For the first time in 40 years I’ve got a 292 that has gone through 2 thrust bearing in 500 miles. There is no interference from the transmission and the crank flange is smooth. The end play is .008 when installed and wound up .022 after 300 miles. The crank was ground.010 and clearances were fine. Anybody got a idea I’m open for suggestions.

Automatic or standard shift transmission?

Lorena, Texas (South of Waco)

Straight shift

Is the thrust flange wearing on the front or rear? if rear, do you have throwout bearing clearance, you say no transmission interfearance, but could there be a burr on the input shaft pushing the clutch disk forward, also could there be a rod that's bent a little?

I thought the same thing but I’ve had the transmission out twice and checked all of that. I’m stumped

Having more information on what vehicle this is and exactly what transmission is being used will help to pinpoint exactly why you are having main thrust bearing wear issues.
 
This sounds like an input shaft that’s simply too long.  You don’t mention if this is a car or truck but interchanging the bellhousings between the two can create some unique problems.  The truck bellhousings are deeper than the car bell housings.  Likewise, the truck transmissions have longer input shafts than car transmissions.  Also, the standard transmissions from behind a small block Ford have pilots on the end of the input shafts that are approximately 3/8” longer than what you will find on the Y-Block and FE applications.

Lorena, Texas (South of Waco)

The first all syncro 3 speed I put in a 292 back in 1964. Input shaft was too long. I put front end alighnment shims between the transmission and bellhousing to make it work. No issues with it.

Andy and I had a good phone conversation regarding his thrust bearing wear.  He does have a T5 transmission behind the Y with an adapter.  He is also using a sealed bearing for the pilot bearing in the back of the crankshaft.  The transmission does shift cleanly and gives no indication of misalignment between the input shaft and the crankshaft.  I suggested that he try a bronze bushing instead of the sealed bearing in the back of the crankshaft as the input on the T5 has no play or wibble wobble at all.  There is potentially a small amount of misalignment between the transmission and the crankshaft and with a sealed bearing at the crankshaft, it’s possible that there is some binding going on when everything heats up.  Andy will keep us posted.

Lorena, Texas (South of Waco)

Since Ted and I talked the other day I’ve pulled the sealed pilot bearing and have replaced it with a bushing. I believe the sealed bearing had to tight a tolerance to the input shaft, although it did slide smoothly it’s possible the shaft was locking to the bearing under load. I’m waiting on my new thrust bearing to show up and put the bushing to the test . Praying this is the fix . I’ll be keeping y’all posted . Thanks Ted you’re 427 story got me to thinking