[Fot] checking bearing clearances

[Bill Babcock]

I've always found plastigage to be more accurate than telescoping  
gauges. You get two error sources with telescoping gauges--one when  
you tweak them through the bore against the friction stopper and the  
spring (picture a little boing as the radius of the gauge slips past  
perpendicular), and the second when you read them. I only use them for  
approximate readings--I don't think you can get them to read within a  
consistent thou of an inside mike, though they are very handy for  
quick and dirty. I've had my set for forty years. YIKES!!

I wouldn't bother to buy an inside mike unless I was building more  
than a few engines a year. Measurements take practice to make  
accurately, that's what good machinist are for. Plastigage is how you  
check that nobody screwed up and you didn't swap bearing shells.

On Jan 31, 2008, at 2:28 PM, Glenn Franco wrote:

> Mark J Bradakis wrote:
>> I use plastigage, since I don't have a decent inside micrometer.
>> Maybe it would be worth it to get one that would cover the
>> appropriate size for TR6 and Spit big ends and mains.
>>
>> mjb.
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>>
> Mark
> Pick up a set of telescope gauges at your local tool supply or even at
> harbor freight.
> They expand and take up the dimension of the cylinder and you use an
> outside micrometer to take your measurement.
> They also sell small hole gauges (same principle) for measuring things
> like valve guide dimensions (id).
> I have been using them for years.
> But I always check with platigauge before assembly.
> Glenn Franco
> 72 Spit racer under construction & too many TR's
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Bill Babcock
Babcock & Jenkins
Billb at bnj.com
503.936.7660
www.bnj.com