The V8 Owners Forum -

I had the journals of my 4.6 crank machined to fit a 3.9 block. The work was carried out by a reputable engine remanufacturer.
When i offer the crank into the block onto the new bearings, the crank will not rotate. I discovered however that if i remove the centre thrust bearing and refit the crank, it will then rotate freely.
Has there been a mistake in the machining? It appears that the thrust bearing is binding on the radius of the crank journal or is there another explanation that i may be missing?
I dont think it is a problem with the bearings as they are new clevite77's.

If that's all that's causing the binding can you not just chamfer the bearing?

with performance bearings like Clevite you have to fit the thrust bearings to the crank, had to do this with my chevy ones. You need a flat surface, piece of glass (an old mirror is very good), piece of surface plate or similar and a piece of 280 or 320 grit wet and dry paper. Check the clearance for the crank in the manual and using a figure 8 motion take the thrust bearingd down to size on the wet and dry paper. Take it slowly and fit and measure frequently, use a micromiter to make sure you take the bearings down evenly and a feeler gauge to check the clearance. it is a straightforward job but take it slowly, move your fingers into different positions on the bearings as you go so you don't get low spots.
Mike

sorry just re read your post and hairbears comment and he is right chamfer the edges, if they still bind do what I said!!
Mike

thanks guys. i wasnt sure if it was acceptable to wet 'n' dry the new thrust bearing but i suppose it makes sense. i'll be careful just to take a bit off the radius and not touch the bearing-to-journal surface...

Don't forget to tap the crank forwards and finally rearwards to settle it in the correct position. Have you tried torquing the caps down and then checking for rotation? The engine was originally line bored with the caps in situ. Also, I use a feeler guage to check thrust bearing clearance. Obviously you have the bearing settled correctly into the block locating groove.

ok. I ended up taking the crank back out and tried spinning the thrust bearing on the journal - it wouldnt. The plain shells would, but not the thrust bearing. I had a word with the machine shop and they reckon they need to open out the radius on the crank journals a little. The crank goes in on wednesday and this time i'll give them the thrust bearing with it and i wont be taking it back until i see that bearing spinning nicely round the journal. I'll let you know how i get on....

^ sounds like a solution:)

sorry boosted. ive just realized i kinda missed your first reply...
yeah the bearing was located correctly into the block and i made sure the crank had settled into place but the bu**er nipped up tight. thats why i decided just to take the crank back out. it was only when i did this that i found out that the bearing wouldnt even spin round the journal when the crank was out - let alone in the block..
in hindsight given the crank had been machined i should have checked that before i offered the crank into the new bearings/block....
oh well, at least it should be sorted tomorrow.

Update. Bottom end all sorted now. Took the crank (with thrust bearing) to the machine shop and he sorted it for me then and there. Opened out the journal radius a touch and that sorted it. Crank spins nice and free now with the mains all torqued up...
On with the remainder of the build.