3.2 verse 3.0 Crank & Rods

[bluemoney]

I am on a bummer and have a problem. I spun #5 rod in 1994 SHO 3.2 ATX. Going to rebuild and cannot find main bearings. I can polish the crank and the old but good mains I took out of my spare 3.0 1990 SHO MTX, if I cannot get new ones, then have the rods turned on that crank. Also the rod may not be able to be resized. Please help if you can. The crank from my 3.0 is like new and am thinking about putting it in the 3.2 block, any problem? I don't know if these are internal or externally balanced as I would need to use the flex plate instead of the clutch flywheel. Also am thinking about using all the rods from the 3.0 in the 3.2. They are the same length but the crank end is made different than the 3.2, the 3.0 have a large balancing tab. I know I cannot mix and match the rods but maybe keep all 3.0 crank and rods together. Would that be a problem? Also I noticed that the piston pin end of the rod has a different size pin diameter. I haven't checked yet but I think the hole in the rod is the same on both but the bushing has a different I.D. if that is the case I think I could get new 3.2 size bushings installed in the rods. Thanks Larry

 

[sperold]

Confirm that the rod can be resized (a standard machine shop activity). Then confirm that your existing crank can be polished and that will return it to workable condition. Usually, you do not need new mains, but you say you have a good used set anyways.

My first instinct would be to work with the existing 3.2. I think when you are considering balance in an engine, it involves crank, rod and piston weight, not just crank and rods.

I have no idea on whether the internals of the 3.0 can be swapped for a 3.2, but it sounds expensive to even try.
If you can believe the advertisment, you can buy a new 3.0 crank, complete with rod and main bearings for $160.00 after you have returned a core, so take that for what it is worth. I also notice that in the 3.2 series of engines, there is no crank deal like for the 3.0, so that suggests something is different.
I have no solutions, but I hope the information helps.

 

[rbruso]

IIRC, the crank is the same between the 3.0 and 3.2. The difference is in the small end of the rod. The wristpins on the 3.2 are smaller diameter, so 3.0 rods won't work with 3.2 pistons.

You could look for a good condition 3.2 rod and cap and reassemble with your 3.0 crank and new rod bearings, reusing all six of your current 3.2 pistons. For that to work, though, you'd need to pull at least one head as there's no way you're getting a piston in from the bottom of the block. Not sure if you'd need to rebalance with one new rod, though.

 

[AREA 91]

3.0 pistons and rods have a 21mm wrist pin on the small end.
3.2 pistons and rods have a 22 mm wrist pin.

 

[rubydist]

And, yes the cranks are identical.

The rotating assembly is internally balanced, so you should take the rotating assembly to a shop to have it re-balanced once you find a replacement rod.