Valve Guide Replacement

[LUFTMAN]

most machine shops can replace valve guides but i suggest you have them install the valve guide split sleeve inserts. they require less work and you do not remove the orignal valve guide. you drill old valve guide to a insert size and install insert then ream it to proper valve stem clearence and it takes far less material to cut valve seat plus it is still on its original center and the insert is far more superior than any replacement guide for wear. no cracked guide boss to worry about. contact dave coleman in west virgina by summit point raceway he has been repairing and racing porsches for 35+years a real grass roots racer with a no frills shop he has beaten a many of porsche high dollar racer he just does what works and you do not pay for a fancy name or shop. he does not try to reinvent the wheel. and is very afforable and resonable

[DG624]

"I would do both a cranking compression test and a cylinder leak test."

Grady,

What is a good number for both of these tests...and what is the original number?

[DanielDudley]

I would at least switch to Castrol High Mileage 20/50, if not Valvoline VR1 or Brad Penn.

[Grady Clay]

Originally Posted by DG624

"I would do both a cranking compression test and a cylinder leak test."

Grady,

What is a good number for both of these tests...and what is the original number?

There are lots of things that affect the measurements: equipment, technique, altitude, temperature and more.

Higher compression numbers are better.
Lower cylinder leak numbers are better.
Close grouping of the measurements is best.

Whatever they are, you have a ‘baseline’ to compare future measurements against.

Best,
Grady

[Rodsrsr]

For me it was obvious. All cylinders had 150 psi with the exception of #6 which had only 90. A leak down on 6 revealed 60% loss from an exhaust valve. Fresh new valve job with all new valves and my motors back to 1 to 2% leak down on all cylinders. An initial loss in power is what lead me to start investigating.