Snowblower has a Tecumseh engine, model OHSK120. It is about 20 years old and I have owned for about 10 years. It always starts, but it always has a little spitting sound when running. Getting it ready this year and it definitely seems to run rougher when first engaging the drive or auger. But if I close the choke a little it runs better, but the spitting is present. I tore apart the Tecumseh carb, reassembled and it still ran the same spitting way. I then adjusted the fuel jet screw and it ran better. The problem is that once I remove the screwdriver from the fuel jet, it will vibrate and most likely fall out of the carburetor. This fuel jet originally had what is called an "idle restrictor screw cap", that I removed to try to fix this problem many years ago with no luck. I just turned the fuel jet in until it bottomed out, so it would not vibrate out. Attached are pics of the parts list (#20 is the fuel jet) and a pic of the fuel jet. The fuel jet part number is 640016. This fuel jet has the same threads as a #8 machine nut, the length under the head is 5/8", with about half the length are the threads. Do I need some type of spring to put on the fuel jet so it will not move/vibrate while the engine is running? How do I determine what spring to order?
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That is not adjustable, it is screwed in until seated and snugged up. If you have a problem after that, the carburetor body has a blocked cross air bleed passage.
ILENGINE
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If the air bleed passage is clogged it causes a rich run issue not lean. So from the prior OP post that is ran better with the air bleed jet loose confirms it is a fuel passage issue. Loosening the air bleed and causing the engine to run better has always been a test recommended by Tecumseh as a diagnostic tool for carb issues.
And reaming the air bleed jet size will cause the engine to run leaner not richer for the people that are thinking about enlarging the jet size.