Stainless steel valves

[Hotboat]

What are the pros & cons of using stainless valves in a marine engine? Thinking of using them in a 302 for the Donzi 16.

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Hotboat

[Forrest]

Stainless steel valves deal with heat better than standard valves. Also, the are many different grades of stainless steel valves out there and as always, the better ones cost more money.

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Forrest

[MattM]

And as marine engines make alot of heat since they are always under heavy load you need at least stainless valves, maybe titanium on the exhaust side. Manley makes a good line of valves, the superduty stainless valves were reliable on my 530 Hp 454. Make sure whatever valve you get that it is a one piece and not a welded valve (they weld the valve to the stem and then machine it)

[rayjay]

MattM,

DO NOT use titanium valves on any hot running engine, especially on the exhaust side! TI valves are really nice and trick, in fact way too light to use as a paper weight, and are VERY expensive. There is a learning curve for getting them to work right, and it is a VERY expensive one. They DO NOT absorb and transmit heat very well. In the endurance bikes we build, we have used TI valves all around and ended up sometimes using them on the intake side for very high speed tracks. On a high speed track, where there is enough cool intake charge flow to make them last, they are worth the cost v return as they are much easier on the valve train. We ran in a National endurance series, and have two class championships, and a second and third in class to back up our experience.

Stick to one piece stainless, with a fairly good size margin on the exhaust side. If weight is a concern, use the "undercut" stem valves and then back cut the underside of face at 30 deg. This will lighten them, and they will flow batter too. If weight, and longetivity, is your concern, you can also get valves with hollow stems. Almost as much cost as TI, and last a lot longer.

If you really want to run TI valves, I will be very glad to sell them to you (and sell another set to you when those burn up, and another set...).

Bet this starts a debate! rayjay

[MattM]

Rayjay, no debate from me, you obviously have more knowledge than me. My only personal experience is with stainless steel, but my machinist kept trying to talk me into TI with my big block in the 22'. I stuck with the stainless. I don't follow your logic on the undercut stems on the exhaust side though. All of the heaviest duty cycle valves that I know of maintain the full diameter stem.

[RickR]

Innovation Marine recommends at least stainless in BBC
Bob Teague says use Iconel on the exhaust side and HD Stainless on the intake in BBC.

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RICKR
mailto:riggerb@aol.comriggerb@aol.com</A>

[Blewbyu]

I used to have a boat with a 1950 Chrysler Marine Hemi in it.That motor had Stellite cooled valves.Didn't know then,and don't know now-what is stellite?Does any one know if it's still available-or is it too "old tech?".

[Forrest]

That must be something like sodium filled or sodium cooled valves. This is a valve with a hollow core in the head area filled with salt? Many German engines builders like BMW, Porsche and VW use sodium filled exhaust valves with great success.

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Forrest

[rayjay]

Blewbyu,

You got my interest there. "Stellite Cooled Valves"? Could you double check that. Stelite is the hard coating they put on the margin of the valve, also used as seat material in heads. Never heard of it being used as part of the cooling of the valve, other than that a significant portion of the heat loss (or cooling) from an exhaust valve happens through the margin of the valve. That's why you want to run a fairly wide contact margin on an exhaust valve, for additional heat transfer. rayjay

[BigGrizzly]

Stellite IS a hard face used on valves, sodium is used as a cooling agent inside the valve stem.
Hond motor has been using stellite on the valve faces since the early 60's. My CR750 has under cut intake valves and sodium filled exhausts, stellite faces on both. This unit is a 1971 sohc engine and turns 11500 rpms. However my Corsican with a 351 cleveland i use stanless valves. This engine only turns 6000 in my boat, and the one in my 1971 MACH I turns 7200 rpms. No need for these stellite or the sodium filled units in the cooler running water cooled engines. Hond also uses stellite valve seats in many applications because of unleaded fuel. Under is nice and common on most high quality SS valves.
Randy

[Owen]

Hotboat, if your 302 is '74 or newer it probably already has stainless valves. Thats when ford put'em in all the 302's due to the unleaded gas.