In Isky tech. tips 2006 it is suggested that stainless is only higher in strength then most conventional alloys at temperatures above 800/1000 degrees. Hi-Po chevy valves may actually be stronger for typ. street engine. If you get the bottom of the line manley or whatever are you going to be worse off? any thoughts on this, are the saveings worthwhile.

So do some people still run regular chrome stem valves which are actually stronger at room temperature.? I'm not sure how much cheaper they are. here's where I got this Info. http;//www.iskycams.com/techtips.php

Whatever you use make sure to get good valvetrain support pieces such as (valve springs, lifters, pushrods, retainers and keepers) and measure everything including piston-to-valve clearance. I have a friend who built drag race motorcycle engines and he told me he never dropped a valve after going to stainless steel valves and these engines routinely ran over 14,000 RPM.

Your line of thinking is correct. If you are rebuilding a set of cylinder heads, more often than not, most of the good vavles you can buy are stainless. Its the same with aluminum heads. The material of the head doesnt have anything to do with how much air a head can move. In fact, depending on the combo a comparable iron head(as far as overall flow numbers) can definitely run better due to better thermal efficiency, but with the same flow. But, unfortunately, 90% of the really good conventional, and obtainable cylinder heads you can buy are aluminum cause it seems that aluminum heads are where the aftermarket uses all their research and development tricks. Im sure there are good conventional valves out there besides stainless, but most of the good ones with the features are usually stainless cause the aftermarket focuses on those and you pay for em(kinda like the aluminum Vs iron thing). As far as the strenght factor, you are right about that and thats why stainless valves have hardened tips. If they didnt, they would gall up real bad under average temps cause they are softer unless you run em as hot as they need to be for the stainless material to act to its full potential. Unfortunately, youd proably melt the piston tops long before your stainless valves were at their peak temp and hardness. You are correct that many conventional alloys can actually be more durable, and as long as the valve job is good and the repsective valve size coincides with the buildup, there would probably be little or no difference from one material to the other. Possibly weight differences will effect results depending on the actual amount of difference between the different alloys in quenstion. But just like cylinder heads, reguardless of the material, if the cut of the valve is right, and the valve job and anything else, the air will follow through it just the same reguardless of the actual alloy. See what Im sayin.

Originally posted by greg_moreira:
Its the same with aluminum heads. The material of the head doesnt have anything to do with how much air a head can move. In fact, depending on the combo a comparable iron head(as far as overall flow numbers) can definitely run better due to better thermal efficiency, but with the same flow. But, unfortunately, 90% of the really good conventional, and obtainable cylinder heads you can buy are aluminum cause it seems that aluminum heads are where the aftermarket uses all their research and development tricks. would it be more cost effective for the head manufacturer to cast and grind out aluminum rather than iron since aluminum is less dense? I was thinking about the cost of blades/ tool wear and tear.

Yeah probably is easier to machine plus saves a few pounds.I see WORLD uses Manley street-flo forged steel valves in their heads at least on the spec. sheet I have. Is that because their better or because their cheaper?

Tommy,

To answer you question in you Subject line we would need to know your planned combination and an idea of your useage of the motor.

But for me I have used the Manley Street Master line in many engines with very good results. I have run them in my Street Stock circle track engines @ 7200 RPM without any problems at all. For the price I think they are a great value.

airrj Just wanting to build a reliable 355 street engine. So in the summit catalog the street flo is a couple dollars more then the street master it says in the heading all manley valves are 1 pc. stainless steel I guess it must be a missprint on the world head spec. sheet I have. It says Manley Street-Flo forged steel. Or do they have another line of steel valves with the same names as the stainless.