[ryan68bug]

I'm having issues getting my freshly rebuild H35 Tecumseh to idle. I rebuilt the engine top to bottom, including the carburetor, but no matter what I do, including ensure the governor is properly adjusted, it doesn't want to idle. The carb also doesn't seem to respond to mixture adjustments. Any suggestions, or is it perhaps just time for a new carburetor? There don't seem to be any vacuum leaks, though I haven't ruled it out.

Thanks in advance...

 

[30yearTech]

The low speed or idle circuit is most likely the problem. There is probably some restriction in it some where.

Remove the carburetor and disassemble, then with the low speed adjustment screw removed, spray some carburetor cleaner into it. It should exit out near the bottom of the nozzle area where the high speed or bowl nut screws in. There is a tiny hole drilled in to supply fuel to the low speed circuit. You can locate it by looking around the outside of the tube there is a small bb pressed into the hole on the outside where the orifice was drilled. Also check the bowl nut as there is a small orifice drilled in it to feed the low speed circuit too.

Good Luck....

 

[ryan68bug]

How quickly should the cleaner drain? It seemed it took a couple of squirts to the point where it was spilling out of the low speed mixture screw's port and then began slowly dripping out through the bottom, in the location you mentioned. I did check the oriface in the nut, and it is clear as a bell. I'm thinking the idle circuit may be blocked as you suggested, and am wondering how much pressurized air it will take to blow it clean, if that's the case?

 

[30yearTech]

It should spray out in a stream when you are spraying cleaner in through the low speed adjustment screw hole, you can use compressed air to help clear out any obstruction.