exhaust valves
 

i had a conversation with a friend about the exhaust valves in a 1990 merc 340 hp engine in a cruiser,he said merc installs inconal valves,i thought that merc buys the engine complete with heads installed,and the valves were not replaced with stainless.anybody got the skinny on this?

I'm sure they spec inconnel valves and yes Merc buys complete engines from GM Powertrain.

Wannabe

I've had a few merc engines that didn't have iconel valves. 454 330 mpi had eaton stainless valves $5 a piece.

I doubt mercury installed the valves. GM produced these "marine" 454's, and they were sent out that way. The old peanut port 330/340HP engines were based of the L19 truck engines. They did have different camshafts though. The trucks got something like 194/204 @ .050 cams, the boats got something like 214/218 @ .050. .460/.480 lift, 115LSA But, the Boat cam was a GM grind and came that way. I wouldn't be surprised if at GM, when these engines were being assembled for "Marine", they installed the "marine" cam, Which was actually a late 60's early 70's LS5 cam, and used in some 396's I believe, installed Inconel valves, and probably some other minor changes for the "marine" customers. Gm also used Inconel valves in some of their HD truck engines too.

I suppose though the only way to know for sure if tearing it down. Im sure someone here has been thru these engines and would know.

GM batch builds these engines and yes they are "marine" specs. So tolerances are different, cams , valves etc. :]

Wannabe

thanks for the replies fellas,i didn,t think merc took these engines apart to make changes.it makes sense that gm would build them to mercury,s specs instead,im suprised merc would spring for inconal valves because of the expense but i guess a standard steel exhaust valve would fail before the warranty was up so in the long run they saved money by installing the inconal valves.

Merc only put inconnel in the blue or HP engines.

If I remember right, back in the day, the old HP 420, 440, 460, 465, cyclone engines, and so on, before things got painted blue, were custom assembled at mercury in their high performance division. Which makes sense, since most of those engines had crane camshafts, crane rockers, weiand intakes, etc. Those were not delievered in crate form from General Motors. Same as the new mercury racing stuff.

so maybe as black baja said,these engines got a cheeper ss valve instead of inconal?

Yes that is possible. The black everyday engines they build for Searay, bayliner etc. are built on the assembly lines at Tonowanda or wherever the engines were built. They got crated and shipped to Merc, OMC, Volvo, Indmar etc.

Actually for merc they were buying so many they were often in racks that were returned. Merc would crate them for shipment after dressing the engines and adding the out drive.

Wannabe

Most all of the black engines (454/502 Mag, etc.) actually used a 2 piece valve. The head and a portion of the stem (about half) is Inconel, and the rest of the stem is SS. They did it to save money, since the Inconel material is so costly. If you get a chance, take one of the exhaust valves and put a magnet to it. The magnet will not stick to the head or the lower portion of the stem, but it will stick about half way up the stem. I'm not sure about the older MIE engines, like the 340.
Eddie

I did a LOT of research on this subject about three years ago with my original build. I bought a set of stock square port heads that came off of a Merc Mag engine - NOT a blue engine. The exhaust valve had "Eaton" stamped on it, but no part number. I tried the magnet trick, and it did not stick to them, but I also had a set of standard stainless intake valves that I know were NOT inconel, and it didn't stick to them either, so you can't really rely on that test. I found an article that said that high nickel alloys like inconel will emit a different spark pattern when touched to a grinder than standard stainless material, but who wants to take a grinder to their inconel valves to find out? :eek:

Finally, someone gave me a number to someone at Mercury Racing tech support, and I was told by them that the black motors had whatever GM shipped them with - probably a regular stainless exhaust valve, but he wasn't sure. He did say that the blue motors were disassembled, blueprinted, and put back together with HP components, including the inconel exhaust valves that were sourced from Manley. So that goes along with what a few others have said. I could see where they might go with a standard stainless intake on the black motors for cost savings, since those were generally not HP applications, and I ran non-inconel valves in my old 454 for years, and it held up fine.

A 1990 340 hp 454 definitely had standard passenger car stainless steel valves in it from Merc. Merc did not disassemble the motor or put anything weird in there.

Some of the HP motors (black, before they painted them blue) got opened up for some special parts and pieces, and all of the blue HP motors got hands-on treatment as well.

Some of the rectangle port Mags of the 1990's got different valves.

Some of the later Vortec motors had upgraded valves.

Inconel is a TYPE of stainless steel that is very heat resistant.
MOST "inconel valves" are two piece.

MC