Pedestal shims

You're right about damaging the pedestals Mike, cracking WILL happen and usually just by torquing the shafts in place. When I built my first stocker engine I tried to get both lifter preload and geometry corrected using .015" shim stock and while it 'sort of' worked, it wasn't long after I noticed the tell-tale crack in the pedestal... oops! That was back when we HAD to use non-adjustable production rockers according to the NHRA rules at the time, hmm...back in the ice-age?! It didn't take me long to figure that wasn't the route to go, but the crescent-shaped shims are. Unfortunately, I no longer have access to the machine tools needed to reproduce these or I'd be making and probably selling them myself.

There's a real good article on the B3Racing page about geometry and good information as well. The sweep is one of the more important items not only for efficiency but parts longevity as well. Thanks for the heads-up fellas, much appreciate.

I used to love the tapered shims--hate we can't get them but....I have used dozens of sets of home made shims over the years--always with stamped rockers and hyd cams--I have never split a stand. I understand the math and all but they work on regular old street engines vs. ordering expensive pushrods. Yea I know about geometry but on a stamped rocker the pad is plenty big enough and correcting lifter preload vs. having the plunger down is a big big deal even on a Plain Jane.

Hughes sells them I recently bought some.

The last ones I bought from Mancini were NOT tapered.

The last time I bought shims from Hughes they were, but they'd stopped selling the .060"-thick ones and were down to only the .020" and .040", IIRC. That was years ago and I have no idea what they sell today.

Not sure if I have any of the good ones left, either unused or used. I'd switched from stacking the tapered ones to having a nice set of thicker parts machined by the late Dan Costello a few years ago, and may have pitched the rest of the shims after that.

I called and had an interesting conversation with Michael at B3racing today and that's the direction I'm going with this project as it's more than just 'a few shims'. Check out his tech article on rocker arm geometry and Jim Miller's page as they go pretty much hand-in-hand. Great info and I'm sure many Chrysler racers and builders here on moparts would benefit from this correcting their geometry as well.

www.b3racingengines.com/MoparRockerArmGeometry1.asp

www.aera.org/engine-professional/rocker-geometry/