VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 Carb identification?? What did it go to

Here one for you old experts. When I first got my 31 coupe it had the wrong carb on it. Since then I have gotten the correct Carter and thanks to you all its running great.
I would like to identify what this old carb original went on? It seemed to work fine on my chevy, it just wasn't correct.
here the info on the carb.


Tillotson
model JR5A


Any ideas.....

Shocks

Hi Shocks,
The TILLOTSON JR-5A carby was an aftermarket replacement model to suit all updraught Chev's from 1929 to 1931.
They were made in various models to suit alot of cars,which in effect made them a sort of universal replacement carb for your old one.
I'm running a JR-1A carb on my '28 Chev Truck,as I found it to be much more efficient than the old Carter,and made the motor more responsive.

I agree with the response. My JR5 ran well but I always had trouble with a good consistant idle.
Do you know where I can pick up some more information on carb. I wonder what the difference is between the two model numbers.

Thanks for the come back

Hi Shock's,
The TILLOTSON "JR" series of carby's were a good source for a carb that would run better than a worn out original one.
There are a few differences,the main one's being the venturi size,which is either cast on the outside of the carb,or is cast on the underside of the top half of the carb,which will be visible after you remove the float.
Most "JR" 1,1A,3,5A carbs had either a 7/8" or 15/16" venturi.The "JR" 2A which had the cast iron top body,and diecast lower body,has a venturi size of between 15/16" to 1".If the venturi size is too large for the engine,it will run fine at high speeds,but run rough at idle,as the larger venturi admits too much air.
Other factors that affect the idle of these carbs are,float height set incorrectly,float travel set incorrectly,the idle feed tube could possibly be swapped from another "JR" carb(all use the same threaded tube,different jet hole at top end)and possibly the main jet has been swapped from another "JR" carb.Another factor which will affect the performance of these carbs is that where the main jet seats in the lower half of the carb,there is a fibre gasket which fits over the end of the main jet.(Worn throttle shaft bushes will also affect idle as well.The original ones are steel(removable),and I replaced mine with hard nylon ones,which saves wear on the shaft).
If this gasket does not seal properly,the engine will draw excessive fuel past this seat,and give a rough idle due to over richness.I've found that by replacing the red fibre gasket with an "O" ring,the seal is as perfect as it can be made,and this solves any more trouble,as the diecast can distort over the years,and the soft "O" ring makes up for any deformities in the diecast.
A real good source of informatin would be the carburettor book put out by "A.L.DYKE".It's full of information on various carbs,and has a section the "JR" series carbs.I also have some other book's with information on these carbs.If you're interested,I could possibly photocopy the info for you,and send it to you.
I,myself,wouldn't put my original CARTER carb back on my '28 truck,as it goes so much better,and I get really good fuel economy.
Hope this helps you out in some way.If you'd like to contact me directly,my email address is:

wizardsmith278@optusnet.com.au

The OEM Carter 150-S carburetor for 1929-31 is a dynamite little carburetor, and it is preferred by many over the aftermarket replacement Tillotson.

The Carters (before the mid 1930's) were not "state-of-the-art" technology (Chevrolet had state-of-the-art earlier with the Zeniths used on the 4 cylinders in the mid teen, but the Carters were less expensive). A properly working Carter will certainly run the engine decently (although not so well as a period Zenith or Stromberg).

On the other hand, the Tillotson JR series was sold through mail order houses (Walmart would probably sell them if Walmart sold carburetors) to customers too frugal to purchase a repair kit for the original Chevrolet carb. That's right, a new Tillotson carburetor complete sold for less than a repair kit.

With no disrespect meant to anyone; I cannot fathom any Tillotson running better than a Carter in decent condition. If the Tillotson runs better, then the Carter needs help (maybe talk to the "junkyard dog" who rebuilds Carters when he is not adding to his record post total ).

During this period, there were many aftermarket companies producing carburetors. Some of these were decent. Some, well, best said that what they sold resembled a carburetor.

Some of the aftermarket companies in this era which produced carburetors for the Chevrolet: Air Friction, Johnson, Juhacz, Rayfield, Schebler, Simmons (decent), Swan, Tillotson, Winfield.

As mentioned above, both Stromberg and Zenith made excellent replacements.

Tillotson did sell some O.E. carburetors, primarily to the Willys company.

During the early 1930's, the Borg-Warner conglomerate acquired several carburetor companies, among them Johnson, Tillotson, Rayfield, Schebler, and Marvel.

Jon.