Carburetor Frustration

[RonLey]

I haven't driven my '28 Roadster for a while but this weekend went out to take a ride. I have an original Holley (H/H) carburetor on the car which had run fine the last time I drove it. This time when I opened the gas valve gasoline came running out. Ok, figured I had some trash under the needle. I have a ball type needle/seat.

Took the carb off and cleaned everything and made sure all of the passages were clear. I use all new gaskets and put the carb back together. I put it back and it leaks. I pull the bowl off expecting to see gasoline up to the rim but the gas level is appropriate for the height of the float. I have the wife open the gas valve while holding the float up and it doesn't leak. So it doesn't appear that I have leakage there. I checked the float level and I am at 1" to the float rib.

I am about ready to order another needle/seat but I can't find anything wrong with this one. Any ideas would be welcome.

Ron

[BRENT in 10-uh-C]

Originally Posted by RonLey

I haven't driven my '28 Roadster for a while but this weekend went out to take a ride. I have an original Holley (H/H) carburetor on the car which had run fine the last time I drove it. This time when I opened the gas valve gasoline came running out. Ok, figured I had some trash under the needle. I have a ball type needle/seat.

Took the carb off and cleaned everything and made sure all of the passages were clear. I use all new gaskets and put the carb back together. I put it back and it leaks. I pull the bowl off expecting to see gasoline up to the rim but the gas level is appropriate for the height of the float. I have the wife open the gas valve while holding the float up and it doesn't leak. So it doesn't appear that I have leakage there. I checked the float level and I am at 1" to the float rib.

I am about ready to order another needle/seat but I can't find anything wrong with this one. Any ideas would be welcome.

Ron

It leaks 'where'? If the float is not damaged where it can float with enough pressure to close off the valve (needle) against the seat, then you should not have any issue. Turn the carb. top over and with the valve in against the seat just by gravity, drop some fuel in around the valve to see if it will hold the fuel and not let it bypass. If it does, you know where your problem is.

[larrys40]

Ron

You probably have some dirt in the needle/seat. I would take the carb apart and make sure the floatneedle and seat, and float level is correct and all is ok there. Float level should be 5/8 inverted from top of float to machine surface of carb top . I would also put a vacuum pump on the needle and seat. If it won't hold vacuum the seat will leak, if it does it should be ok. Vitons tips are good if you use it all the time as the seem to like constant wetness and use . The metal valves are ok if the seat. Unfortunately I don't think there's a perfect needle and seat out there right now . I ever so slight stake on a metal seat can sometimes fix one, but never do that to a viton, as you will ruin it.
Good luck hope that all helps . Just know that if you put you finger in the carb throat and it is wet that either your float level is too high, float sunk, as the fuel I tipping. The jets. There's other things to but for the most part that should help
Larry Shepard

[Synchro909]

I don't know anything about the Holley carby. Are they cast iron or die cast muck metal. If they are the latter, maybe the problem is a crack/hole in the body somewhere. Is there any physical damage to the body, even has it been strained some time during its life to cause a weakness.
If you have another carby of any sort (appropriate), maybe you just use it.

[RonLey]

This is the same as Zenith style carburetor that was made by Holley and marked H instead of Z.

[jmeckel]

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Depending on the quality of the ball type float valve that maybe your issue. A good ball valve is a good thing, however the ones I have tried in the recent past are junk. A original type float valve that you have carefully checked to make sure it is sealing, and sometimes lapped with toothpaste to make sure it seals, is the best current option IMO. Also check the float for a "dimple" that gets wore into them over time by the float valve. You can repair this issue by carefully filling it in with solder. I would remove the screen and the float valve and clean the passage very well, I have seen a lot of rust and dirt in this area in many of the carbs I have restored.

[Tom Wesenberg]

About 5 years ago my 28 suddenly acted like it was running rich from too much gas, so I turned off the gas valve until the engine started to die, then turned the gas back on. The inrush of gas cleaned out the needle and seat, and it's run fine ever since.

[Fred]

Originally Posted by RonLey

This is the same as Zenith style carburetor that was made by Holley and marked H instead of Z.

The "Zenith-2" is also made by Holley and marked as such..

[Mike V. Florida]

Please be explicit as to what gaskets you replaced. If the main jet is too low it will leak.

Read Tom Endy's article on Carbs look at page 12, 13 about leaks.

Orange County Model A Ford Club

[oj]

If the fuel in the bowl is correct for the float level then I'd say the needle & seat are working proper and the leak must be before the needle & seat, the inlet fitting.
I made a carburetor holder with allthread that holds the carb above my parts cleaner so I can see the bottom of it. I turn on 'fuel' to it and can see what happens.

[H. L. Chauvin]

Hi Ron,

1. All good suggestions above; & maybe think of it this way.

2. Your carburetor leaks when it is "assembled" & "installed".

3. "Everything" exposed in plain view looks "great" when your carburetor is "not" "assembled" & "installed".

4. When "assembled" & "installed", you do not have X-ray vision to see through cast iron to view the dark inside to verify the height of the fuel when the carburetor is "assembled" & "installed".

5. You could use the clear, small glass jar technique to have light inside the jar to "see" the fuel level when the carburetor is "assembled" & "installed"; or,

6. You could get the very accurate, "large" diameter fuel level gauge from Renner's Model A parts, where you can verify your carburetor's accurate fuel level inside when the carburetor "assembled" & "installed".

7. A few possible causes of a float not performing correctly could be:

a. Your float was formerly repaired with solder & with solder drippings inside and/or outside of the float, this additional solder weight causes your float to be heavy & not floating high enough to close the float valve; and/or,

b. The steel arms holding the float pin are too far opened & they allow the float to move side to side, thus causing the float to "not" easily rotate & stick in the open position; and/or,

c. For whatever reason(s) one can imagine, you may see that after all precautions, your float just needs to be "readjusted" to obtain the proper fuel level.

8. What usually works in a similar area when you cannot find your Model A keys or anything else in the dark -- quit feeling around & just turn the light "ON".

Just hope this helps.

[Bob C]

This is a long shot but I saw one once that the cap jet fell out.

Bob