flywheel lapping

[JonE]

I have a flywheel with teeth which has never been near the 1935, 1 5/16" engine I intend to use it on.
I'm aware of the issues of flywheels getting too far down the crankshaft if you are a bit *too eager with matching the mating surfaces.
Are there any measurements I should be aware of to assess whether firstly the flywheel is OK... and how should I proceed to ensure that I don't enter the above (*) camp! TIA...

[Charles P]

I have a flywheel with teeth which has never been near the 1935, 1 5/16" engine I intend to use it on.
I'm aware of the issues of flywheels getting too far down the crankshaft if you are a bit *too eager with matching the mating surfaces.
Are there any measurements I should be aware of to assess whether firstly the flywheel is OK... and how should I proceed to ensure that I don't enter the above (*) camp! TIA...

In the vice:
Lap it to what it needs to fit properly.
Fit the rear main bearing assembly 
Fit the flywheel and torque it in. Note down the torque setting for repeatability.
Check for clearance with a feeler gauge. If there isn't any you'll need to shave a few thou off the rear boss of the flywheel.
Rinse and repeat until you have clearance.

[JonE]

ok, thanks. So the limiting factor is entirely whether it actually pulls down onto its taper (rather than getting stuck on the boss), much as per checking about the key not being too tall in the keyway?
I had wondered if there was something to do with the clutch side too.

[leaf200]

You will need enough clearance to fit the thrower

[Alan]

You need to be careful not to introduce swash into the flywheel so do a DTI check, and that the taper doesn’t protrude beyond the flywheel face so you can’t tighten it up.

[JonE]

looked up swash flywheel and it didn't even come up on Google...!
I presume that's something to do with being off centre, but how WOULD you introduce swash whilst lapping?

[Charles P]

By letting your lapping pressure favour one quadrant of the flywheel

[JonE]

understood. thanks.
Is Engineers blue going to be useful for this?

[Bob Culver]

Check with blue first. Note that later flywheels were releived in the middle, so any clearance in the middle is better not eliminated.  If any error is mainly in the flywheel may be able to initially sort on a scrap crank

[Charles P]

understood. thanks.
Is Engineers blue going to be useful for this?

Do 30 seconds with fine valve grinding paste, take it apart, clean it and then blue it. I wouldn't bother blueing first. Odds on the tea leaves would be very difficult to read.