Technical Bearing clearance for a ford flatty v8

Hey Guys, I'm kinda new this so please bear with me. I'm in the middle of building a 81T 221in flathead V8. I need to know the correct way to check rod bearing clearance for the floating bearings in this eng. I used plastigauge on the outer bearing surface and got a reading of .001. the book says I should have .0015 to .0035. I've read online that I should MIC the outer dia. of the crank journal, the inner dia. of the rod torqued to specs. get the difference. MIC the rod bearing and subtract that from the difference to get the clearance. I don't have any good micrometers, just the one I bought from harbor freight. Any advise would be appreciated. Thanks!

 

There is a great explanation in Ron Hollerans book "Nostalgia". If you don't have it, see if you can borrow one. I can't remember who, but someone on the Fordbarn was selling them. Great book.

 

Need a good micrometer to do this.

 

• Try a PM to 4tford on the Fordbarn, he was selling Ol Rons book.

 

There are a bunch of articles on the old interweb for this process. I chose one to show you.I just typed in measuring bearing clearance and got a lot of choices.

http://www.mahle-aftermarket.com/c1...5ad100ac1257a79006f8720/$file/cl77-1-205r.pdf

 

I know someone will disagree with me, but the bearings (full floaters) seem to fit the contours of the rod best if they measure 2.22 across the bearing shell at its widest point.The controversy seems to come when changing this measurement on the bearing if it DOES NOT measure 2.22. To widen the measurement,lay the bearing on a flat surface and "gently" strike it on its backside to widen; to narrow the measurement,,lay the bearing on end squarely with the surface,and "gently" strike the bearing causing the measurement to narrow. The actual desired measurement is 2.215 to 2.225 with 2.22 being in the middle.

 

OK I think I understand what you saying. Is The measurement taken from the inner bearing surface Or outer? And if my rod journals are .030 under, my measurement should read 2.252. correct?

 

OK I think I understand what you saying. Is The measurement taken from the inner bearing surface Or outer? And if my rod journals are .030 under, my measurement should read 2.252. correct?

 

The measurement is taken from the outer surface, so as long as your rod ID is standard the outside measurement should be the same even for undersize bearings. I just got done building one of these engines and I used 2.218 for the measurement. Mount the rod to the crank with the bearings in place without the piston, torque to spec and make sure the rod rotates freely.

 

Ok thanks Flatjack.