Valve stem acceptable wear

[AlfonsoR]

Hey guys,

I am in the process of purchasing an 89 coupe. However, on leakdown, cylinder #5 had 14% loss. The rest were in the 3-6% range, and three spark plugs were oily. Oh yeah and smoky start up of course.

So I agreed to buy the car based on replacement of the valve guides and a close inspection of #5 cylinder.

This was a week ago. So now, the heads have been removed and new guides installed. Machine shop says valves are fine, so they were going to re-use all the valves.

Just to make sure the shop is doing good, what is the acceptable range of wear for the valve stems?

Thanks in advance,
Alfonso.

[Porshaah]

1 thou

[cstreit]

I'd put in new valves.. They aren't that expensive...

[E Sully]

I kept the intake valves, but I replaced the exhaust valves on my '86 3.2.

[Flat6pac]

If they are in factory spec there is no reason to replace them, the new ones are only in factory spec too.
Bruce

[Steve@Rennsport]

FWIW,.....I'll reuse intake valves as long as they are within spec, but I always replace exhaust valves if they have gone more than 50K.

They really live a hard life and I've seen them fail at high mileage despite stem wear. Its simply not worth the risk, IMHO.

[AlfonsoR]

Hey guys, thanks for the responses.

My question specifically is what is the spec for acceptable wear. Porshaah says 1 mil, but I think that's a little high. I would expect something like .5 mil?

Steve@Rennsport, thanks for the recommendation on replacing the exhaust valves.

[jcge]

From the factory workshop manual (Ref No 4805.20 1965 pg E73-E75) for the 2.0

I beleive these are unchanged through to the 1989 3.2 - others please chime in if this is not the case......

Inlet valve stem = 8.97 (-0.012) mm
Clearance = 0.030-0.057mm

Exhaust valve stem = 8.95 (-0.012) mm
Clearance = 0.050-0.077mm

Regards,
John

[AlfonsoR]

Thanks John, that's exactly the type of information I was looking for.

So am I reading this right, on the inlet valve the standard size is 8.97mm and acceptable wear is up to .012mm? Wow, can't believe I guessed exactly right.

[jcge]

Correct

[AlfonsoR]

Thanks again John, I appreciate it. Now got to do some research on head studs.