Valve problem : intake / exhaust

[hjans]

Hi there
While inspecting the head i run into a problem.
Seems the former owner swapped the valves in one head by mistake ( or in the hurry)
The guy is dead, so........
One valve has just a slight cavity, the other is a bit deeper.
I checked with the pictures i took before dis-assembling, and they are installed the same way as before disassembly.
Thus in one head the intake and exhaust is changed.

How can i say wich is wich ??
What damage can it cause if one valve is changed with the other ?
Is it possible that the guy just changed two valves ?


Added a pic , hope it is clear to you.


Thanks

[panhead_kicker]

I can't tell you how to identify which valve belongs where. My understanding from what I have read is that exhaust and intake valves were made of different metals. The exhaust was made to withstand higher temperatures. You could run an exhaust valve in the intake, but not an intake valve in the exhaust port. It seems as I recall that the stock exhaust valve may be heavier than an intake because of the metallurgic differences.

[Cotten]

Beyond metallurgy, the only real significant difference is that exhaust valves were given more stem clearance.

For an example of common late 20th Century specs: assuming a blueprint spec of .3750" for both intake and exhaust guide bores, the intake would have a stem of ~.3735", whereas an exhaust stem would be ~.3725"

Vintage specs were enormously sloppy by comparison, but the relationship of intake to exhaust was the same.

Most often in the greater vintage American motorcycling world, an intake valve would be concave, and an exhaust would be flat or convex, but this is a rule of thumb often broken over the years.

....Cotten

[hjans]

Thanks
Will try to identify the manufacturer/type and maybe will get to know this way which is the exhaust and which the intake.
Hans

[hjans]

Here an update on my valve problem.
I first mailed to Manley, as far as i know a well known valve-manufacturer, convinced they would be able to solve my problem.
They send me a lot of info, none of wich did do it.
The only difference they told me of is the size of the valvestem, and to measure that i really did need a micrometer, my caliper just didn't do it well enough.

Then i removed the valves, identified them as Rowe valves, sended them a mail, and look .... 5 hours later the problem was solved : the intake valve disk will be attracted by a magnet, where the exhaust will NOT.

Thought you wanted to know.

Hans

[Panacea]

Did they say what the exhaust valves are made of? I've heard the term "nitrated" but never heard they were non-ferrous...Mike

[mbskeam]

stainless steel?

mbskeam

[hjans]

They didn't mention the material the valves are made of.
Take a look at their site : interesting info there !
http://www.roweusa.com/index.htm

Hans

[john HD]

looks like most of them are black melonite, whatever that is.

it is also nice to see they offer valves in 1/16 undersize. might prevent a lot of heads getting destroyed by valve seat replacements gone bad.

john