Tillotson and GAV setting

johnbuckley

johnbuckley

Well-known member
When cold I have to turn the gav about 5 full turns to get engine started. It's a Tillotson X . Once warmed up it can be closed down 4 to 4.5 turns to just one or onehalf open and then runs sweetly at that setting. Is this normal, or a sign that the float is too low, is the gav housing is worn or what?
 
John: I have exactly the same problem with my Tillotson. Post if you are able to diagnose this particular problem. I will do the same if I can locate the problem. I may not get to this immediately since I am currently running a Zenith but would like to have the Tilly available as a spare or maybe run it since it seemed to run fine when warm but was difficult to start when cold.

Mr. Texas: Thanks for your comment. I plan to check fuel flow to the main jet to see if it is restricted.

Best regards, Roland
 
Always reassuring to know that someone somewhere has come across the same problem! Carb absolutley clean and all passage clear. Fuel level is at 3/8th inch below gasket line as recommended byPaul Moller's book. Runs excellent when egine warmed up so I don't think I'll mess with it until sure of cause!
 
Something isn't quite right.. Have you had the carburetor apart ? Cleaning the passages with a spray cleaner like Sea-Foam's Deep -Creep and compressed air should clean things up.. If you can't get the cleaner or air thru all the passages then the plugs may need removal for more cleaning.. I think your float level is right, it should be 15/16" or 1" when apart.. I'm also wondering if you have a vacuum leak, the mounting flanges are know for warping and removal of the throttle plate will allow the flange to be filed flat.. Check to make sure the throttle shaft /bushings aren't binding when the carburetor is bolted back on..
 
John Buckley: I removed the new metering jet from the rebuild kit in the bottom of the fuel bowl and compared it with an old jet I had on hand. I found the new jet to be smaller so I replaced the new jet with the larger jet. This cleared up the problem and the carb now performs normally. GAV 1 turn open to start and 1/4 turn to run properly after warm up. I hope this helps with your problem.

I don't know what the proper size for this jet should be. Can anybody comment on this? As best I can measure the old jet appears to be about .040" My calcs show the new jet to be about 25% smaller in area.

Regards, Roland
 
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