JD A Exhaust Intake Question

[JeffaH20]

We are working on a 47 JD A. We have sleeved block, done Valve job etc. Upon reassemble yesterday, I noticed that while turning the engine over the exhaust port is blowing like it should but it is also sucking air. We have not messed with the timing on the tractor (Did not remove crank or cam) Only new pistons, cylinders, valve seats, etc. I have set valve lash to fix intake slight blowing (not as bad as exhaust) I cannot fix exhaust side the by adjusting lash. The only thing I did notice is that the 2 push rods on the Left are spinning some of the time while the right 2 do not. We purchased this tractor running with only about 30psi/cylinder. This was an all fuel which I have no experience with. Maybe the its supposed to suck and blow from the exhaust. Help if you can. Why is this happening? How do I fix?

 

[Mike M]

Were the valves lapped and checked for proper seating ?
I once had one that seemed to have leaky valves that I knew shouldn't as I had personally ground and lapped the valves. All I had to do was to bang the valves closed by tapping on the stem and then they seated. I had put some assembly lube on the stems and the complete valve so as not to have it rust sitting around and that trace of lube must of let them leak.

If you remove the rocker arms and pressure up the cylinders you can test for valve leakage and if you can't get it stopped by tapping,turning,and/or pulling the valve closed tighter I'd say off with the head-again.

 

[S.Crum]

You say you had a valve job done. How were the guides? Just about everytime I've had a head done, it needed at least a few guides replaced and sometimes a few valves as well. When you put the valves in did you use assembly lube or at least STP on the stems?