I've got a trashed block with a good crank, and a seller with a good block and a crank with a spun rod bearing. Can I swap my good crank into the good block by just matching the journal bearing sizes, or do I need to do any machining? It may be an obvious question but I want to make sure. Thanks.

 

why wouldnt you be able to? just do what you said. take the bearing and the main caps and put them on. you should be set! but you might have to use the rods from the bad block. if they are good. if not you might have to get the crank machined.

 

Wouldn't I be able to size the rod bearings just like the journals? I've read the procedure in the helms, I'm just making sure I'm not missing any obvious problems.

 

because the wear on every bearing is totally different. and if it is a different wear the crank will not be able to turn. install it and turn it. if it turns your good if not try switching the bearings. let us know how it works out.!

 

Trust me ... you only want to do this once. Order some plastigage and new bearings. Have a machine shop measure all of the crankshaft journals. Have them measure all 8 rods and tell you which are the 4 best ones to use. Make sure you keep each rod and cap pair together.

 

I would be skeptical doing this, especially if it involved an AP1 & AP2. The Stroke length is different between years which could have you bending valves, having your timing off, etc. All depends on the combination of parts you are using between the years if at all applicable.

AP1:
Bore: 87mm
Stroke: 84mm
Compression: 11

AP2:
Bore: 87mm
Stroke: 90.7mm
Compression: 11:1

Also make sure if you are swapping parts from a good block into one with a spun bearing make sure you are changing out the oil pump.

Just something to think about.