I am going thru both my motors this season and I am at a crossroads on what to do with my iconel exhaust valves.

The plan was to replace my Manley iconel exhaust valves just because they have 530hrs on them(1999 vintage). But after talking to a Manley rep. I may not.

The Manley tech said these valves really dont have a lifespan, unless they are pitted on the seat or have any valve stem wear, you dont need to replace them as regular maintenance. 1500 degree egt's is what there designed for. The tech I talked to was more familar with the use of iconel on top fuel engines, then in marine use though.

I've talked to a couple engine builders, who also say they've never seen a failure other then bent from piston failure and such.

Has any one had a Manley iconel exhaust valve fail on them? Any other thoughts?

LE

unless you have issues like high egt,s for extended periods of time,the inconal valve should last dam near forever,listen to the manley tech,he is correct.

The valves should be fine. I got over 700 hours with Merc stock regular plain jane valves. I'm running Inconel now and don't plan on changing them ever.

I would agree with what has been said and what Manley told you.
A valve failure usually is the result of another problem.

I think an OSO member named Full Force tuliped one last year, but amazingly it did not snap the head off. Testament to how tough they are, IMO. I think he had an issue where he was going extremely lean.

Thanks for the reply's. The heads are going in this week to Tom from Gellner's to go over them. He will inspect everything, but I'm sure his opinion is going to be the same.

Quick story..

I was talking to a buddy who knows a Manley sales rep for this area and he told him that iconel valves used in top fuel engines are only changed between rounds because they get so hot(something like 2300+ degree egt's) during a run that the valves left open after shut down can actually start to droop from the extreme heat. They take them back to the shop, check them, and reuse the straight ones.

Thought that was a cool tid bit of info. Needless to say, there tough valves.

LE

Yeah, Im buddy's with Tim. Saw that valve, not sure on that one. It was tuliped with stress cracks in it. But your right, it didnt fail.

LE

yes thats still the mystery valve, even stumped Dean Gellner, he has never seen that before lol and I dont even make any kinda good power!! only around 480 hp... shows how important inconel is to have!

I had 2 regular valves fail in the past.... that made for a bad day..

Yep!! thats me... these things only happen to me Ask LE.... lol

wow,you are a lucky man,that looks like it was seconds away from total failure.