Update to broken crank or spun bearing

[Flyingpiper59]

Good day Forum Chums ………quick update…….. I have ascertained that the knocking in the engine was a spun rod bearing…number 2… Since I have the pan down……I’m up to replace all four…Additionally….I saw a video from MTFCA….. Delineating how to replace a camshaft without taking the engine out…. I might do a 280 cam …….along with freshening up the rings…. I would like to thank everyone gave me input on my engine knock
….Cheers!….. I do have one question there seems to be a lot of side play on the journals…..even the rods that are tight to the crank….I’m flying the big scary airplane to Portland and I left my T manual at home in the barn…. Does anyone recall the specs for a side play?

[Kerry]

I don't recall that the service book gives a clearance spec on side play of the rod, back in the day you bought new rods or Ford offered a change over service for them. Anyway, the rod babbitt width is 1-1/2" same as crank. When I do rods at 1-1/2" that can give up to several thou on a good crank.

[Flyingpiper59]

Thanks Kerry that’s what I surmised…. I noticed there was a lot of room on either side of the middle main journal

[Kerry]

Yes, the block length of the center bearing is 2-1/8". Early built engines would have the cap made to the same length with a babbitt flange each end. I still do that but many rebuilders don't, some even end up with a front bearing cap in the center one which are 1-15/16" long.

[TXGOAT2]

I believe that Ford specified 1/32" side play for the small end of the rod. It is of critical importance that the rod journal on the crankshaft be in good condition.