Re: lifter bores

I think that it is fantastic that you have ran your engine for that many years with no problems. I happen to have the Murphy's Law syndrome in my shop so I am not so fortunate.

In my experience I found that the lifter bore diameter is a controlled leak and is directly proportional to the volume of oil that is being pumped, the leak rate of which is not enough to control the oil flow even with up to .002" clearance. The oil will flow in the path of least resistance which in this case will be up the pushrod to the top of the engine. This is enhanced by the oil holes in the lifters themselves which in my experience with both Comp and Crower rollers were 3/32" diameter both into and out of the lifters. (You wouldn't believe how much oil will flow through a hole that size!! A simpler fix would be to have lifters with the exit oil hole of .040 but just try to talk one of the cam companies into something that wasn't their idea, HAH!! You can't afford to have them custom made either) Add a HV oil pump and it gets even worse!! No drain hole or restricted pushrod can thwart that much oil flow!!!

The lifter bushings however, restrict the oil TO the lifters and thereby control how much oil is SUPPLIED to them. The rate of flow which LEAVES the lifters is now significantly reduced and the problem solved. Once you cut down the amount of oil to the lifters, the oil pump doesn't need to have the volume it once did as the leak rate to the top of the engine is significantly reduced to where the stock pump will be more than able to handle the job. I worked on this for about 10 years on and off until I finally solved it last year at this time. I took my engine apart, installed the bushings and reassembled it and it now has steady oil pressure with normal oil flow to the top of the engine, in fact I can run the engine with the valve covers off for the very first time without hosing down the walls with oil.

I would like to reiterate that I know that there are those out there that have run their engines for years with no problems and I applaud you, but unfortunately there are the rest of us....... well it seems that everything I do is the hard way.ZZ