I haven't looked at one of these in eons, but what about cleaning up the shaft on a centerless and re bushing the rockers?
Cost would put it out of reach for the duck tape/bubble gum crowd, but might be a solution????
Since new five stand shafts are available, seems to me the drilling deal is very viable for the folks that don't want to convert to boat rocker assembly/pushrods. Can you recommend a better way of drilling the new shafts that is feasible cost-wise??
We've seen some of the nine stand shafts that have been centerless ground and then hard-chromed back to diameter but that no doubt is very pricey process unless done in bulk...I have maybe twenty shafts that could use that right now!
As for the bushing in the rocker, that is what the "rocker rebuilders" were doing until the supply of the bushing was terminated...that replacement bushing is the kicker!
And...not only does the welded rocker bushing normally need attention, so do the hardened wear pads on the valve tip end which are pressed in. The pic attached shows a workaround that some remanners have used in the past for this...they do a radius grind (resurface) on the pad and then "shim" it and hope that lifter pre-load and pushrod length will work out!
I'll get several sample botched welded rockers to ya with various issues, and a couple of useable ones so ya can see if this is something ya might be interested in doing???
The bushing is a really thin steel shell with the bronze material bonded internally. We've looked at boring the steel bushing and inserting a bronze/oilite bushing in the ole but since the wall is so thin it just doesn't appear doable.
Again...in the past, there was plentiful supply of "remanners" that did these rocker arms as well as the shafts, but due to the "no bushing" issue they have ceased production of the IH welded rocker arm reconditioned units. About a year ago we spent much time trying to locate a supply of these items, that resulted in laying in a stock of boat conversion stuff along with a few usable welded rockers.
I still have a large quantity of welded rockers to put through a cleaning/inspection process to determine if they are usable, but I've already culled about fifty items (both intake and exhaust) that are beyond redemption. I've also visited our extremely large engine core parts supplier looking for this stuff, but they have always just scrapped the core parts in the past (no market), they are now setting the stuff aside and holding for us when they get it.