Starting a very interesting build for a customer...

[Jerry Clayton]

You might want to consider a larger stem sodium filled exhaust valve---that skinny stem doesn't have a lot of material with that hollow stem and of course not much strength when hot( over 1000 degrees)

[undy]

Most are going to stainless with no loss in RPM capabilities.

[Jerry Clayton]

Your talking about rpm or breaking off of the valve head???

[undy]

Originally Posted by Jerry Clayton

Your talking about rpm or breaking off of the valve head???

Both, the stainless valve is much less prone to breakage and a good quality light weight valve like Ferra's offerings won't decrease the engine's abilty to spool quickly, attain design max RPM and over stress the springs @ 7K.

[Jerry Clayton]

The stainless valve is not less prone to breakage just cause it is stainless---there are one piece, 2 piece and 3 piece valves----there has always been a big flap about one piece valves while in reality most are 3 piece----head spun welded to stem and a hardened tip--a one piece is very expensive as it is formed out of a big piece of bar stock or a very complicated forging process to make the head big on the end of a small diameter rod---

The sodium filled, hollow stem valves transfer the heat better to the guide so the head actually stays cooler and won't burn as bad. Going to say a 11/32 hollow stem/sodium filled with the necked down pro flow type head probably would be a better choice for a high heat engine.

Of course injecting some wator methonal mix thru the cylinder on the overlap could cool the head and valves-----

[blykins]

Quick update...

Ran into a little snag with the new Comp camshaft. The journals were .0008-.0009" over factory spec for an LS cam and it had .0015" runout on the center journal. Long story short, it wouldn't go in the block. (Yes, I eliminated the possibility of a bad cam bearing install by sliding a stock cam in....it went in as smooth as silk.)

Comp is making right on it....but it put a temporary pause in the mock up.