1979 lincoln lifter question

[Joe Werner]

i did a little bit of tinkering on my lincoln today itink i found why the motor knocks. the number 3 cylinder ehhaust valve, the rod and rocker have alot of play in it and i think it is because the lifter is worn. i took the rod and rocker and put in another cylinder and it tightend up fine so, this leads me to belive the lifter is bad. does this sound like the cause of the loud knock i hear when the motor runs?

[RocketDude]

It sounds like you have eliminated the pushrod and rocker arm,by swapping locations. That would leave either a collapsed lifter, or a flat cam lobe. You should be able to watch the amount of lobe lift. Pull the coil wire so it won't start, and turn it over. See if it is lifting the same amount as the others.

If it is determined to be a collapsed lifter, you might try taking a brass hammer and giving the pushrod end of the rocker a good "Rap"! If you have lived a good, clean life, it may free it up. It's certainly worth a try before tearing the engine apart. I've seen it work a number of times. Do it with the engine running. Could be a tiny piece of grit causing the problem. Could also be the lifter has worn a hole in the bottom, and won't hold oil, in which case, its time to off the manifold. If you have to pull the manifold, depending on mileage and condition, it would be wise to replace them all.