Big-end oil supply holes

[allan.walker]

I have an assortment of used Square Four crankshafts. Most of these have been reground in the past. My question relates to the oil supply hole in the big-end journal.

Some of my crankshafts have simple straight-drilled holes, whilst others have a 'countersink,' (for want of a better term.)

When having the worn shafts reground, should the oil hole be 'countersunk' or not?

[Bob.Murphy]

When building my Square Four (a Very long time ago) I used a "Quarter Round" file to widen the oil holes a bit. This gives a better spread of oil under the shell and was, I hear, an Ariel factory mod.

It worked well for me.

Bob.

[allan.walker]

That sounds reasonable, Bob, thanks.

[paul.jameson]

I have never "countersunk" any of the holes on my squares. There is a diagram in Waller showing how to do it but it seems relatively uncommon to me.

[allan.walker]

Thanks Paul. Perhaps it's not necessary, then.