just have one raised dot for a timing mark. I think its at 4 degrees? I'm not sure what all those lines are on yours? Somebody probably marked them for TDC and maybe 4, 8 and 12 degrees and maybe another line for total advance but we have no way of knowing for sure what they did? Find the factory timing mark and time it using that. Disconnect the vacuum hose to the distributor and using your adjustable timing light measure the amount of centrifugal advance. Then apply a hand held vacuum pump to the vacuum advance and see how many degrees it is advancing the timing. Then check total advance with adjustable timing light. You need to make sure all that is working correctly. It needs to be done even if it is not causing the problem. Right now I'm not sure where you have it timed at? If anybody is thinking of buying a timing light make sure it is "adjustable" so you can measure the advance. If its still having the problem it has to be fuel related. If it was an accelerator pump it would hesitate while you were depressing the pedal but once you had it pushed down the accelerator pump is done squirting. If the problem still continues while holding the pedal steady its not the accelerator pump. Then your down to plugged main jets, power valve not opening, wrong power valve, wrong main jets in the carb or not enough fuel being delivered to the carburetor. There is so much rust and crud in those old gas tanks, it's really easy for something to get plugged up. I keep a separate gas can with a low pressure electric fuel pump that I can run the engine off of. I plug off the fuel line to the carb. Hook up my portable gas tank and go for a test ride. If the problem goes away I know the problem has to be between the carb and the gas cap. If its still there the problem is in the carb. Then I hook up the gas can to the engine's fuel pump. If the problem is still there I know its a faulty fuel pump. If the problem is not there it has to be in the line from the fuel pump to the tank or the tank has junk in it plugging the fuel line outlet. I use that little gas can setup quite a bit. Its a quick way of diagnosing the fuel system under normal driving conditions. The other way to check the pump, lines and tank is to take a vacuum and pressure reading on your fuel pump. Then disconnect the outlet fuel line from the pump and put it into a bottle and crank the engine for 15 second's and see how much volume of fuel your getting. Compare your results to the factory specifications. If the carb is old go ahead and rebuild it, a kit is cheap. Make sure "all" the passages are clear by taking a can of carb spray and forcing the end of the red straw against the each orifice and see if it sprays out into the center of the carb. Sometimes it can take a 120 lbs of shop air to blow something out that is stuck in an orifice. After rebuilding, holding the carb in its normal position and using your mouth, blow on the fuel inlet and see if you can blow air past the needle and seat. It should flow pretty easy. While your blowing flip the carb upside down. The needle and seat will close and you should no longer be able to blow through it. Stick t back on and adjust the air fuel mixture screws using a propane bottle.

06-01-2019, 01:46 PM	#26
Ol' Ron Senior Member Join Date: May 2010 Location: Chester Vt Posts: 8,860	Re: Ford flathead drivability Sponsored Links (Register now to hide all advertisements) I'm suppressed, he didn't know that?? Seams like a knowledgeable person.