Carb jet question

53Farmall

53Farmall

Member
Hello, I have a '53 that has had a complete engine rebuild (bored, pistons & rings, valve seats machined, new valves & crank ground). Compression on my cheap gauge says 125. It has an after market carb on it that runs well but I'm getting carbon on the plugs and the inside of the muffler pipe. It doesn't work very hard but is there another jet I should be using? or is this the result of not running it under load? Timing seems fine and the carb is adjusted as well as I can get it. Any thoughts?
 
What plugs/heat range are you using. Consider running a hotter plug and see if it makes any difference. Also if you can check the main jet size, the IH OEM carb was somewhere around .032. JMHO Stan
 
The ignition timing should be set using a timing light, like cars used in the past, if the Cub has a Battery Ignition unit.
A 1953 Cub probably has a Battery Ignition unit.
 
I'm running Autolite 3116 plugs and the jet is the stock size. I'm not sure if I can get another jet to fit that carb or not. It has battery ignition. I marked the distributor before I removed it then when I reinstalled it I set it by the calibrated ear then checked the original marks and they were bang on the original setting. I may have to borrow a timing light just to double check.
 
make sure the advance unit is working on the distributor,, these old units freeze up, springs break etc ...
 
The Chinese carbs that I've checked have jets that are .040. If you have the oem carb, swap jets and see if that helps. I'm not sure if the discharge tube threads are sae or metric without checking. Jet threads in the Chinese carb are the same as oem, TM sells several sizes.
 
Thanks everybody. I'll double check the jet just to be sure. I had the distributor apart to clean and inspect it. I'll have another look just in case something went wrong since.
 
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