The Ford Barn

Daves55Sedan · 02-07-2016, 06:36 PM

I noticed that my original '55 Ford EBU carb leaked gas out around the valve shaft (where it connects to linkage actuator) after engine is shut off. Engine will not start unless enough time has passed for leak to dry up.
So, I took that carb off and put on a Holley 2100 (identical to the Ford EBU carb). It has a new rebuild kit from Daytona parts. It leaks exactly the same way. Gas pours out on the heat riser passage of the intake manifold for about five minutes. Looking inside the carb after engine is shut off, the two valve plates at the bottom are very wet with gas, but I cant see gas dripping from anywhere.
The Holley carb surges slightly at idle speed. I took the top off the carb and checked the float setting. It is good and the engine does not die when I come to a stop sign.
I used a vacuum gage to adjust the idle/fuel mixture screws and noticed the best intake manifold vacuum I could get was only 18". It should be 20".
I don't know if that is related to the leak or the surging.
The fuel pump is 2 years old and it is a dual-action fuel/vacuum type. Fuel filter is a see-through type and looks good.
Any suggestions?

Alaska Jim · 02-07-2016, 07:34 PM

Poss. fuel cap not venting, or wrong cap, poss. fuel press to high. 18" of vac. is not that bad. other than that I will have to see what others with more experience say.

JeffB2 · 02-08-2016, 02:11 AM

You should only be getting about 2.5 psi fuel pressure with that pump if it is exceeding that you may have to add a regulator. This issue has become more and more common since companies are using off-shore manufacturers.

scicala · 02-08-2016, 11:42 AM

Quote:

Originally Posted by JeffB2

You should only be getting about 2.5 psi fuel pressure with that pump if it is exceeding that you may have to add a regulator. This issue has become more and more common since companies are using off-shore manufacturers.

The 1955 Ford shop manual says 4.0 to 5.0 PSI fuel pump pressure.

Maybe a flathead would be lower.

Sal

Sid · 02-08-2016, 12:11 PM

If these carbs. were rebuilt using the power valves designed for today's Holley they will not work properly. The tip will interfere with the inside of the float bowl and keep the power valve from shutting off completely.Also you may have to lower your float level slightly as today's Ethanol gas has more expansion with heat. To check for a power valve problem turn the air mixture screws all the way in,if it keeps running that is your problem.

Daves55Sedan · 02-08-2016, 06:14 PM

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Quote:

Originally Posted by Sid

The tip will interfere with the inside of the float bowl and keep the power valve from shutting off completely.

That's something worth checking into. Never thought of this.

Daves55Sedan · 02-08-2016, 06:12 PM

Quote:

Originally Posted by scicala

The 1955 Ford shop manual says 4.0 to 5.0 PSI fuel pump pressure.
Maybe a flathead would be lower. Sal

The EBU carb is identical to the flathead carb from the top of the valve body on up. In fact everything from the top of the valve body on up is interchangeable on the flathead carbs and they use the same rebuild kit. Thus; fuel inlet, needle and float assemblies are same/interchangeable.
There does not seem to be a problem with the float operation. As far a fuel pump, my concern would rather be the possibility that the vacuum diaphragm might be causing a problem. If the vac diaphragm is ruptured, could it cause manifold vacuum to be reduced? I would think not because it is a closed loop system via the tubing, right? unless the top chamber in the fuel pump is not completely sealed off from outside air ???

scicala · 02-09-2016, 01:44 PM

"The EBU carb is identical to the flathead carb from the top of the valve body on up. In fact everything from the top of the valve body on up is interchangeable on the flathead carbs and they use the same rebuild kit. Thus; fuel inlet, needle and float assemblies are same/interchangeable."

Daves55Sedan, I was thinking the flathead fuel pumps were less pressure because the fuel demand is less on a flathead, because of having a lot less HP than the 272 Y-Block, and not because it won't hold the higher pressure.

Sal

Daves55Sedan · 02-10-2016, 11:34 PM

I removed the power valve and used an old spark plug boot connected to a MityVac to test the operation of the valve. It appears that the plunger begins to release somewhere around 6-7 inches vacuum. Its hard to get that reading exact because it is difficult to release the vacuum slow enough with the mityvac and watch the plunger at the same time, but the specs call for the vacuum to decrease to anywhere from 9-7.5", so I am calling it good. However that does NOT mean that the valve seat inside the power valve is not damaged which could cause fuel leakage during idle speed or when engine is shut off.
I am going to try to test the valve seat for leakage tomorrow.

scicala · 02-11-2016, 10:40 AM

Quote:

Originally Posted by Daves55Sedan

I removed the power valve and used an old spark plug boot connected to a MityVac to test the operation of the valve. It appears that the plunger begins to release somewhere around 6-7 inches vacuum. Its hard to get that reading exact because it is difficult to release the vacuum slow enough with the mityvac and watch the plunger at the same time, but the specs call for the vacuum to decrease to anywhere from 9-7.5", so I am calling it good. However that does NOT mean that the valve seat inside the power valve is not damaged which could cause fuel leakage during idle speed or when engine is shut off.
I am going to try to test the valve seat for leakage tomorrow.

You need to get a good seal and see if the power valve holds vacuum too. It could have a small leak in the diaphragm and still open around 6 to 7" of vacuum. Very unlikely that the valve itself is leaking. The only way fuel gets past the valve and dumped into the manifold is with a bad diaphragm, and not through the valve seat.

Sal

Daves55Sedan · 02-10-2016, 11:39 PM

Oh, and BTW, the top of the power valve plunger does not hit the recess in the float chamber when it is assembled in the bottom of the main body.
If it did, that situation might be remedied by adding another round gasket between the valve and main body, but you would need to make certain that the bottom of the power valve did not hit the vacuum recess in the valve body when re-assembled onto the main body.

Daves55Sedan · 02-10-2016, 11:43 PM

I also noticed that the accelerator pump rubber cup diameter is not large enough to touch the bore that it fits into on the Ford EBU carb, and wondered if this could be part of the problem. On the Holley 2100 carb, the accelerator pump rubber cup does fit snugly into the bore.
The accell pump on the Ford carb is new from a Daytona parts kit. ??????

Sid · 02-11-2016, 11:00 AM

I think you may have a percolating problem. I would try dropping the float level slightly especially if the seepage problem is basically when engine is hot. As far as the accelerator pump if you can find an old original one you can soak it in hot water to make it pliable again and reuse it especially if it is leather

Daves55Sedan · 02-11-2016, 03:53 PM

Quote:

Originally Posted by Sid

I think you may have a percolating problem. I would try dropping the float level slightly especially if the seepage problem is basically when engine is hot. As far as the accelerator pump if you can find an old original one you can soak it in hot water to make it pliable again and reuse it especially if it is leather

Sid; I already have the float adjusted so that there is only 1/16 inch between bottom of float and the raised boss in bottom of the main body where that front valve body mounting screw resides. It can't go any lower or the float will hit that surface.
Leakage occurs even if engine is cold after engine is shut off.
I did find a accel pump with a leather piston that had been oiled as recommended by rebuild kit instructions. It's outside diameter also falls short of the accel pump bore. I stretched it all around with my fingers just slightly and now it fits more tightly in the bore BUT how long will that last???

Daves55Sedan · 02-11-2016, 03:59 PM

I went into the early V8 forum where I thought there might be a lot more about this from people who have flathead V8 engines.
Many folks seem to fault the accelerator pump and it has also been suggested that the little ball held into a hole in the bottom of the accelerator pump bore could be leaking.
Can anyone shed light on this? There are TWO holes in the bottom of the bore. One is plugged by the ball and the other one is open. To my knowledge, that's the way it should be. I think the open hole connects back to the idle/fuel passages, right?

scicala · 02-11-2016, 04:12 PM

Dave,

There is a small spring behind the leather on the accelerator pump. You can carefully roll the leather back and take out the spring. Then stretch it slightly to put more tension on the back side of the leather to help make it fit the bore better.

As far as the two holes on the bottom of the pump bore, the one with the ball lets new fuel come into the bore, when the pump is pulled up, and shuts off the ball when it goes down. The open hole is the path to the accel pump nozzle that squirts into the carb throat when the piston goes down. Not into an idle channel.

There also should be a round wire at the bottom of the bore to keep the ball from coming out of it's pocket.

If fuel is coming out of the throttle shaft holes in the base of the carb, it's because of a high fuel level, from either dirt in the fuel valve (float valve), too much fuel pressure, or a float that is sinking from fuel inside. This is assuming the carb isn't percolating from heat after shut down (which I believe you said was not the case.

Sal

Hot Rod Reverend · 02-11-2016, 04:25 PM

The open hole is what is pushing the fuel back into the fuel bowl and giving an extra shot of fuel into your bores. The check ball hole is for filling your accelerator pump chamber, therefore when the leather plunger goes down the check ball seals the passage giving pressure to the fuel you are trying to squeeze through the open hole.

Even back in the early 90s when I drove my 55 every day, and there was no ethanol gas, my 2100 would do what you are describing. The only "fix" to the leakage was to remove the butterflies and drill out the bore of the throttle body so I could put an o ring around the shaft. This stopped the leakage on the intake.

The issue with not starting was two fold I believe, 1:the carb leaked on the interior and flooded the intake, and 2:the carb emptied itself of the fuel in the bowl because of heat from the intake and since the fuel was no longer moving after the engine stopped (a good thermal insulator helped this situation.) With today's ethanol fuel the heat soak problem is worse. I would recommend you do two things, get a good thermal insulator for your carb/intake and block off the exhaust passage in your intake runners if you have not done so already.

On the insulator, the old Bakelite is your best bet.

Daves55Sedan · 02-11-2016, 11:31 PM

Sal and HRR; I see what the two holes are for now by looking at the passages underneath. You are right.
I removed the round wire clip at bottom of the accelerator pump bore and turned the carb upside down. I had to hit the carb with my hand till the ball fell out. Blew air through a small straw from the hole in the pump chamber that feeds to the hole where the ball goes. Plenty good air flow there. I installed a new ball and reinstalled the wire clip.
Wear at the main valve shaft seems minimal. I think the spec calls for maximum of .065" play. If there were a lot of wear here, it could be both a source of fuel and vacuum leakage.
I installed a thick phenolic spacer under the carb about 25 years ago. There's never been a problem with gas boiling since then.
It has a new float needle, seat and gasket from a Daytona parts kit, but I am going to take it all apart tomorrow and clean the float parts good and re-install. After that I am going to hold the throttle closed while pouring gas into the float chamber to see if there is leakage. To be continued.

Daves55Sedan · 02-22-2016, 04:37 PM

Well, I don't know what was the cause of the problem, but it must have been something I did during the process of re-rebuilding that fixed it. Now the Ford EBU carb is working properly, does not leak and the engine starts immediately regardless how long I run the engine.
That darned old Holley 2100, I don't know about though. I never did like it. The Ford EBU has always been superior to the Holley. Anyway, the car runs again, until next time.

02-07-2016, 06:36 PM	#1
Daves55Sedan Senior Member Join Date: May 2010 Location: Granite City, Illinois Posts: 3,008	55 Ford carb problem I noticed that my original '55 Ford EBU carb leaked gas out around the valve shaft (where it connects to linkage actuator) after engine is shut off. Engine will not start unless enough time has passed for leak to dry up. So, I took that carb off and put on a Holley 2100 (identical to the Ford EBU carb). It has a new rebuild kit from Daytona parts. It leaks exactly the same way. Gas pours out on the heat riser passage of the intake manifold for about five minutes. Looking inside the carb after engine is shut off, the two valve plates at the bottom are very wet with gas, but I cant see gas dripping from anywhere. The Holley carb surges slightly at idle speed. I took the top off the carb and checked the float setting. It is good and the engine does not die when I come to a stop sign. I used a vacuum gage to adjust the idle/fuel mixture screws and noticed the best intake manifold vacuum I could get was only 18". It should be 20". I don't know if that is related to the leak or the surging. The fuel pump is 2 years old and it is a dual-action fuel/vacuum type. Fuel filter is a see-through type and looks good. Any suggestions?

02-07-2016, 07:34 PM	#2
Alaska Jim Senior Member Join Date: May 2010 Location: Palmer, Alaska Posts: 1,587	Re: 55 Ford carb problem Poss. fuel cap not venting, or wrong cap, poss. fuel press to high. 18" of vac. is not that bad. other than that I will have to see what others with more experience say.

02-08-2016, 02:11 AM	#3
JeffB2 Senior Member Join Date: May 2010 Location: Phoenix,AZ Posts: 1,417	Re: 55 Ford carb problem You should only be getting about 2.5 psi fuel pressure with that pump if it is exceeding that you may have to add a regulator. This issue has become more and more common since companies are using off-shore manufacturers.

02-08-2016, 12:11 PM	#5
Sid Senior Member Join Date: May 2010 Location: Rathdrum Idaho Posts: 740	Re: 55 Ford carb problem If these carbs. were rebuilt using the power valves designed for today's Holley they will not work properly. The tip will interfere with the inside of the float bowl and keep the power valve from shutting off completely.Also you may have to lower your float level slightly as today's Ethanol gas has more expansion with heat. To check for a power valve problem turn the air mixture screws all the way in,if it keeps running that is your problem. Last edited by Sid; 02-08-2016 at 12:48 PM.

02-09-2016, 01:44 PM	#8
scicala Senior Member Join Date: Jun 2010 Location: Detroit suburb, MI Posts: 3,794	Re: 55 Ford carb problem "The EBU carb is identical to the flathead carb from the top of the valve body on up. In fact everything from the top of the valve body on up is interchangeable on the flathead carbs and they use the same rebuild kit. Thus; fuel inlet, needle and float assemblies are same/interchangeable." Daves55Sedan, I was thinking the flathead fuel pumps were less pressure because the fuel demand is less on a flathead, because of having a lot less HP than the 272 Y-Block, and not because it won't hold the higher pressure. Sal

02-10-2016, 11:34 PM	#9
Daves55Sedan Senior Member Join Date: May 2010 Location: Granite City, Illinois Posts: 3,008	Re: 55 Ford carb problem I removed the power valve and used an old spark plug boot connected to a MityVac to test the operation of the valve. It appears that the plunger begins to release somewhere around 6-7 inches vacuum. Its hard to get that reading exact because it is difficult to release the vacuum slow enough with the mityvac and watch the plunger at the same time, but the specs call for the vacuum to decrease to anywhere from 9-7.5", so I am calling it good. However that does NOT mean that the valve seat inside the power valve is not damaged which could cause fuel leakage during idle speed or when engine is shut off. I am going to try to test the valve seat for leakage tomorrow.

02-10-2016, 11:39 PM	#11
Daves55Sedan Senior Member Join Date: May 2010 Location: Granite City, Illinois Posts: 3,008	Re: 55 Ford carb problem Oh, and BTW, the top of the power valve plunger does not hit the recess in the float chamber when it is assembled in the bottom of the main body. If it did, that situation might be remedied by adding another round gasket between the valve and main body, but you would need to make certain that the bottom of the power valve did not hit the vacuum recess in the valve body when re-assembled onto the main body.

02-10-2016, 11:43 PM	#12
Daves55Sedan Senior Member Join Date: May 2010 Location: Granite City, Illinois Posts: 3,008	Re: 55 Ford carb problem I also noticed that the accelerator pump rubber cup diameter is not large enough to touch the bore that it fits into on the Ford EBU carb, and wondered if this could be part of the problem. On the Holley 2100 carb, the accelerator pump rubber cup does fit snugly into the bore. The accell pump on the Ford carb is new from a Daytona parts kit. ??????

02-11-2016, 11:00 AM	#13
Sid Senior Member Join Date: May 2010 Location: Rathdrum Idaho Posts: 740	Re: 55 Ford carb problem I think you may have a percolating problem. I would try dropping the float level slightly especially if the seepage problem is basically when engine is hot. As far as the accelerator pump if you can find an old original one you can soak it in hot water to make it pliable again and reuse it especially if it is leather

02-11-2016, 03:59 PM	#15
Daves55Sedan Senior Member Join Date: May 2010 Location: Granite City, Illinois Posts: 3,008	Re: 55 Ford carb problem I went into the early V8 forum where I thought there might be a lot more about this from people who have flathead V8 engines. Many folks seem to fault the accelerator pump and it has also been suggested that the little ball held into a hole in the bottom of the accelerator pump bore could be leaking. Can anyone shed light on this? There are TWO holes in the bottom of the bore. One is plugged by the ball and the other one is open. To my knowledge, that's the way it should be. I think the open hole connects back to the idle/fuel passages, right?

02-11-2016, 04:12 PM	#16
scicala Senior Member Join Date: Jun 2010 Location: Detroit suburb, MI Posts: 3,794	Re: 55 Ford carb problem Dave, There is a small spring behind the leather on the accelerator pump. You can carefully roll the leather back and take out the spring. Then stretch it slightly to put more tension on the back side of the leather to help make it fit the bore better. As far as the two holes on the bottom of the pump bore, the one with the ball lets new fuel come into the bore, when the pump is pulled up, and shuts off the ball when it goes down. The open hole is the path to the accel pump nozzle that squirts into the carb throat when the piston goes down. Not into an idle channel. There also should be a round wire at the bottom of the bore to keep the ball from coming out of it's pocket. If fuel is coming out of the throttle shaft holes in the base of the carb, it's because of a high fuel level, from either dirt in the fuel valve (float valve), too much fuel pressure, or a float that is sinking from fuel inside. This is assuming the carb isn't percolating from heat after shut down (which I believe you said was not the case. Sal

02-11-2016, 04:25 PM	#17
Hot Rod Reverend Senior Member Join Date: May 2010 Location: Lancaster, CA Posts: 947	Re: 55 Ford carb problem The open hole is what is pushing the fuel back into the fuel bowl and giving an extra shot of fuel into your bores. The check ball hole is for filling your accelerator pump chamber, therefore when the leather plunger goes down the check ball seals the passage giving pressure to the fuel you are trying to squeeze through the open hole. Even back in the early 90s when I drove my 55 every day, and there was no ethanol gas, my 2100 would do what you are describing. The only "fix" to the leakage was to remove the butterflies and drill out the bore of the throttle body so I could put an o ring around the shaft. This stopped the leakage on the intake. The issue with not starting was two fold I believe, 1:the carb leaked on the interior and flooded the intake, and 2:the carb emptied itself of the fuel in the bowl because of heat from the intake and since the fuel was no longer moving after the engine stopped (a good thermal insulator helped this situation.) With today's ethanol fuel the heat soak problem is worse. I would recommend you do two things, get a good thermal insulator for your carb/intake and block off the exhaust passage in your intake runners if you have not done so already. On the insulator, the old Bakelite is your best bet. __________________ Lancaster, California Visit hotrodreverend.com to view hundreds of pictures and videos of the build of the 1955 Ford Club Sedan!

02-11-2016, 11:31 PM	#18
Daves55Sedan Senior Member Join Date: May 2010 Location: Granite City, Illinois Posts: 3,008	Re: 55 Ford carb problem Sal and HRR; I see what the two holes are for now by looking at the passages underneath. You are right. I removed the round wire clip at bottom of the accelerator pump bore and turned the carb upside down. I had to hit the carb with my hand till the ball fell out. Blew air through a small straw from the hole in the pump chamber that feeds to the hole where the ball goes. Plenty good air flow there. I installed a new ball and reinstalled the wire clip. Wear at the main valve shaft seems minimal. I think the spec calls for maximum of .065" play. If there were a lot of wear here, it could be both a source of fuel and vacuum leakage. I installed a thick phenolic spacer under the carb about 25 years ago. There's never been a problem with gas boiling since then. It has a new float needle, seat and gasket from a Daytona parts kit, but I am going to take it all apart tomorrow and clean the float parts good and re-install. After that I am going to hold the throttle closed while pouring gas into the float chamber to see if there is leakage. To be continued.

02-22-2016, 04:37 PM	#19
Daves55Sedan Senior Member Join Date: May 2010 Location: Granite City, Illinois Posts: 3,008	Re: 55 Ford carb problem Well, I don't know what was the cause of the problem, but it must have been something I did during the process of re-rebuilding that fixed it. Now the Ford EBU carb is working properly, does not leak and the engine starts immediately regardless how long I run the engine. That darned old Holley 2100, I don't know about though. I never did like it. The Ford EBU has always been superior to the Holley. Anyway, the car runs again, until next time.