Morning All, my buddy (Buick guy) is getting rapid increasing crank end play on his 455. Build spec is .003-.009, his was .006 but after not many miles, less than 500, it’s up to .015. His forums not being much help, hoping some of you engine aces can chime in with a possible cause/solution. Not aware of any such issue with our Mopars. It’s a 70’ GS 4 speed car.

4 speed car , everytime he pushes in the clutch it forces the crank into the thrust bearing, either the crank surface is going away or the bearing is going away. If he didn't set the thrust bearing correctly when first torquing that main cap this could be a possible reason the clearance has grown , which would say he has an issue that he didn't see during assembly.

Another question is how many RPM is he turning it? Much over 5500 and Buicks will eat the mains. A stock 455 block is about as strong as wet spaghetti.

Its not going to fix itself, pull it and then the pan.... pretty simple.

All of this is correct. Crank install process needs to be correct...but

10 thou in 500 miles is a big bunch. I would be looking at something pushing the crank forward in the block. Input shaft bottomed in the back of the crank or the pilot. Guy ride around with his foot on the clutch pedal. Something.

I would drop the pan, pull the bearing and verify where the wear is. Front, rear, both. and go from there. Get the trans out and look.

Thanks for the replys. Experienced driver, no foot on clutch, not beating on it, street car no racing, input shaft was checked, Will confirm crank install procedure, he has a number of engine builds under his belt. Another local Buick guy mentioned teflon bearings may help but I think that may just be a coating, doesn’t sound like a permanent solution.

I've seen guys just stuff cranks in blocks and get lucky with adequate thrust clearance but all it takes is once without adequate clearance and bye bye thrust bearing. I had a SBC in my shop once...had 800 mi on fresh "rebuild" and the thrust was gone. Put it back together, this time checking/setting thrust and never saw it again. The little details matter.