Pushrod oiling/heat?

The problems with shims more than about 0.010" thick is that for there to be no leakage, they need to be an elliptical shape, [ thinner on the ends, thicker in the middle ] to close up the gap under the shaft. That is why the pedestals crack when parallel shims get used: the ends of the pedestals are getting 'spread' & then spreading as the bolt tightens & tries to seat the shaft in the pedestal.
I did it a better way. I made my own 0.020" shims, which I siliconed to the pedestal & left overnight to cure; so this stops the oil leakage from that gap. I do not use bolts. I use s/steel studs, loctited into the pedestal. A nut is then used to 'snug' the shaft down into the pedestal; another nut is then used to lock against the first nut to prevent loosening.