Measuring cylinders/pistons/crank journals/etc

[Cevan]

I'm trying to determine how I will get these measured, given the precision required.

The spec in the service manual for the cylinders is 95.014-95.021mm. The pistons are 94.979-94.989mm. Crank journals are similarly precise. .001mm is .00004" That's 40 millionths! I would think changes in ambient air temps would throw off these measurements.

Given I will likely only use them once, I'm hesitant to buy a bore gauge and micrometer capable of measuring down to this degree, as they appear to be extremely expensive. Not sure if I'm better off bringing them to a machine shop.

Maybe a stupid question but does your average machine shop typically measure this precisely? I'm sending my heads to Anchor Atlantic and haven't looked yet for a local shop to do the inspection, polishing the crank, conrods, etc.

[tocobill]

Any machine shop should be able to measure for you. I would find one that specializes in race builds as they are likely used to closer tolerances. This is even more important as they do this every day vs you buying the tools and winging it in the name of saving a buck. Buying the tools to measure with a decent precision are going to be expensive as you stated. I would print out the pages from the workshop manual if you have them so they know where to measure if not porsche specific, but again it's not hard.

[Zuffenwerker]

It doesn’t take extremely expensive equipment to measure the the skirt clearance and crankshaft. Metric mikes are great but you can use inch mikes and indicators no problem. The inch stuff is actually nicer sometimes because they commonly have graduations in "tenths" (.0001”) which is more precise than a metric mike or indicator which will have graduations of .01mm (4 tenths).

If your measuring down to one tenth Your doing better than a lot of guys out there rebuilding engine.

Like I said it doesn’t have to be as accurate as your thinking. When you measure your going to be in the range given above which is a pretty big range on a mike or indicator. If your under it will be pretty clear.

You can probably buy what you need for $300 if your resourceful but you have to know how to use the tools. If you’ve never used a mike or zeroed a bore gauge then your probably not going to be very accurate your first few tries.

[prschmn]

Check the work on your heads-I've had to redo a couple sets for another shop that they didn't get quite right. Something slipping there it seems.

[Cevan]

Originally Posted by prschmn

Check the work on your heads-I've had to redo a couple sets for another shop that they didn't get quite right. Something slipping there it seems.

Is there a shop on the east coast you'd recommend over Anchor Atlantic?

[tocobill]

Originally Posted by prschmn

Check the work on your heads-I've had to redo a couple sets for another shop that they didn't get quite right. Something slipping there it seems.

I would be curious to hear more about this. This would be the first thing I’ve heard negative about Anchor Atlantic. Bob did a set of heads for me years ago and the work was superb. Hate to see a good shop have unsolicited negativity thrown its way unless warranted.

[prschmn]

I'm not wanting to bash anyone. Just saying that I've had another shop send me heads to redo
after having Anchor do them. I couldn't say I've as many as Bob but have been doing them for many years.

[Dpmulvan]

Originally Posted by Cevan

I'm trying to determine how I will get these measured, given the precision required.

The spec in the service manual for the cylinders is 95.014-95.021mm. The pistons are 94.979-94.989mm. Crank journals are similarly precise. .001mm is .00004" That's 40 millionths! I would think changes in ambient air temps would throw off these measurements.

Given I will likely only use them once, I'm hesitant to buy a bore gauge and micrometer capable of measuring down to this degree, as they appear to be extremely expensive. Not sure if I'm better off bringing them to a machine shop.

Maybe a stupid question but does your average machine shop typically measure this precisely? I'm sending my heads to Anchor Atlantic and haven't looked yet for a local shop to do the inspection, polishing the crank, conrods, etc.

You don’t have to buy the most expensive tools to take these measurements. You can buy a set of old school bore gauges for next to nothing. You can buy a cheap dial bore gauge throw out the dial indicator and put in a halfway decent one. China has done a good job of ripping off all the quality instruments, will they last? Probably not but good enough for what you need. Or buy used on eBay

[boyt911sc]

Originally Posted by Cevan

Is there a shop on the east coast you'd recommend over Anchor Atlantic?

As long as Bob Hirst is healthy and working, I will keep sending my cylinder heads to him. Last time I spoke to him, he was fine and doing well. Once you see Bob’s work, you won’t even think of going to another shop.

Before I switched to Anchor Atlantic, I was very satisfied with my previous machine shop in PA. But kept reading how people were so happy and satisfied with Anchor Atlantic. So I tried for curiosity Bob’s shop. That was many years ago and never regretted my decision.

Two (2) shops I prefer are Bob Hirst’s (NJ) and Craig Garrett’s (MI).

Tony

[onboost]

I've seen some of exotech's work and wouldn't hesitate to use them either, as several well-known builders do..

[Cevan]

I’ve been in touch with Exotech. I would much rather drive the parts somewhere rather than ship them.