Identifying Tillotson carb

Ordsgt

Ordsgt

Senior Member
I have not seen a Tillotson like this. I have rebuilt and installed many carbs. Zenith, Marvel, and Tillotson but not seen one with the adjustment on the bottom of the carb. This was on the car for decades and ran with it but numerous fuel leaks prompted replacement with my preferred carb a Marvel
 

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It looks like a Tillotson "X". A lot of Tilly Xs ended up on farm tractor or other engines. If this a drain, it might be protection against water in the gas on a vehicle that gets irregular use, and is frequently exposed to the weather - like a tractor.

I don't have my notes on this handy, but there was also a Tillotson "XF" - perhaps others.

Tilly X is probably my favorite carb.

Joe K
 
I think someone added that hardware store valve to drain the carb's bowl of dirty fuel and/or water. The hole's thread count and size are very common, so numerous plugs and valves could have found their way here over the years. I am sure it is not a factory-installed item. We would have seen such a carb model by now many times. A "farmer fix" that didn't work = leaking from the lowest point on the carb.
Marshall
 
I removed the needle assy and there is a jet orifice under it. So it is an actual adjustment.
It is marked as a model X
 
Come to think of it, that drain plug looks like what Model T Holley NH and Kingston carbs used on the bottom of their bowls. Installed properly, they didn't leak. But then, we're talking about tightening against metal versus pot metal. I wonder which one will distort and leak if overtightened? :)
Marshall
 
It is an adjustable main jet. Sort of like the GAV on a Zenith but not accessible when driving. Because all the fuel goes through it at cruising speed you can't shut it off like a GAV. The secret is knowing what the base setting is, how many turns open from being seated shut. I don't know myself.
 
Flathead said:
It is an adjustable main jet. Sort of like the GAV on a Zenith but not accessible when driving. Because all the fuel goes through it at cruising speed you can't shut it off like a GAV. The secret is knowing what the base setting is, how many turns open from being seated shut. I don't know myself.
Click to expand...

I agree. An after market adjustable main jet. I have seen similar on Stromberg 97s. Speedway Motors may have them. Never seen one on a Tilly before tho.
 
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The XF was a Ford replacement carb. The X was likely for other industrial purposes. A person has to remember that Tillotson and Marvel Schebler were both divisions of Borg Warner Corporation. Both made carburetors for all sorts of manufacturers as well as the public. Model A engines were a common industrial engine. They were on combine harvesters, water pumps, saw mills, generators, and air compressors to name a few. Each use may have had it's own special needs. It would be interesting to know if that model X carb has the old GAV in it or if it's plugged. It would only use the choke in that case.

The Marvel Schebler on my Ford 850 has a knob for the high speed jet needle. The instructions give a setting to start with but it's only to get the engine started and running. It takes a lot of adjustment to get the tractor to pull power properly and it can't be done on the fly. A person has to start out with getting it to run at high rpm and not stumbling through rpm changes on the throttle. After that a person has to fine tune it while pulling power. The final setting is way above the initial setting per the instruction manual.
 
I took the carb apart and checked out the passages. The gav adjustment needle is there and does operate but only in motion. The passage goes from the bottom of the bowl to the needle valve but there is no outlet to the carb. it appears to never connected. The adjustment on the bottom has a passage to the same bowl bottom port but it also connects to the venturi. As someone stated this may have been for a stationary engine or another make of car. Although it hooks right up to a model A all the GAV does is operate the choke
 
On the Tilly, Blank X or XF are all the same carb. Just sold by different suppliers. Rotowrench is correct the XF was sold by Ford, the X and blank were sold by other suppliers.
Strictly marketing hype.
 
On the Tilly, Blank, X or XF are all the same carb. Just sold by different suppliers. Rotowrench is correct the XF was sold by Ford, the X and blank were sold by other suppliers.
Strictly marketing hype.
 
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