More Progress on the 52 Merc

RalphG

RalphG

Well-known member
Got the new "long distance" 25 litre plastic fuel tank installed in the trunk of the Merc. Should give me a little more range than the gallon just under the hood. Safer too. As of tonight it also has working dash lights. Just needed to wiggle the switch the right way. Unfortunately I could not improve on that off idle stumble that the Holley is plagued with. It will literally stall out unless I pump the gas pedal carefully. Timing adjustment made no difference so I'm suspecting the power valve now.
 

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Ralph - replacing the power valve fixed the same problem on mine . If that doesn't do it , try the accelerator pump in a different hole , if that doesn't help , then replace it . - Bernie
 
It's probably the accelerator pump, rather than the power valve. The power valve kicks in at wide open throttle. (Actually low vacuum) whereas the accelerator pump gives a straight shot of fuel directly down the carb as you open the throttle. after the car has been running, stop the motor and look directly down the carb while opening the throttle. You should see two clear squirts of fuel from the accelerator pump jets.

I am writing this with a 94 type carb in mind, not sure what you have, but the principal is the same.

Mart.
 
Mart said:
It's probably the accelerator pump, rather than the power valve. The power valve kicks in at wide open throttle. (Actually low vacuum) whereas the accelerator pump gives a straight shot of fuel directly down the carb as you open the throttle. after the car has been running, stop the motor and look directly down the carb while opening the throttle. You should see two clear squirts of fuel from the accelerator pump jets.

I am writing this with a 94 type carb in mind, not sure what you have, but the principal is the same.

Mart.
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It is the Holley 1901 which is visually quite different from the 94s. The accel pump appears to give a shot of gas on both venturis when I move the linkage yet it does not seem to be enough. I always have to give a couple of shots on the pedal even before a "hot" start so this engine seems to need a lot of gas.
Also the carb bowl seems to drain over a few days of sitting.
 

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RalphG said:
It is the Holley 1910 which is visually quite different from the 94s. The accel pump appears to give a shot of gas on both venturis when I move the linkage yet it does not seem to be enough. I always have to give a couple of shots on the pedal even before a "hot" start so this engine seems to need a lot of gas.
Also the carb bowl seems to drain over a few days of sitting.
Click to expand...
Have you in fact replaced the accelerator pump?
If the accelerator pump membrane whether it be leather or plastic is bad it will not give the full shot of fuel that is necessary.
 

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You might want to put a vacuum gage on and set it up so you can view what's happening. It sounds like an accelerator pump problem but maybe you are getting some extra air in when you open the throttle.
 
I will have to check with my brother who had the carb apart to clean. There was some discussion as to whether it needed the new accelerator pump or not and I can't recall which way we went. There was also no base gasket in the kit and although the old one looked good, I guess a leak is a possibility.
 
I'm with Mart and 51 Merc-CT. Sounds like the accelerator pump. It needs to squirt out of both jets as soon as there is movement on the accel pump. Not just when you open the throttle a lot. Look for slop in the linkage of the pump to see if the vertical pump rod moves as soon as you move the throttle slightly.

Also, the power valve set up on this carb will not let the fuel drain out like on a 94 with a ruptured power valve. Power valves are not re-produced for this carbs (all brass like in a teapot 4 barrel), however the economizer diaphragm and stem that opens the power valve, comes in the carb kits, and if bad will keep the power valve open, which I still don't think would cause you're problem.

Sal
 
I solved mine on my 53 Mercury by puting a on a 94. I will probally rebuil my old teapot and put it back on someday.
 
I agree. Get an old 3 bolt manifold and forget your problems. The old Ford carb is common commodity and rebuild kits are cheap.

I did this on an old Mercury flathead about 35 years go and it worked perfectly.

The teapot carb was an abortion. I still have one in my collections and will never let it go. Too many memories!
 
JAKEFORD said:
I agree. Get an old 3 bolt manifold and forget your problems. The old Ford carb is common commodity and rebuild kits are cheap.

I did this on an old Mercury flathead about 35 years go and it worked perfectly.

The teapot carb was an abortion. I still have one in my collections and will never let it go. Too many memories!
Click to expand...
I do have a spare manifold off a 46 Ford truck engine as well as several 94 type carburetors so I guess it is a possibility. I'm not ready give up on the old teapot yet though.
 
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