I have a stock 1991 FLT with stock cam. Recently replaced lifters and cam bearing with OEM Harley parts. New 20 over Harley pistons/rings and valve job. Bottom of cylinder heads were decked with minimum cut for seal of head gaskets. Reused stock Harley non adjustable pushrods. No unusual valve train noise before I did work on motor. I know the non adjustable pushrods were installed in correct holes. Motor runs great and has regular valve train noise until 2,700 rpm. Tapping noise starts always at 2,700 rpm and goes away when I let off throttle. Not exhaust leak, I have checked. Sounds like valve noise which gets faster with increased rpm. This noise did not start until I installed new parts about 1,000 miles ago. Any ideas before I start tearing it back down this winter. Difficult to hold stethoscope on motor at 70 mph and have been scared to rev to 2700-3000 rpm in neutral in garage to locate noise. Thanks!!

 

Cut them bitches and put adjustables...

 

You mentioned you replaced the lifters. Did you mic the opening in the lifter blocks to determine if you needed oversized lifters. Went through that issue on my Shovel. Did the top end, put it all back together and ended up with the tapping noise. Ended up using Jims +5 and having lifter blocks honed to specs for the +5 lifters. Just about 2500 miles on the top end now and the valve train is as quiet as a sewing machine.

 

I did not mike the lifter holes, but the lifters seemed a snug fit. I will check when I remove pushrods. I have through about trying new pushrods, but maybe new S&S non adjustable pushrods. This motor is completely stock and I like the non adjustable. Could my old non adjustable pushrods with 70,000 miles have a reason they could cause the tapping noise only above 2,700 rpm. I checked them and they were straight, just wondered if they start to flex due to age at higher rpm. Thanks.

 

it could be a number of things did you check your deck height when you installed the pistons. they could be tapping the head. when you had the cylinders bored did they use torque plates. if not you could have piston rattle. the oil pump could be weak not keeping the lifters primed at high rpm. excessive wear on rocker bushings and the list goes on. or could just be a defective lifter. when im putting a motor together I double check all the tolerances and write them down. never assume the machine shop did it right always check there work.

 

My oil pressure gauge shows good oil pressure. It makes noise at 2,700 rpm and up when relatively cold with higher than typical cool oil pressure. When I take this apart, I am going to pull the new lifters. Is there a way to tell if a lifter is weak while out of motor. These are new Harley B lifters.

 

first you need to locate the noise is it both cylinders or just one front or back
is it coming from the top of the motor or bottom

 

Man, sorry for your pain...sounds like you did things right to get your motor back up to snuff and this noise come out of no where.

Try to determine which cylinder is making the noise. You could always move the lifters from one cylinder to the other and see if the noise moves. Might help you find the culprit.

Sorry for your pain, I am interested in what you find. YD

 

What was the piston/wall fitment?
If I remember correctly, .0008"-.0015" on those, as per stated by the Moco.
We adhere to those dimensions here when performing that work.
If the new Evo lifter from HD is also manufactured in Mexico like the new T/C "C" lifter, then that could also be a source, and as already mentioned, a good adjustable pushrod to establish the proper pre-load.
We use S&S lifters here in ALL our engine building, when needed.
Scott

 

ADjustable rods seems like the least invasive surgery to me also Doctor Scott.