Hello, I have a Kohler CH18 engine that was brought to me because after about 50 hours since a new cam was put in, it bent a pushrod and acted like it ran out of gas. we took it apart (i run the same engine in my pulling tractor) are re-rung it. we put it all back together, and it wouldnt run on ether. if you pull the choke, fuel blows out the top of the carburetor. we performed a leakdown on it and determined the intake valve to not be sealing correctly, because air was coming out of it. that in itself seemed odd because we had a valve job done on it too. then today while i was working on it, i replaced the head on that side and it still bent the #2 cylinder, exhaust pushrod. i have put a different head on it, different lifter in it, different valve in it, different pushrods and different rocker arms on it, i even put a new cam in it. i am at a loss and dont know what to do from here. any help?