I was going to ask you if you knew for certain that those are inconel valves, but it sounds like you installed them yourself. There is a lot of confusion as to whether or not the Merc motors are all running inconel valves. I talked to a Mercury Racing tech on the phone last year, and he stated that the blue motors are definitely running them because they pull the valves and install Manley inconel exhaust valves. However, the black motors are running whatever GM installs in the base engines that they shipped to Merc, which I believe is an Eaton valve. Whether or not the Eaton valve is itself inconel I could not determine. I know GM is running inconel in their diesel engines, but as far as I can tell all of their gasoline engines are running standard stainless exhaust valves.

After talking to Bob Madara on the phone the past couple of days, I think I am going to pull the Rev exhaust valves from my engine this winter and install a set of inconels. Apparently, according to Bob, high speed cruising at 3800 - 4000 RPM can get the valves hotter than a full throttle blast. They spend so much time off the seat in these conditions, under high load, that it is tough for heat transfer to take place. The inconels can handle the heat stress much better than a regular (even high grade) stainless valve.

FullForce, if you only replaced the one failed valve, I would consider going back through it this winter and replacing the rest of them. You might have some others fatiguing that may fail in the future.

I installed them myself and purchased inconel...you can check with a magnet inconel is not magnetic..the magnet should grab about halfway up the shaft where it is fitted to stainless..

I had a clogged fuel filter that caused lean condition.. that is alean cylinder anyway.made it worse

Dean gellner said inconel are pretty much no limit valves until you ruin em. He has race boats with lots of time on inconel valves he has told me...

Oh yea.. the reason 3800-4000 is hard on em is that's around where torque and hp mix causing the most heat

I have found that the magnet test is not always a good indication that you have inconel. Yes, a magnet definitely will not stick to inconel, but it also will not stick to most regular stainless valves. I have a set if stainless INTAKE valves that a magnet will not stick to.

I read that you can sometimes tell if it is inconel by the sparks that are emitted by a grinding wheel, but who would want to do that to their expensive exhaust valves? :faint2:

I knew these were anyway since I bought em and did my own work.... but anything can happen in a boat engine!!!!

You got that right!

Was there any part number or markings on the valve(s) that you bought? Did you purchase the Manley Extreme Duty valve, PN 11587? I'm asking because there's a set for sale on ePay for a low price - seller states that they are new but not in original packaging. He refers to them as "bulk pack". Color me suspicious unless there is some way for me to know for sure that they are really the inconel valves and not some cheaper alloy.

Thanks!

Part number seems right....the magnet trick was shown to me by Gellner he's a well known marine engine builder here.... that part number is right I think.....don't have paperwork in front of me.... new valves should be in vacuum bags

I was hoping that there might be a part number etched onto the stem somewhere. I don't trust the magnet trick anymore when I saw that the non-inconel REV valves that I am using now won't hold a magnet either.

Full force are you going to cumberland next week?

Nope....actually staying on mainland