Carburetor/choke problems

[viningben]

So after my previous post about drilling out my exhaust manifold to replace studs for my sisson choke, I finally got that work done and re-mounted my carb and choke. I adjusted the choke and set it as the manual said. The issue i am having that I hope any one can help with is.. the sisson choke closes to start the engine but as soon as engine starts the choke goes 100% open and car stalls and dies. I can start the car and hold the choke 75% closed and it will run like a dream but as soon as I let the auto choke take over the choke opens all the way and the engine dies. I have cleaned the carb, replaced fuel lines and done every thing i know how to. Can any one please lend me some advice on what I am doing wrong?

 

Ben

D24 fluid drive

Stromburg 1bbl

Sisson choke 

[P15-D24]

Did you check these on the Downloads page?

 http://p15-d24.com/files/file/33-sisson-automatic-chokepdf/  and 

http://p15-d24.com/files/file/32-sisson-choke-manualpdf/

[Plymouthy Adams]

If I am reading this correctly your choke is working right but your car refuses to idle when the engine is hot enough  to defeat the choke..sounds to me you need to go through the carb as it seems you have a primary circuit blockage...

[DonaldSmith]

There is a procedure for adjusting the linkage between the choke pot and the choke plate.  As I remember, a pin goes into the shaft of the choke pot to hold the arm in the right position when the linkage is adjusted to close the choke plate.  It's all  'splained in my service manual.  

 

While the engine is cranking, the starter solenoid energizes the choke pot, closing the choke plate partially.  The cold temperature closes it the rest of the way.  When the starter is done, the plate opens partially.   So maybe the linkage needs adjustment? 

Edited April 23, 2014 by DonaldSmith

[_shel_ny]

Was the sisson choke complete? Bi-metallic spring in the base?  Spring properly connecting to the part that moves the arm?

 

When the manifold is not hot enough to relax the bi-metallic spring it should not let the choke valve assembly in the carb open all the way.

 

Electric portion for starting.

 

Bi-metallic portion after start, and also controls the amount of closure once the warm up starts, as in when the engine is hot, the electric portion no longer completely closes the choke valve assy. in the carb all the way.

Edited April 23, 2014 by shel_ny

[viningben]

Yeah i have tried the adjusting as in the pdf's attached have goes over. and the choke does close when it goes to start. but as soon as i let off the start button the choke goes 100% open. and the car dies. 

 

Plymothy : I have cleaned as much as i could wire brush/ tooth brush and carb dip with out hurting anything. I have also pumped out most of my gas tank and changed fuel filters.

[viningben]

Yes shel-ny it is complete and looks identical to your picture.

[_shel_ny]

And you did remember to put the gasket in?

Edited April 23, 2014 by shel_ny

[viningben]

The original gasket was garbage it was worn down and tattered to pieces. so i found some exhaust gasket matl and made a new one.

[viningben]

Is it at all possible that maybe the solenoid on the auto choke is wearing out or weak? Maybe I need to replace it? They are awfully expensive and I would hate to spend a ton of money on it but, it seems this is th only thing that keeps me from taking her out on the road..

 

Ben

[_shel_ny]

Do you still have a problem when the engine has heated up? At that point the sisson choke is pretty much out of the mix, as the spring is relaxed.

[_shel_ny]

The solenoid only functions during starting when voltage is applied via the wire from the starter.

[DJ194950]

With motor cold!,  try setting the choke arm to achieve about 75% of choke closure. It should go to 100% when starting, then will drop back to the 75% closure and open slowly, but only with the throttle opened slightly because the steps on the throttle stop are rotated with the choke closure to hold the throttle open more until throttle is open more. Full open with a fully warm manifold And choke.

 

Best,

 

Doug

[_shel_ny]

With motor cold!,  try setting the choke arm to achieve about 75% of choke closure. It should go to 100% when starting, then will drop back to the 75% closure and open slowly, but only with the throttle opened slightly because the steps on the throttle stop are rotated with the choke closure to hold the throttle open more until throttle is open more. Full open with a fully warm manifold And choke.

 

Best,

 

Doug

Great suggestion. I agree. If the choke is full open before starting, is is going to be full open as soon as the engine starts.

[viningben]

Great idea.. So I got looking at it and if i leave it pinned while I i adjust the linkage i cannot do that .... but I took some needle nose pliers and rotated the pinned side of the shaft foward and pressed the arm back and it looks like it will work to keep the choke 75% open after started drop out.

 

Will test this first thing in the morning will let every one know how it comes out

 

Ben

[desoto1939]

I have the Sisson Choke testing stand that was usedd to test to make sure the choke is working properly. The stand has a thermometer on it. You put the choke inthe stand and then rotate the arm to a set position on the scale and use the metal tool that goes into the slot at the base of the choke.

 

Then you pull the pin and the choke if is is working properly will then move to indicate on the sacle if it is within a 10-15 ampunt based onthe current temperature based on the reading on the thermomter.

 

If you can not get the  unit to work and you want to send it to me I will put it on my stand to test but you need to pay for the postgae to send it both ways.

 

I also have a power point onthe sisson choke that I did for the AACA annula meeting in Phila I can send you the power point if you send me your home email.  No charge for testing the choke.

 

Rich HArtung

Desoto1939@aol.com

[desoto1939]

This stand will not work to test the sisson chokes that were used on the 49 and up Plymouths sin ce the arm is on the other side.

 

Rich HArtung

Desoto1939@aol.com

[desoto1939]

Here are pictures of the starting position on the testing stand and ending position note the pointer position on the sacle onthe metal plate.

 

Rich HArtung

desoto1939@aol.com

 

[Lumpy]

How about a manual choke? That would fix it.

 

ken.

[Dodgeb4ya]

A  picture of the sisson choke tool being used to adjust the choke blade. A drill bit that fits very accurately will do the job too. The tool must go all the way down to the slot at the base of the choke unit as already mentioned.

[desoto1939]

you can also use a number 4 drill bit  or go to a bicycle store that sell bicycle spokes. Get one that fits throught the hole with a tight fit and make you own tool and keep one inyour car and one in your tool box.  I did this before I got the original tool kit for the sisson choke.

 

Rich HArtung

Desoto1939@aol.com

[buddy123]

My ‘48 Dodge Deluxe, with a Stromberg carb is difficult to start cold.   Ok when warm.   
When cold the choke is 75 to 80 percent closed.   If I close it all the way, she leaps to a start.   
after reviewing this thread, it seems that there should be a solenoid on the choke activated by the starter that closes the choke 100 %  on cold startup
I don’t see any thing like that and no wire from the starter to the choke. 
 

The manual choke adjustment directions make no reference to a solenoid.  Although these directions to say to adjust choke until choke blade is closed tight

Any suggestions.  
 

thanks guys

 

 

 

 

 

 

[Plymouthy Adams]

the sissons choke has to be operated properly...you only get voltage to the solenoid when cranking and why it is important to depress the pedal when cranking and let up to set the choke as it will be able to overcome the stops of the choke and fully close.  If you hit the gas pedal from there while starting or between starting you will again have to depress the pedal and release during cranking to over come the stops and again set the choke closed.  Else it will default to a partial choke. 

[buddy123]

Thanks Plymouthy

 

now I understand the starting procedure, but where is the solenoid and the wire supplying voltage from The starter ?   I don’t see either one on my car

 

thanks again 

 

 

[Plymouthy Adams]

the choke body is a solenoid in and of itself that is activated by a wire from the starter motor or at the motor relay contactor.....if you do not have a wire from the starter to the little electrical solenoid on the manifold.....test to see why...this could well be damaged or just left off because the last guy did not understand how it operated.  Check the solenoid with a good VOM then test it electrically with a jumper...if all is well, set the unit up with the jumper and manually lock the position with the carb linkage....once that is confirmed....run you wire normal from the starter and go about starting your car proper procedure.  These work excellent when set up and allowed to operate by the  user....

 

ADDED NOTE......when connecting a wire the tab requires a rather short screw...you do not want to go through this tab and hit the manifold and cause a dead short...this may be why it was disconnected as the PO did not understand all of the proceedings.

Edited April 7, 2020 by Plymouthy Adams