On another thread I related a problem I was having with power and attributed it to possible carb ice. It looked like it. It smelled like it. It even walked like it. It wasn't!

Turns out it was two bad lifters on one cylinder. On one lifter the spring would not compress and on the other it would barely compress. Both were out of spec by .050.

This condition will apparently cause intermittent power problems. As I found out!

Two lifters going bad on the same cylinder ??? Ya should go play the lottery tonight, there is better odds on hitting it then to have your issue...

Skystrider wrote:On another thread I related a problem I was having with power and attributed it to possible carb ice. It looked like it. It smelled like it. It even walked like it. It wasn't!

Turns out it was two bad lifters on one cylinder. On one lifter the spring would not compress and on the other it would barely compress. Both were out of spec by .050.

This condition will apparently cause intermittent power problems. As I found out!

That makes no sense, If you were trying to compress the lifter full of oil then you should be measuring the bleed down time. If it doesnt then why? dirt carbon etc.

Are you saying that after the lifter was disassembled the spring was .050 short? Or did the last guy who put your cly on mess up on the valve geometry,
There is a spec for the rocker clearance with the lifter compressed you can change that with push rod length.
??????????????????

When the lifters were removed and empty, the spring could not be worked on one and barely movable on the other. Unlike the other lifters that were checked in a similar manner where the spring action could easily be worked by hand.

Apparently the barrels would bind inside the sleeves on occasion causing the loss of power because the valves could not fully open or close in a normal engine cycle.

When they stuck, the mag check on run up would show a 100 plus drop on one or both mags. So I would try carb heat and/or leaning the mixture. The lifters would unstick and I was left thinking I had solved the problem because the mag check was now good.

That is one reason why there is a spec, so that at bottom or top of lifter plunger travel engine will still make power.

Folks that change cylinders with no regard to retaining the setting and you end up to tight or to loose depending on plunger position.

If you want to have some real fun take all your lifters out, put the high flowing ones in the exhaust positions, and watch the cht drop
Of course you may want to get them reground before you throw them against the cam in a different location.

Since your going through this exercise you may want to check the other cylinders to make sure the geometry is right on those. If they were all done by the same guy at the same time.

mr scout wrote:Since your going through this exercise you may want to check the other cylinders to make sure the geometry is right on those. If they were all done by the same guy at the same time.

I agree with you. My mechanic and I had that discussion to make sure we didn't just stop at the first problem lifter that was found. All the lifters were taken out and checked.

The plane had just completed a thorough annual. I actually had the power loss issue flying the plane back from the field, where the annual was performed, to my field. The next day I went back and talked with the mechanic. He confirmed that the plane had been test flown before I picked it up. The pilot said that it flew great. I guess that is the nature of this particular problem. I know it is going to take me a few hours of flying to get my confidence back that it is solved!