P&C measurement

Alright boys, what is the proper way to measure cylinders. I had them done here and they were good but the guy I sold them to said that they are WAY outta spec. Help me out.

Adam Roseneck

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1978 911SC 3.0
roseneck@cyberbeach.net

Adam,

Tell the guy to get a factory spec book, and read carefully on p.41! The two measurements are made at 90 degree angles, parallel to the wrist pin direction, and at right angles to that. If your cylinders had crosshatching still visible 30 mm down from the top of the cylinders, all the way around for 360 degrees, there is no way they could be out of spec!
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Warren Hall
1973 911S Targa

[This message has been edited by Early_S_Man (edited 03-30-2001).]

find the spec in the book. open up a micrometer to that spec, set up a dial bore gauge from the micrometer, set it to zero, and walk it down the bore observing how far off of zero it reads, then again at 90 degrees from where you first measured. this will tell you if it's out of round, or tapered. we like them really round, and tapered no more than .002 ( thou.). more than that and the rings may not seal, and there could be piston slap. even .002 is not really too good.

That pisses me off, there was DEFFINETLY cross hatching ALL the way down. The guy had even talked me WAY down on the price.

Now I have to find another buyer because I came up short this month (low hours at work). I even had to postpone a trip with my girlfriend because of this.

The guy said that he took it to the machine shop at a university and had it done. He said that only 2 cylinders were useable.

Wow, am I ever getting pissed off... People bother me...

Sorry, kinda cranky, I'll cool off later

Adam Roseneck

P.S. Thanks fellas!

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1978 911SC 3.0
roseneck@cyberbeach.net

As Mr. Walker points out, the proper tooling for such measurements is a necessity.
A bit of training and experience is also required to use the tooling.

I had to sneak my cyls. into work (two at a time in the lunch box) to do this. I use a Sunnen "super mic" to set bore gauges.
Jo blocks are another alternative.

If one is going to present parts as "within
spec" it would be wise to insure that they, indeed, are. This is not a job for an amateur.

I'm sure that Mr. Walker or any other
professional, with the proper tooling, would be happy to measure such items (for a price)
and supply hard data for each item.

J P Stein

I had taken them to a machine shop and they told me that they were fine. 1/1000 th of an inch and .75/1000 of an inch off. From what I was told, that was in spec.

Thats why I'm angry.

Where am I supposed to find a 'professional' here? I even drove the 300 miles to Porsche only to have the guy tell me that aslong as the crosshatching was visible, that they were fine.

Adam Roseneck

Adam Roseneck

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1978 911SC 3.0
roseneck@cyberbeach.net