Tillotson Carb Help Needed
 

Good evening. My Tillotson carb has a leak that appears to be caused by siphoning. Yes, the gas shut off valve leaks-by slightly, but that's another story. The carb has been rebuilt, and the car runs well. The leak has been going on for a few years.

This evening I discovered an unusual amount of gas in the drip cup that I place under the carb and found the upper surfaces of the carb wet with fuel. I removed the lower half and the fuel level was OK (actually low - about 3/4 inch below the gasket line.) I noticed that the surface of the lower half was wet for about 1/8 inch around the hole for air flow to the high speed jet. This wetness, the OK fuel level and the wet fuel on the upper surfaces are prompting me to think that some kind of siphoning is going on.

Any thoughts would be appreciated. I have Moller's book for reference, but it does not explain the air flow path to this hole.

Mike

Re: Tillotson Carb Help Needed
 

the thicker gaskets may help + the ball float valve my help also . if it is the actaul valve , change it ...................

Re: Tillotson Carb Help Needed
 

Mike make sure there is a small fibre washer between the treaded end of yjr float valve and the top of thr casting when you tighten in. no washer installed nice leak, gas flows rite thru.
Have a Great Day
Gord. B by the bay

Re: Tillotson Carb Help Needed
 

I know that the original jets of the zenith were "cupped" on the top to prevent siphoning. Were the jets on the Tilly shaped the same?

Re: Tillotson Carb Help Needed
 

it sounds like a needle and seat leak. The fuel level in the bowl when removed would be low because the float displaces the fuel when the bowl is installed and would make the bowl over flow. I hope I worded this correctly.

Re: Tillotson Carb Help Needed
 

Really the only way to make sure of the amount of fuel you're getting to the chamber is to measure the float height, should 1" from top of float[or bottom depending on how you're looking at it] to the base.. Check the float arm for the wear mark from the float/needle valve, if there is a little worn dimple then gently sand/emory it smooth.. What float valve is in this thing?? I happen to prefer the Grose style..

Re: Tillotson Carb Help Needed
 

Mike;

I am currently running a Tillotson on my 30 Coupe and had a lot of trouble with it leaking. I think that the gas will run all over the pot metal making it hard to determine where the leak actually is. I changes the valve and put in a Grosse valve, sanded the one flat area where the carb separates on a wheet of glass to flatten it, etc, etc, and it still leaked. Finally I did the unthinkable and double gaskedted it where the two halves meet. Leak gone.

However, I always shut the gas off at the tank when I am stopped for more than a few minutes.

Having said all of that the car does run very nicely with the Tillotson carb.

Dick