Farmall H sucking back exhaust

It has always had a slight miss in it that I never thought anything about.

The other day it was cold and I was warming my hands above the exhaust pipe and I noticed that when it missed it would suck my unbuttoned shirt sleeve down into the muffler. I grabed a short lenght of baler twine and held it at the exhaust. It would blow it up untill it missed then it would quickly suck it down and spit it out.

Im thinking this is part of my problem. What do you think. I guessing a sticking valve or broken valve spring. That is about the only thing I can think of.

It seems to do it most at idle and under heavy pull.

Let me know what you'all think. I want to get this problem fixed I am tired of cleaning sparkplugs every couple hours.

Thanks,
farmallwayne

• Here is the previous post about not being able to lean it out.

JT has it. You are describing a classic burnt valve symptom.

Allan