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Tillotson JR-1 Carb


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Hey all, 


I've been working on my 1928 Plymouth Model Q and it has this Tillotson JR-1 carb on it. I know it isn't the original, but was planning on keeping it, unless I can't get it to run right with it. I've been able to get it running, but have to feather the pedal to keep it running. Anyhow.. I took the carb off, to tear it down and clean it. When I got the car I was told it was just rebuilt. Well, that isn't quite accurate.  I got into it and it was way dirty. So, been cleaning it and disassembling it and found the Accelerator Pump is in ROUGH shape. See attached Pics. Anyone know where I can source a new one or what I could effectively replace the "sealing surface" with? All the rebuild kits I find for these carbs don't have anything to replace or fix the Accelerator Pump. Any help would be appreciated.. 



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You are seeing the entire pump, the "sealing surface" is the largest diameter brass cylinder. THERE IS NO LEATHER SKIRT!


The damaged piece on the bottom is simply a brass washer holding the pump together.


(1) remove the washer

(2) glass bead the pump 

(3) fabricate a new brass washer

(4) peen the end of the shaft over the new washer


These units were sold through such sites as Whitney, Warshawsky, and Western Auto to customers too frugal to purchase a gasket set for the original carburetor.


According to the Tillotson books, even Tillotson did not offer a rebuilding kit.


Tillotson did offer individual parts, but they had to be special ordered. The pump is Tillotson 0-3900.


As far as the kits containing pumps, we started hand-cutting kits some 30 years ago. To date, you are the first requesting a pump. The cost of fabricating a new pump would exceed the value of the carburetor.


These carbs do have one redeeming feature: the top casting is cast iron. So one can place the top casting in a machine, and cut the flange from the rest of the casting just above the throttle shaft. One can then weld two of these together to fabricate a carburetor adapter.



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Thank you for your help, so cut off the old washer on the bottom and then install a new one and peen the shaft over? Great. Thank you for your help. 


So do I keep this carb or go with a new carb? If a new carb, which would You suggest going for the 1928 Plymouth? 





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  • 1 month later...

Hello Dwells,  I just rebuilt two Tillotson JR5 carburetors and they use the same accelerator pump as you show in your photos.  I was starting to wonder who would need such a carburetor?  and just imagine my surprise when your link showed up.  anyway,  if you are interested please send me a message.  Kenny Model A Club President Whittier California.  text 5 six 2 ate one 8 79 for nine  thank you

JR5 pic_7.png

JR5A pic-4.png

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