I have an 18.5 intek engine in my tractor. I have a good spark, seems to have good compression and is getting fuel. The valves appear to be adjusted properly without any excessive looseness or tightness. It looks like there is compression coming back out the intake. The engine has low hours, but will not fire even with ether sprayed into the intake, and with the kill wire disconnected from the coils.I also took the muffler off just in case it was clogger. Any help would be greatly appreciated

Hi,
The most common problem with the Intek engine is the seating of the valve train, and requiring adjustment sometimes with low hours. It is the exhaust that usually is way off and will caused spit-back in the intake since the intake charge cannot be fully ingested because the exhaust leaves fuel/air mix still in the combution chamber. See the venerable YouTube video at:
Lawn Mower Repair Valve Adjustment - YouTube (http://www.youtube.com/watch?v=NjzX-PUjKmo)
Peace,
Clarke

Thanks for the reply. It turns out someone worked on the engine before me and had the camshaft timing almost 180 degrees off. Reset it and the valves and it runs perfect now. Wouldve been nice if the previous owner had told me that he'd had someone else try to fix it before selling it to me!