The Ford Barn

Solo_909 · 03-30-2019, 11:31 AM

Quote:

Originally Posted by 51 MERC-CT

To check one source of "stumbling". The normal position for the accelerator pump adjustment is the center hole on the plate. If it is on the center hole move the pin to the outer hole or if in the inner hole move one hole outwards. (use a screwdriver to pry away and drop into hole)

It’s on the center. Just for my knowledge what exactly does switching holes do to the acelerator pump?

Also why would it stumble only until I drive it hard and getting into higher RPMs and then clear up?

rotorwrench · 03-30-2019, 11:46 AM

The photo shows an example of the dash pot mechanism used on Merc-O-Matics so it's a bit different than the manual transmission cars but not by much. The adjustment for the accelerator pump is a stroke distance adjustment. One way is more stroke and the other is less. You may also have a problem with the power valve vacuum actuator situated in the shroud housing of the carburetor. The vacuum is fed to it through a long circuit that can leak if the shroud fit is off or a gasket is leaking.

Solo_909 · 03-30-2019, 12:05 PM

Okay so I warmed up the car this morning and the choke plate does open slightly but...... when pressing on the throttle the choke step linkage never moves so when pressing on the throttle the idle doesn’t drop down. It also seems to run really rich with the jets only open 1/4 turn out. The choke plate does open when it’s warm but only maybe about 1/4” open. See photos first photo is of the car warmed up.

51 MERC-CT · 03-30-2019, 12:54 PM

Based on your picture of the carb., it appears to have a'49 to early '50 carburetor installed with the choke up on the carb.
'50 and '51 had a divorced choke that mounts on the intake manifold.
It would be interesting to see if the hot air source is in fact hooked up to the correct intake manifold.
If the choke did not have a hot air source, the choke would not open.

Solo_909 · 03-30-2019, 01:09 PM

Quote:

Originally Posted by 51 MERC-CT

Based on your picture of the carb., it appears to have a'49 to early '50 carburetor installed with the choke up on the carb.
'50 and '51 had a divorced choke that mounts on the intake manifold.
It would be interesting to see if the hot air source is in fact hooked up to the correct intake manifold.
If the choke did not have a hot air source, the choke would not open.

So it does have the correct intake for the choke tube and it does connect to the choke housing. I do need to take the tube off and see if it’s clogged up though.

51 MERC-CT · 03-30-2019, 01:38 PM

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Quote:

Originally Posted by Solo_909

It’s on the center. Just for my knowledge what exactly does switching holes do to the acelerator pump?

Also why would it stumble only until I drive it hard and getting into higher RPMs and then clear up?

It gives a little richer shot of fuel to compensate for the added air volume until a higher RPM is reached and a different fuel circuit takes over. {at least as I understand it )

Solo_909 · 03-30-2019, 06:48 PM

Gotcha,

So I’m sending the carb back to the guy who rebuilt it. Something just isn’t right with it. I set it maybe like 3 different times however the stumble wouldn’t go away. Plus once the car was warmed up when I would press on the gas pedal the idle would get higher not lower. Also when adjusting the choke plate using the black knob cover I had to turn it counter clockwise to shut the plate which is the opposite of lean.

I pulled the heat tube out and it seems clean and clear with no carbon build up so it wasn’t that.

rotorwrench · 03-30-2019, 06:53 PM

Both my early 1951 cars have that type of carb. The date code is on top of the accelerator pump hump up on the air shroud. The divorced type came in later 1951 after the first of the year.

There are two tubes for the choke heat. One runs from the carb base down to the manifold and the other runs from the manifold back up to the thermostat chamber. It sounds like the thermostatic spring is not engaging the choke shaft or it's just not getting hot enough. A bad thermostatic spring may also be a cause. It's hard to say when you can't look at it.

richard crow · 03-31-2019, 10:30 AM

there is such a thing called a choke pull off it,s a device that pulls against the choke butter fly by vacuum. is yours working

rotorwrench · 03-31-2019, 12:27 PM

That's the little piston in the choke stove thermostatic chamber.

Solo_909 · 03-31-2019, 09:53 PM

Quote:

Originally Posted by richard crow

there is such a thing called a choke pull off it,s a device that pulls against the choke butter fly by vacuum. is yours working

No idea, I’m sending it back to the rebuilder so he can take a look at it.

03-30-2019, 11:46 AM	#22
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,440	Re: 1951 mercury carburetor choke adjustment The photo shows an example of the dash pot mechanism used on Merc-O-Matics so it's a bit different than the manual transmission cars but not by much. The adjustment for the accelerator pump is a stroke distance adjustment. One way is more stroke and the other is less. You may also have a problem with the power valve vacuum actuator situated in the shroud housing of the carburetor. The vacuum is fed to it through a long circuit that can leak if the shroud fit is off or a gasket is leaking.

03-30-2019, 12:54 PM	#24
51 MERC-CT Senior Member Join Date: May 2010 Location: East Hartford, Ct Posts: 5,898	Re: 1951 mercury carburetor choke adjustment Based on your picture of the carb., it appears to have a'49 to early '50 carburetor installed with the choke up on the carb. '50 and '51 had a divorced choke that mounts on the intake manifold. It would be interesting to see if the hot air source is in fact hooked up to the correct intake manifold. If the choke did not have a hot air source, the choke would not open. __________________ DON'T RECALL DOING SOMETHING FOR MYSELF BASED ON SOMEONE ELSE'S LIKES OR DISLIKES

03-30-2019, 06:48 PM	#27
Solo_909 Senior Member Join Date: Oct 2016 Location: NorCal East Bay Posts: 409	Re: 1951 mercury carburetor choke adjustment Gotcha, So I’m sending the carb back to the guy who rebuilt it. Something just isn’t right with it. I set it maybe like 3 different times however the stumble wouldn’t go away. Plus once the car was warmed up when I would press on the gas pedal the idle would get higher not lower. Also when adjusting the choke plate using the black knob cover I had to turn it counter clockwise to shut the plate which is the opposite of lean. I pulled the heat tube out and it seems clean and clear with no carbon build up so it wasn’t that. Last edited by Solo_909; 03-30-2019 at 07:04 PM.

03-30-2019, 06:53 PM	#28
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,440	Re: 1951 mercury carburetor choke adjustment Both my early 1951 cars have that type of carb. The date code is on top of the accelerator pump hump up on the air shroud. The divorced type came in later 1951 after the first of the year. There are two tubes for the choke heat. One runs from the carb base down to the manifold and the other runs from the manifold back up to the thermostat chamber. It sounds like the thermostatic spring is not engaging the choke shaft or it's just not getting hot enough. A bad thermostatic spring may also be a cause. It's hard to say when you can't look at it. Last edited by rotorwrench; 03-30-2019 at 07:13 PM.

03-31-2019, 10:30 AM	#29
richard crow Senior Member Join Date: May 2010 Posts: 1,770	Re: 1951 mercury carburetor choke adjustment there is such a thing called a choke pull off it,s a device that pulls against the choke butter fly by vacuum. is yours working

03-31-2019, 12:27 PM	#30
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,440	Re: 1951 mercury carburetor choke adjustment That's the little piston in the choke stove thermostatic chamber.