Pulled the engine and Mr. Duggar and I, tore into the transmission. We found that the rear main bearing had 30 thousands end play. What is too much?
Yes, too much. A new main cap will fix that. However, it needs to be fitted, AND it will be nearly impossible to fit properly if the crankshaft thrust faces are heavily grooved, as most are... The cap has to be narrowed so much to pass over the high spots on the thrust faces, that when in place, it now falls into the wear grooves and you're just as loose as you were before.
I have used the shim that goes behind the crank pulley to close the end play and make the magneto work as a temporary measure pending a full engine rebuild. Temporary as in 5 years. I actually wore one out and had to install a second one in one of my cars before I finally tore it down and did it right.
I had it running before pulling the engine out to address a transmission issue. It ran smooth with very little noise. I check the rod caps and they had no shims but plastigauged at .002. The only engine issue is the end play.
Val, are the shims your talking about available thru one of the parts suppliers?
Langs has 'em:
Good luck with your project, Bill
When the car is in high the clutch spring wants to push the flywheel/crankshaft to the front when in low/reverse/neutral it wants to pull it back. Much of the wear would be on the rear thrust surface.(see *)
Adding one of those above things is going to close up the gap on the magneto because you are now pulling the flywheel/crank shaft forward closer to the mag coil ring.
Don't forget, if the pulley is not rock solid, it's going to be moving back and forth because it is now acting as a thrust surface.
*What was said above about the wear/cupped area on the crankshaft flange, this is sometimes overlooked on a rebuild. Unless the crank is new most of them are worn/cupped in the area the bearing thrust rides against. It needs to be as smooth as the crankshaft. Any roughness or ridges is going to act like sand paper and wear the rear thrust. As it is, Ford only put thrust on the cap. It should have been at on both the cap and block.
I used to place a few bronze washers on the crank but that required removing the pulley. Now that the parts suppliers have the shim available that does not require removing the pulley I use that because it is so much easier. Langs has them and I find that they last for a years touring or more.