The Ford Barn

howie123 · 07-21-2013, 08:44 AM

On a recent drive in my Model A speedster, the clutch release arm broke. I understand this is not uncommon but I may have initiated the problem when I installed the arm with a reproduction pin which I believe was probably too tight. I got a new arm and pin from Snyders. It is the slightly longer version. I was more careful with the installation and all is fine. I couldn't believe how much easier the clutch works. When they say 30% decrease in pressure, I think it's true.
Now for the question. The speedster has a stock 28 engine, Zenith carburetor, electric fuel pump with regulator. It starts easily and runs great. When I get up to speed it does make an occasional spittiing noise and I get black sooty spots on the right rear wheel and right side of differential. Is this a matter of running rich? What would be the most logical things to start checking. Thanks. Howie

pat in Santa Cruz · 07-21-2013, 10:40 AM

sounds rich to me. You should be getting 18-20 mpg on the highway. The first thing I would check is fuel pump pressure. If its higher than 1.5 psi, the float is being over ridden by the pump. Do not rely on the regulator dial, use an accurate pressure gauge. I cannot see why you need a pump on an updraft carburetor unless you are not using the cowl fuel tank.

Also, The float in the carb might be set too high or could be sinking, the main jet could be worn too large, there could be a leak from one of the jets, or your GAV could be too far open or have a leaking seat. If you're not the carburetor tech you would like to be, Berts sells some really well done rebuilt Zeniths with flow tested jets.

Purdy Swoft · 07-21-2013, 10:50 AM

It very well could be that an adjusting needle seat was accidently installed in place of the compensator jet , that goes in the left rear carburetor bowl . the two parts look very similiar and have been known to get mixed up. It happened to me once over twenty years ago. After installing the correct compensator jet, the problem was solved. You can observe pictures of these parts on pages 61 and 63 of the newest Brattons catalog.

howie123 · 07-22-2013, 07:04 PM

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Thanks for the input. I should have been more clear. My gas tank is behind the seat and just a little too low so it runs out of gas going up a hill. I will start checking things out one at a time. I have thought of adding a line parallel to the fuel pump and only use the pump on hills. Would it also be necessary to bypass the regulator or would the fuel run through it? Thanks again. Howie

07-21-2013, 08:44 AM	#1
howie123 Senior Member Join Date: Jul 2010 Location: Eau Claire, WI Posts: 113	Recent experience and an unrelated question On a recent drive in my Model A speedster, the clutch release arm broke. I understand this is not uncommon but I may have initiated the problem when I installed the arm with a reproduction pin which I believe was probably too tight. I got a new arm and pin from Snyders. It is the slightly longer version. I was more careful with the installation and all is fine. I couldn't believe how much easier the clutch works. When they say 30% decrease in pressure, I think it's true. Now for the question. The speedster has a stock 28 engine, Zenith carburetor, electric fuel pump with regulator. It starts easily and runs great. When I get up to speed it does make an occasional spittiing noise and I get black sooty spots on the right rear wheel and right side of differential. Is this a matter of running rich? What would be the most logical things to start checking. Thanks. Howie

07-21-2013, 10:40 AM	#2
pat in Santa Cruz Senior Member Join Date: May 2010 Location: santa cruz, calif Posts: 2,011	Re: Recent experience and an unrelated question sounds rich to me. You should be getting 18-20 mpg on the highway. The first thing I would check is fuel pump pressure. If its higher than 1.5 psi, the float is being over ridden by the pump. Do not rely on the regulator dial, use an accurate pressure gauge. I cannot see why you need a pump on an updraft carburetor unless you are not using the cowl fuel tank. Also, The float in the carb might be set too high or could be sinking, the main jet could be worn too large, there could be a leak from one of the jets, or your GAV could be too far open or have a leaking seat. If you're not the carburetor tech you would like to be, Berts sells some really well done rebuilt Zeniths with flow tested jets.

07-21-2013, 10:50 AM	#3
Purdy Swoft Senior Member Join Date: May 2010 Location: Alabama Posts: 8,099	Re: Recent experience and an unrelated question It very well could be that an adjusting needle seat was accidently installed in place of the compensator jet , that goes in the left rear carburetor bowl . the two parts look very similiar and have been known to get mixed up. It happened to me once over twenty years ago. After installing the correct compensator jet, the problem was solved. You can observe pictures of these parts on pages 61 and 63 of the newest Brattons catalog.

07-22-2013, 07:04 PM	#4
howie123 Senior Member Join Date: Jul 2010 Location: Eau Claire, WI Posts: 113	Re: Recent experience and an unrelated question Sponsored Links (Register now to hide all advertisements) Thanks for the input. I should have been more clear. My gas tank is behind the seat and just a little too low so it runs out of gas going up a hill. I will start checking things out one at a time. I have thought of adding a line parallel to the fuel pump and only use the pump on hills. Would it also be necessary to bypass the regulator or would the fuel run through it? Thanks again. Howie