[433lemans]

I'm wondering if these TRW replacement valves are considered a "one piece" or a "two piece" valve. I see on here that factory Pontiac valves are/were "two piece" and subject to breaking? How are they constructed to make them "two piece"?

[b-man]

The heads are friction welded to the stems.

If they’re not stainless aftermarket they’re 2-piece stock replacements.

[77 TRASHCAN]

You can tell on some valves, where the stem meets the head, that area feels and looks bumpy. Just doesn't look machined, if friction welded...

[Schurkey]

The ones you REALLY have to watch out for are the 3-piece valves.

A ring of hard steel alloy for the valve face, around a soft-steel head, welded to the stem.

I've got a BBC exhaust valve that's been blown-through where the hard ring that the valve face is ground-on meets the softer valve head.

[steve25]

A S2638 is a standard length 1.770” high comp exh valve as can be seen in my shot from a TRW catalog, and yes it’s a welded head valve.

I have used these valves for Street and flat out race usage, but I would not use them a long with the open spring pressures needed for solid roller cams , you would want a non welded head valve for pressures over 380 psi.

[Half-Inch Stud]

3-piece ring-seat valve sounds INCONCEIVEBLE. Photos though..

I noticed that PMD Ram AIR IV, or maybe some other valves had a (non-)magnetic rocker Tip on a (non-)magnetic stem, thus 3-piece.

[Skip Fix]

I have some RAIV heads with older 80s SpeedPro V-1826 intake valves listed as "8645' material but that is not in their description list in the catalog. exhausts are V3923 listed as 21-2N a stainless valve. But both are under the OE replacement sections. Flat D port vales flowed better than the tuliped RAIV SI brand/Childs Albert packaged available at the time, just used with a HFT.

I know Fererra is vague about using their 5000 series SS with roller cam pressures. They also make some of the valves for Edelbrock but say they are to Edelbrock's specs and will not divulge how they compare to 5000 or 6000 series.

[hurryinhoosier62]

Originally Posted by Half-Inch Stud

3-piece ring-seat valve sounds INCONCEIVEBLE. Photos though..

I noticed that PMD Ram AIR IV, or maybe some other valves had a (non-)magnetic rocker Tip on a (non-)magnetic stem, thus 3-piece.

That is fairly common. The manufacturers place a stellite tip to counter valve tip wear. I have several old aircraft recip engine valves that have the same thing.