K321 Rebuild

[AlexR 2,283]

So I went over to my neighbors today (because he has a cylinder bore gauge and micrometers) to check out the spare engine I have that I thought was a 12hp K301 because of the tins. So the bore gauge you set to the spec you are aiming for with a micrometer so I set it to the max wear limit for the K301 3.378 well it was too small for the bore by a lot well I measure the bore and it's about 3.5 it's a K321 block. So I set it for the max wear limit on that 3.503 and it's all within spec on out of round and taper and within the wear limit. So it will just need honed. 

I was feeling pretty good and starting measuring the crank. And that was bad, I am kinda curious if you guys have seen numbers this bad. 

 

X axis              Y axis

1.4871             1.4880

1.4869             1.4888

1.4869             1.4889

 

It's crazy that the taper is within spec at .0009 but the out of round is .002 the limit on that is .0005 and yes I double and triple checked you can actually see the gap going from the Y axis to the X 

It's also worn beyond the wear limit of 1.4990

Edited 3 hours ago by AlexR

[markseven 66]

My crankshaft was bad I think 

The measurement was 1.487 .

I was going to get it machined and go .020 under but luckily found a used one  that measured 1.5001.

[Achto 30,090]

1 hour ago, AlexR said:

I am kinda curious if you guys have seen numbers this bad.

 

 I have had engines with a good bore & a crank out of wack. Also had them the other way around. Explanation unknown. I would scuff the cylinder, have the crank turned down for an under sized rod & slap ' er together.

[ri702bill 10,444]

... Purchase the connecting rod first. That way the machine shop can turn the crank to match that bore for the proper clearance fit... All replacement parts have dimensional tolerances too...