Black diamond valves

elefantrider said:

Ok. Sounds like the way to go then, especially if used with Bronze guides.
Anyone have in stock Diamond Valves for an Atlas motor? I assume they just be can be swapped out against the plain steel valves if the valve job is still fresh, and guide to stem clearance is the same. Not sure if the special coating adds to the stem thickness vs. stock valves.

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They are fine in an Atlas head. I think some of the Atlas valves were a different length but everything else is the same as a Commando and as long as you can adjust the valve clearance with the pushrod length you have - you are fine. You have to check the clearance because all brands of valves and guides are different. I use .0015" clearance on the intake and .002" on the exhaust. Tighter can seize up.

elefantrider said:

Ok. Sounds like the way to go then, especially if used with Bronze guides.
Anyone have in stock Diamond Valves for an Atlas motor? I assume they just be can be swapped out against the plain steel valves if the valve job is still fresh, and guide to stem clearance is the same. Not sure if the special coating adds to the stem thickness vs. stock valves.

Click to expand...

You can use them in an Atlas motor if you install shorter pushrods. The Commando valves are .100 longer than the Atlas valves. Black Diamond does not make the shorter Atlas valves without a custom order.

Do not install them with tight clearances in an Atlas motor unless it uses full pressure lube to the head. They will seize do to the small amount of oil from the return line oiler.

If you convert to full pressure lube then you will also want to run valve stem seals.

The Black Diamond valves are slightly larger in stem diameter than most un-coated valves. Jim

Thanks, will probably order up a set for the Commando, and look for a set of Commando pushrods on ebay.


With the taller Commando valves, don't i need a taller shim stack or cups under the spring to make up for spring pressure?
What is the correct spring pressure on the seat?

elefantrider said:

Thanks, will probably order up a set for the Commando, and look for a set of Commando pushrods on ebay.

Makes me wonder why Rabers did not suggest this when I asked about putting them in my P11 head rebuild. Instead, these guys preferred to charge me double price for NOS Atlas valves they had laying around in their inventory. Go figure.

With the taller Commando valves, don't i need a taller shim stack or cups under the spring to make up for spring pressure?
What is the correct spring pressure on the seat?

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The valves are longer above the collet groove so the spring height remains the same.
Around 80 lbs seat pressure would be stock. Jim

jseng1 said:

Do Black diamond valve tips have the same pitting & wear problems as stock valves? Do they need lash caps as well?

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Jim,

They are all Kelly uses in the race motors he has built w/ your parts...No Issues whatsoever.

Mike