Main bearing install tip.

[manbridge 74]

Originally Posted by m42racer

?????

That's like saying if my mother had wheels she'd be a bike!!! You are talking about two different things here.

A drill bit is for drilling a hole. Would you agree? They make special tool bits for chamfering holes, would you also agree?

I find nothing wrong with the idea just how you are doing it. And, you put it out there as a tip on a DIY forum. Maybe you know how to do this with a drill bit, but maybe "Fred Smith DIY guy" doesn't and leaves burrs and has oiling issues to the bearing.

Was hoping you would leave a foot note to use the proper tool to do this mod (tip) and make sure no burrs are left.

Would a pro do this, with a drill bit?

I think you make a good point. All DIY procedures regarding something as expensive as an engine should be vetted/approved as regards to methods by someone with experience. I'd use my extremely sharp no-one-else-can-touch Hanson bits for this without batting an eye.

Regarding bearings in general. The new idea is bearings that are purposely slightly oval when cold, becoming exactly round when heated.

[boosted79]

That's been done for decades on Detroit iron. Also chamfers on crank holes. A sharp bit works ok, a multi-flute countersink would be better. If you don't feel comfortable doing free-hand a jig can be set up on a drill press to hold the bearing and then you can set exact depth you want bevel with the stop on the drill press.

[Tippy]

m42racer, what do think will happen if you leave a burr in the oil hole?

What do you recommend, a countersink or countersink drill bit? Both have 2 flutes like a standard drill bit.

What depth? Perpendicular to hole, or at an angle to the perpendicularity of the hole?

[m42racer]

Originally Posted by Tippy

m42racer, what do think will happen if you leave a burr in the oil hole?

What do you recommend, a countersink or countersink drill bit? Both have 2 flutes like a standard drill bit.

What depth? Perpendicular to hole, or at an angle to the perpendicularity of the hole?

Doing this work needs to be done with care and some thought.

If you are using a drill bit and a bit that is sharp and new, it will have an included angle of approx 120°, just under. It has two cutting faces as well. So you will create a large major diameter at a lesser angle than a 45° countersink bit will. Some may look at that and feel it is not deep enough and keep on going until the bearing shell is compromised. The lessor of an angle will make doing this work harder as the bit will want to bite into the bearing if you are not careful. This is when the burrs will happen.

As for the burrs and rough faces of a drilled countersunk hole, have you not seen how a liquid travels through a hole like this verses one without burrs?

[manbridge 74]

There are quite a few sharp edge transitions between oil pump and eventual exits. Hand or machine chamfering every one might provide some flow optimization but I doubt it's measurable.

This is more about not deforming the bearing by pressing to hard (most people know to let the bit do the work). And not leaving a raised area on back of shell, causing a high spot to wreck crankshaft.