Trouble In The Teapot

[RalphG]

The Holley teapot on my 52 Merc. It has a real dead spot off idle on acceleration. It will stall every time unless I pump the gas pedal several times. I've tried all three accelerator pump hole settings with little or no difference. Higher rpms it seems to get all the fuel it needs though. I do notice that it seems to drain the float bowl if it sits for long.
Had a guy take it apart and clean up earlier this year with all new gaskets but I'm thinking it needs to come apart again. Something stuck in the idle circuit? Bad power valve? I hate to open these up as the top float bowl gasket is so thin and easily broken.

[tubman]

Are these carbs similar to the ones found on '52-'53 Mercs? If so, a friend had the exact same problem with his '53 Merc earlier this summer. He solved it by replacing the accelerator pump itself. Also, if the power valves are like the ones used on Ford carburetors, you may have a problem with ill-fitting later model power valves. I have mentioned several times on here that I do a "leak-down" test on every carb I rebuild. I fill the float bowl with gas, and set the top on the carb. If the float bowl is empty the next day, there is a problem with the power valve, gasket, or maybe the carb body itself. If these carburetors are altogether different beasts, please forget everything I'v said here.

[scicala]

The teapot carbs on '52 and '53 Mercs are very similar in design to the later teapot 4 barrels (minus the rear barrels). The power valve is all brass and is operated by a small diaphragm and stem from above that contacts the brass power valve in the bowl. When the diaphragm goes bad, it will not cause fuel to leave the bowl. They are also hard to blow out from a backfire because of how they are mounted.

RalphG, your hesitation/stall could be because the accel pump linkage is sloppy and not really moving the pump rod as soon as you move the throttle. Could also be a missing or mis-placed check valve in the pump circuit. To check the operation, make sure there is fuel in the bowl and as soon as you move the throttle slightly, you should see the squirters shoot fuel. Also should be easy to see how far you have to open the throttle before the actual vertical pump rod moves down.

Sal

[RalphG]

Originally Posted by tubman

Are these carbs similar to the ones found on '52-'53 Mercs? If so, a friend had the exact same problem with his '53 Merc earlier this summer. He solved it by replacing the accelerator pump itself. Also, if the power valves are like the ones used on Ford carburetors, you may have a problem with ill-fitting later model power valves. I have mentioned several times on here that I do a "leak-down" test on every carb I rebuild. I fill the float bowl with gas, and set the top on the carb. If the float bowl is empty the next day, there is a problem with the power valve, gasket, or maybe the carb body itself. If these carburetors are altogether different beasts, please forget everything I'v said here.

Yes, mine is the typical Mercury carburetor also known as the Holley 1901.
The accelerator pump appears to give a good shot of gas on both sides when I view it with the air cleaner off but still the engine will die if I try to take off at anything more than gentle throttle pressure.

[rotorwrench]

My old 51 Merc with the Holley 885 has the shroud over the top and the vacuum circuit for the power valve has it's passages in there. I'm not sure how the later Merc carb's power valve circuit is routed but it has to be sealed tight for the system to work correctly. No power valve action will definitely cause it to stumble on rapid acceleration.

[RalphG]

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Originally Posted by scicala

RalphG, your hesitation/stall could be because the accel pump linkage is sloppy and not really moving the pump rod as soon as you move the throttle. Could also be a missing or mis-placed check valve in the pump circuit. To check the operation, make sure there is fuel in the bowl and as soon as you move the throttle slightly, you should see the squirters shoot fuel. Also should be easy to see how far you have to open the throttle before the actual vertical pump rod moves down.

Sal

I will check that tomorrow Sal.
Video of it's performance back in June can be viewed here.
https://www.youtube.com/watch?v=T4PHy1vhNGM

[38 coupe]

Try checking your timing. I built a carburetor for a friends 53 Mercury and it had similar problems to yours. I chased carburetor adjustments but nothing helped. I put a timing light on it and found his ignition timing was advanced way too far.

[RalphG]

Originally Posted by 38 coupe

Try checking your timing. I built a carburetor for a friends 53 Mercury and it had similar problems to yours. I chased carburetor adjustments but nothing helped. I put a timing light on it and found his ignition timing was advanced way too far.

I have an old six volt timing light I got at an auction sale years ago and have never even tried it to see if it works. Always just timed the engines "by ear" with fairly good results. We did try a little adjusting the timing and point gap on this Mercury but only succeeded in making it harder starting. It is pretty hard to adjust this one while idling now with that huge tractor battery blocking easy access to the distributor.
Just to refresh my memory, how does one connect the timing light on the 52 Merc engine?

[51 MERC-CT]

Originally Posted by RalphG

I have an old six volt timing light I got at an auction sale years ago and have never even tried it to see if it works.
Just to refresh my memory, how does one connect the timing light on the 52 Merc engine?

If you have a 12 volt light you can use it by connecting to a stand alone battery.
Most are connected to the battery for power and to #1 plug or wire for signal.
As far as the carb. is concerned, a new accelerator pump and check fuel level in the float chamber.

[38 coupe]

I static time the 8BA motors. With the ignition off turn the crank until the bump on your crank pulley is just before the pointer on the timing cover. Loosen the distributor hold down bolt and take the distributor cap off. Turn the ignition on. Back off the distributor timing a lot. Slowly advance the distributor. When you hear the points open, stop moving the distributor and tighten it down. I usually get to do the back off and slowly advance moves a few times until I am sure I have the distributor in the right spot. Tighten the distributor hold down bolt without letting the distributor move.

Note: this only works with points. I tried this with a Pertronix once and got terrible results.

[RalphG]

Originally Posted by 38 coupe

I static time the 8BA motors. With the ignition off turn the crank until the bump on your crank pulley is just before the pointer on the timing cover. Loosen the distributor hold down bolt and take the distributor cap off. Turn the ignition on. Back off the distributor timing a lot. Slowly advance the distributor. When you hear the points open, stop moving the distributor and tighten it down. I usually get to do the back off and slowly advance moves a few times until I am sure I have the distributor in the right spot. Tighten the distributor hold down bolt without letting the distributor move.

Note: this only works with points. I tried this with a Pertronix once and got terrible results.

Thanks for the detailed explanation. I did find the vintage timing light yesterday. Got it cleaned up a little but did not get to actually connect it up to the car and try it out.

[bssmnbll]

what is the float supposed to be set at on the 885?? I just put a kit in my 50 merc carb, and it had a Daytona needle valve. My "factory lincoln/merc book" does not address the float level in the carbs

[51 MERC-CT]

The 885 'back-draft' fuel level is 1/2" ± 1/32" to top of body.
The '52-'53 'teapot' may be different.

[Bob Greenwall]

I have an unforgettable "teapot" Holly story; on a 55 Merc. Part of the choke linkage came loose and the engine swallowed it...on the parking lot of Sears at Irving Park and Pulaski in Chicago as I recall. Being 20 yrs old and fearless, I bought a Craftsman tool set, along with a torque wrench; pulled the head and got the piece out. Started it up...and there was another piece lurking in the manifold! Came back the third day, pulled a head again. Wrote a letter to Ford Motor Company about that carb. I must have had a gaurdian angel. Bet his name was Henry. (Still have and use the tools 50 yrs later)

[1949f1]

Have the exact same problem with mine. A friend of mine who usually does my carb rebuilds on my cars said it may be the stroke on the pump is too short.

[scicala]

Originally Posted by 51 MERC-CT

The 885 'back-draft' float level is 1/2" ± 1/32" to top of body.
The '52-'53 'teapot' may be different.

According to my old Holley manual, the float level of the Holley 885 model carbs for '49 thru '51 Mercury's was not 1/2". The FUEL level is 1/2" below the top edge of the bowl (gasket surface). The FLOAT level is 7/32" below the gasket surface at the toe of the float with float all the way up.

Sal

[51 MERC-CT]

Originally Posted by scicala

According to my old Holley manual, the float level of the Holley 885 model carbs for '49 thru '51 Mercury's was not 1/2". The FUEL level is 1/2" below the top edge of the bowl (gasket surface). The FLOAT level is 7/32" below the gasket surface at the toe of the float with float all the way up.

Sal

As stated 100% correct. Must of had 'float' on the brain.