Looking for 502 MPI Roller Lifter Help
 

OK, I am looking for information on the hydraulic roller lifters used in the 502 MPI engines. I have an engine with a loud tapping sound and could not identify where it was coming from using a stethoscope so I removed the starboard valve cover to check the rocker arm adjustments. Two of the lifters can easily be compressed by pushing on the push rod end of the rocker but there is no clearance when released (it feels like a light spring pressure pushing the push rod up). When I assembled the engine I adjusted these by preloading 1/2 to 3/4 turn on the lock nut. The questions are: Is it normal for these to bleed down so there is no hydraulic pressure in these lifters? Is there another preload spec for these lifters? I plan to reassemble the exhaust and upper intake tomorrow and run the engine with the valve cover off to determine if this is the source of my tapping sound and if both of the soft lifters pump up. If one of the lifters does not pump up is there any problems with adjusting the preload on the lifter with the same clearance as a sold roller lifter and running it like that so see if the tapping sound is reduced or eliminated? Thanks.

Inspector,
It is pretty normal far any hydraulic lifter to bleed down after a while when the valve is open and there is valve spring pressure on it. You could try loosening the preload to just about 1/8 turn or so. I would not run them with actual clearance like a solid roller, you risk the snap ring coming out of the lifter and causing a real mess :(

I would go through the valve adjustment before running the engine any more to see if any of them are "real" loose. You might have a roller bearing in one of the lifters coming apart. If that is the case you do not want to run it any more. If any of the rockers are "really" loose and the nuts are still tight, that is a very real possibility.

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

A stock 502 MPI (I'm assuming Gen V or VI) should have a non-adjustable valvetrain... Torque them down and go... Unless it's been modified...?

Exactly.
What does it have for rocker arms? Does it have the stock stamped steel rockers or has someone changed them out to roller rockers with the Gen VI conversion rocker studs?
Eddie

More Information on Set Up
 

Sorry, I neglected to mention that the engine has been updated with the 500 EFI Cam and Crane Gold Roller Rockers with the head stud kit. The rockers were purchased used from an OSO member with low hours (under 50) and I have only run the engine for 15 hours. Again, I plan to run the engine later today with the valve cover off to confirm the two soft lifters pump up. Is there any way to know if there is a bearing problem with a roller rocker short of removal and disassembly?

Thanks.