Hey guys

Well, I have been a member at MTF for awhile and have a problem. I have a 1966 suburban 12 with an HH120. It has the problem of surging at low RPMs. But runs fine in under a load. And it will even out with half choke. I should mention, it has a kohler float in it (I am cheap). I made it work. But I am stumped. The smoke from the engine looks white. Not blue as if it where oil. But its losing oil. Any ideas?

When did the surging start? Before or after the float replacement? Surging is a sign of lean running. The engine will go into a lean cycle, causing the governor to go into a open throttle position. When that gives the engine the required fuel through a open throttle, it speeds up. When RPM's slow, the cycle begins again.

Rule out the float issue first. Drain and refill the tank with fresh gasoline. Current mixtures of additives in our gasoline don't work particularly well with our old machines. Plus I have noticed the gas doesn't last as long.

Also, don't overlook the possiblity that it is just a slow speed adjustment that needs to be made on the carb.

White smoke (steam) from an auto engine means an antifreeze leak into the combustion chamber. Of course the Tecumseh is air cooled. Do a compression or leak-down test on your engine to establish the condition of the rings and valves.

I worked on an old Tecumseh once that seemed to be smoking white. It turned out that there was a ton of combustion byproducts in the cylinder head. The motor had been run slow all it's life. Some of the crud would come out the exhaust every time I hit the gas. I removed the head and cleaned out all kinds of junk....problem solved.

Will do spence, I will check the head tonight (hoping to god I dont rip the head gasket). The surging started before the float.

You might also want to check the gasket between the carb and the head. If the engine is sucking air into the chamber, it could act like it is running lean.

White smoke in an air cooled engine sounds scary, tho.

Good luck.