No, the Mityvac gauge is not an "accurate" gauge, but it is great for "ballparking" your problem area. I truly can't think of a reason to have a precise gauge for troubleshooting your vacuum system. You are basically trying to insure your system is holding a vacuum when required. I manage a calibration lab here in Houston and half of our workload is pressure related test equipment. Periodically a customer will send in a Mityvac pump and gauge for calibration. We get a kick out of it and almost feel guilty about taking their money...we let 'em know they are throwing their money away. These types of gauges are typically ±5% of reading...good ballpark gauge.

I appreciate your physics lesson. Never heard it explained quite like you did, but you sure did get your point across. Might try your approach with my new employee at work.

Mike

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Mike

'80 300D
'84 300D
'85 300D
'87 300D