Sisson Choke

[p24-1953]

I removed and cleaned my sison choke. This is the closest thing I have to an arch enemy on this car. Prior to cleaning when the lever arm was connected to the carb the unit would click but not pull the arm down more than a 1/8" if at all. If the arm was disconnected the lever would move fully if activated. I removed the unit cleaned and oiled it and reinstalled it. (it was really dirty and covered in surface rust.) Now the unit will activate the choke 50-60% of the time. It seems to be related to the temp. I have set the unit up according to the manual. This morning for example, 30 degs pressed the peddle fully once and then held at half throttle when I turned the key the choke did not close . it left a ¼” gap and the car would not start. ( I cranking for 15 secs. Then pump the peddle twice, and repeat, it took 8 tries to get it to start ). Yesterday afternoon at 50 deg. it snapped shut every time you touched the key. So could it be that my electromagnet is so week it cannot fully operate the choke? I have run a manual choke in the past, but i want this to work right.....

[Joe Flanagan]

I just disassembled and cleaned mine, too. I tested it with the battery on my daily driver and I got a good snapping sound. It's not installed because I'm still assembling the engine. There are a lot of small parts that pivot on each other. Is everything truly clean? Did you put it back together correctly? I was a little turned around at first when I went to put mine back together. As far as the electromagnet being weak and dependent on temperature, greater minds than mine will weigh in on that.

Sisson chokes come up on e-bay pretty regularly, it seems. There is a guy who goes by the name of pugrudy who sells them.

[greg g]

Are you trying to open the choke withthe throttle closed or wide open? I beleive the manual might tell you to floor the throttle before engaging the starter on cold days. this might have something to do with the choke butterfly not closing all the way. Also the act of cranking the engine might pull it closed via the air passing throught he carb. the spring contracting is what opens it as it heats up as the exhaust manifold warms.

You might want to check it operation with an assistant to hold the carb WOT and see if it closes further.

[p24-1953]

i can see the choke butterfly as i turn the key, with out the air cleaner. it doesnt matter if its half throttle of full throtel is it is cold it will not close completly

[greg g]

How close is it getting? Is there not an adjustment where the lever attaches to the butterfly pivot?? Where you ccan set the butterfly to the closed position and then adjust the mechanism to retain that position??

[desoto1939]

Send me your home address and I will send you a phtocopy.

Rich Hartung

desoto1939@aol.com

[p24-1953]

its strange when its cold it leaves a 1/4" open and will not pull shut. when the outside temp is warmer then it snaps shut. i was thinking it wouldnt matter what temp it was when i set it it should work the same.

Rich, i have a copy of the set up requirment and it is set up to the factory manual. i have a differnt top for the carb. maybe the butterfly is gumming up when cold and offering resistance.

[desoto1939]

Is there any posibility that you might have some lubriplate or lithium grease on the linkage or on the pivot for the butterfly.

Possibility that this might be causing the butterfly not to fully close when the temp is very low.

ALso check for any burs i nthe linkage and moving parts.

If setup properly then the unit should close off the butterfly

Question are you using the correct sisson choke. The early years used the one with the lever on the right sdie and the later ones used the units with the lever on the left side. Just asking.

If all else fails then I have a couple of these NOS chokes with the arm on the right. I could send you one and you can put this osnthe car and give it a try. The unit just might be worn in some place. Just athought.

rich Hartung

desoto1939@aol.co