I have a CAT 3208 block in the shop, that is used for a tractor puller. The ONLY part of this motor made by CAT is the block, and that is filled solid.
There are homemade solid aluminum heads, billet crank, custom rods, camshaft cut from 8620, etc. They run alcohol, and with three (dual)staged turbos, build up to 90 lbs of boost pressure. They run it at 6500 RPM. Quite a piece of hardware!!
The heads were designed for a rocker shaft, along with roller(?) tipped rockers. They had also made roller lifters, with larger sized 1" rollers for the camshaft.
The valve train on this motor has not held up.
My job, is to make a new valvetrain for this motor. This will include the roller lifters,with link bars, a rev kit(springs to stabilize the lifters), new rocker shaft mounts, rocker shafts, rockers, and measure for the new pushrods.
I talked to several engine parts builders, and have gotten some very helpful advice.
One current problem is the material for the rocker shafts. I want to run roller bearings in the rocker arms, on a hardened shaft.
The rocker shafts on this motor are pressurized to oil the rockers. Curiously, there is no oil gellery to the lifter bores. So the big question is, is there a source of shafting that is suitable for the roller bearings to run on?
It was also suggested that I could have shafts gound, hard chromed, and ground down to run with bronze bushings on the rockers, but that doesn't sound like like less work or expense compared to running standard roller bearings, like some of the builders do use.
Any thoughts on the shafting, or alternately, standard bearing races?
I can start another thread about all the other parts of this valvetrain, it is an interesting problem.