Hi. The left side was removed from 05 twincam. The right side is the newly bought lifter. (harley 18538-99c) The oil hole position is different. Is it compatible?

 

Position of the oil hole makes no difference

 

If so, where should the oil hole position go?

 

Does not matter
Oil under pressure will flow around the small diameter section and find the hole

 

As mentioned, the oil hole location doesn't matter. And I think the one on the right is an older "B" lifter...



FWIW...

I would not put a Harley "-99C" lifter in any of my Twin Cam bikes...

Your '05 bike came OEM with the "-99B" lifters. They are considered to be one of the better lifters HD ever offered. I wouldn't hesitate to re-use a "-99B" lifter.

The "-99C" lifter became OEM in mid-2011, they are considered sub-standard as far as lifters go. Calling them "sub-standard" would be kind in the opinion of many others.

Anytime I go into a Twin Cam engine with the "-99C" lifters, they get replaced with better lifters. I put cams in a both a 2012 and a 2016 Twin Cam. One was under 5K miles and the other around 10K miles, both got new lifters and the "-99C" lifters went into the trash...

If you are in the cam chest, I would also suggest replacing your inner cam bearings. You have INA brand B-148 caged bearings as OEM. I would install the better replacement Koyo B-148 captive needle bearings. There have been several reported failures of those INA brand B-148 bearings which can lead to big $$$$$ repairs.

I would not go into the cam chest just to replace the "-99C" lifters or INA brand inner cam bearings, but consider them an excellent, inexpensive preventative maintenance step any time I go into the cam chest for any reason...

Good luck with your lifter install...

 

I saw the thread title and thought you were pledging your allegiance to twin cam motors and would never buy an M8...lol.

 

I thought you meant you were a twin cam lifer, after seeing the lifter harley is putting in the M8s.

 

As always hattitude.