Measure Bearings in Case/Rods Or Separate?

[jamesjedi]

Hi,

After reading endlessly on measuring the main and rods - I see some recommend that they do not “crush” the bearings. It will affect the bite of the bearing. They recommend measuring them separately outside of the case and measuring the case bores to determine clearance.

Any thoughts on this method?

Thanks for any help.

[ed mayo]

I'm curious how they would get a bearing clearance measurement that way. I've been "crushing" the bearings for 50 some years now, have yet to see a problem?

[Catorce]

There are a few ways to measure the bearings and the case.

As with any of these methods, you must have thoroughly cleaned the case, mains, and parting surfaces before doing any measurements, because even a bit of sealant or debris left on the mains could affect your measurements.

Also when you mate the case halves make sure the locating bushings are installed on the #1 bearing; they help case alignment. So here's your choices:

1. Measure the case bore without bearings. Bolt the case up, tighten the through bolts in the proper pattern and with the proper torque. You can leave the perimeter bolts off for this step. Then, measure each bore with a dial bore gauge. Your spec will be published in the appropriate WSM for the year of the motor. For a 3.6, the spec is 65.000-65.019mm.

This is an excellent way to measure for in spec bores and for ovality, if any.

2. Measure just the bearings themselves. This is done with a micrometer and the bearings are measured in three places, at either end, and in the middle.

3. Measure the case with bearings. Same as#1 except you insert the bearings into the case and then measure the bore again, but this time it is the crushed bearing bore. Of course those new bearings will now be crushed into their final shapes, so they now must be used in the same journals and in the same orientation when you assemble the motor. Mark them with a sharpie so you know where they go. This measurement needs to be done ONLY AFTER #1 because you need to have an in-spec main bore for this measurement to mean anything. Oh, and you need to have measured your crank journals as well so you can subtract that number and determine your bearing clearance.

4. Measure the case with the crank and bearings in place. This method uses plastigauge to determine your bearing clearances and many, many people use this method BUT you need to have done #1 first to make sure you have a good bore.

Hope that helps.

[jamesjedi]

Thank you for the replies. I appreciate the comments.

Ed - many do it as you have done.

Catorce - thank you for a great explanation.

If the bearings become committed to that saddle, you can not mix and match for better clearance.

I have the tools- what is better? Perhaps a choice that provides the same solution? Perhaps (as always) I am over thinking this.

[Neil Harvey]

Originally Posted by jamesjedi

Hi,

After reading endlessly on measuring the main and rods - I see some recommend that they do not “crush” the bearings. It will affect the bite of the bearing. They recommend measuring them separately outside of the case and measuring the case bores to determine clearance.

Any thoughts on this method?

Thanks for any help.

???????????????????????????????????

"They" should never be listened to!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[jamesjedi]

Thanks everyone. That's all I need to hear.

I will assemble case with bearings then measure. Thanks Neil.