Originally posted by Mark Charlton:
... What's the cost/benefit differential between stainless and regular steel ...
Everybody wants guide lines. So for folks who need benchmarks, guidelines, and limits I tell them 400 horsepower and/or a 6200 rpm rev limit. If you want to have more horsepower or a higher rev limit you'll need to spend the money on ALL the parts needed for higher rpm.
If your Panteras engine is to be rev-limited to 6200 rpm it doesn't need stainless valves. Sealed Power has 2.041/1.655 steel valves (p.n. V-2075 and p.n. V-2030) for $136 USD per set. Sealed Power has no current listing for the steel 4V intake valve, I've found steel 2.19 intake valves to be currently hard to find amongst my normal sources. The Melling V1172 listed by 4V&Proud would be a good recommendation if you can find it. But the 1.710 steel exhaust valves, Sealed Power p.n. V-1879, are available for $128 USD per set of 8.
If your Panteras engine is to be rev-limited at higher rpm it DOES need stainless valves because (1) they are lighter weight and (2) their stems are designed for tight fitting single key locks. The valves are just one set of several parts that must be upgraded to operate the engine reliably at higher rpm.
But those are only two of the reasons for choosing stainless valves. Stainless intake valves (3) are available as “Racing” valves which are equipped with valve heads which increase air flow and are lighter than standard stainless valves. If the cylinder heads are equipped with 2.04 intake valves then (4) stainless valves make it possible to substitute 2.12 diameter valves in place of the 2.04 diameter intake valves. Manley 2.125/1.655 stainless steel valves (p.n. 11344-8 and 11807-8) are $438 USD per set; Manley 2.19/1.71 stainless steel valves (p.n. 11872-8 and 11805-8) are $390 USD per set. All these prices are from Summit Racing.