Well, thanks for your smart alec answer there Eddie Hascal!!!

Hey Mo... my port engines has 2 seasons on it which is approaching tired considering the abuse. The other engine was new this summer, but I used severe duty manleys instead of the inconnel. I have never had a severe duty fail on me, but I'm not starting now either. So both engines are getting new high end exhaust valves and a clean up on the intakes. What are you guys running for valves stem clearance with aluminum heads?

BT

I actually paid less for 16 Ferrea super alloy exhaust valves than for the 16 Manley severe-duty valves I bought the year before. Not a difficult decision to make.

Thought I would chime in here on valves. Being a designer, tester and builder of cylinder heads maybe I can shed some light here. First, the flows acheived with valves are only a result of the size, shape and size of the valve head (both front and back), valve stem , seat and margin angles and sizes. Flows also vary depending also on seat approach angles, seat size and angles, as well as the throat and bowl dimensions including a plethora of other port size-shapes and lift dimensions. The material of the valve has absolutly nothing to do with flow unless its finish is unusally rough or malformed. Second, the material alloys that almost all high performance engine valves are made of exclusive of titanium, tend to be a alloy of stainless, with additives and structure dependant on the alloy. Inconel is a proprietary name for a stainless alloy with a higher percentage of nickel added to the valve to raise the strength of the exhaust valve when subjected to very high exhaust gas temperatures, lets say above 1350 degrees for sustained periods of use and are a must with supercharging, turbocharging or in a naturally aspirated motor that with its particular setup runs extremely high exhaust gas temperatures. If these Inconel or similar alloys like Ferrea's super alloy are not run with the appropriate alloy valve seat, the benefits of the high temp alloys will be quickly lost. The suppositon that all marine motors need Inconel exhaust valves is a bit of a misnomer. Most Carbed or EFI moderate compression motors with proper alloy stainless valves 21-4N (EV-8 ) or better and good quality alloy seats or high quality ductil iron seats will in most applications, except for all out racing, run just fine and last quite well if the heads are setup with high quality valves with proper size, shape, workmanship, clearances and proper valve fit. Exhaust valve temperatures in these motors that are in excess of 1350 degree temperatures are usually the result of retarded timing, overly lean fuel mixtures, restricted exhaust flow, poor cooling passage design in the head, poor valve seat materials and fit along with cam designs that are just to short on exhaust valve seat time.
Remember that almost all of todays quality high performance stainless valves that are specified and contracted for by Ferrea, Manley, REV, Supertech,etc are produced by just a few valve makers in Argentina. Sad to say, but their are no stainless aftermarket high performance valves made in the "good ol USA" I wish there were, I would buy them first!The valve distributors have diffent alloy specifications they have their valves produced in, so there are differences in the actual stainless alloys each may use. Todays stainless alloy engine valves are for the most part excellent pieces and failures of the valves themselves are rare. Most valve and seat failures in quality alloy valves are generally a result of valve train, misapplication,mismatch or misfit issues and not gennerally a result of the valve material or construction. Even the quality of stainless valves manufactured in Asia have made great strides in quality. As we boaters know, marine engines are the worlds "greatest dynos." The constant loads and sustained high rpms that most high performance boat motors are subjected to will push all parts to the limit, so strength and quality are the operative words here. For those of you who are not sure what to use in your motor, consult a marine engine expert who knows what works. Their will always be lots of opinions on valves, but hearsay in forums can be dangerous to your wallet and boating expierence! Be informed, learn, but be careful!
Class dismissed! Ha!
Ray @ Raylar

Here is a picture of a Manley Inconel and a Ferrea Super Alloy.
I run Manleys because my engine builder sells them. I would have rathered had the Ferreas. I am a firm believer in Inconel exhaust valves after witnessing two failures on a fellow boaters engine who did not use Inconel. He does now and they are Ferreas. Dean Nickerson likes REV valves.
I am sure all the above are good choices.
Good explanation by Raylar Ray!

Ferrea valve is alot heavier than Manley inconel.

Sutphen30,
What kind of problems have you had with the REVs and Manleys?
Were they both of the Inconel variety?
Russ

[QUOTE=sutphen30]which they said would work,stretched and disintergrated.needless to say rev would so much as replace the valves,even after they said it was their fault.

What would a stretched valve look like sutphen30? One my port engine I noticed one exh valve rocker was rubbing the retainer. Looked in the port and see the bronze guide is split above the valve head. Only thing I can figure is the valve has stretch or the seat sunk. Will do more fact finding today.

BT

Don't know off hand but will check with my builder and let you know
Mo

I am using Ferea F1261P super alloys in GM Aluminum heads.What is the difference in the F1271P that is marketed as a light weight super alloy valve.I am assuming it is undercut more under the head.Does this make it weaker???Also what do you guys think about 11/32 stems.I am running them without lashcaps on roller rockers.So far 100 hard hours with no problem.Lastly when rebuilding do you guys grind your valves if they look good or turff em.I am inclined on my next rebuild to buy new 3/8 stem valves and ream the guides.