Why I need SS power valves!

[sideshowBob]

A couple weeks ago 50 miles from anywhere I did a trailside tear down, removing the cylinder head on my 2002 SRX to successfully remove this!
I rode another 100+ miles that day on 2 power valves. Its the third time in 5 years I have broken a power valve. The valve was new last fall and clearance was checked. This issue occurs after or during a multi mile run...3/4 throttle 7000 - 7600 rpm.

If I can't get SS valves I am going to elliminate them all together with plugs in the cylinder openings...run it just like a red head.

 

[bluemonster1]

that is weird bob,I have never had any failure except with pull thru's on original valves.Something not right there.I have done a lot of 1 to 2 mile runs and this has never happened.The SS valves would be nice.Just thinking..if the valve stops do go,would the SS valves totally destroy the piston and rings compared to softer aluminum valves..or would the damage be the same anyways.Your valves must be worn down some and causing them to protrude further into the piston.Hard to believe the end came off and the tapered side was then chewed up.. must of done some piston damage you would think..

 

[bluemonster1]

perhaps you are making to much heat at wot and the aluminum starts to get hot and soft and breaks up ..lets go so to speak...I am lucky so far..mind you your motor has some porting done and perhaps some excessive heat is building up..what is your jetting by the way..just curious..

 

[sideshowBob]

I am running TMX 38s with 360 to 410 main jets depending on the conditions.
I agree this is a heat issue as well as a clutching issue. I run a Team Tied secondary and it keeps the RPMs very low at cruising speeds...my valves don't open until @ 7500 rpm + so they are always down in exhaust heat and vibration unless I am wide open.

I just did a leak down on my engine and the cylinder that ate the valve has 10% leakage...must have stuck a ring as the dome looks fine...time for a re ring this summer anyway.

 

[Ding]

The catches on the cylinder head that are designed to keep the valve from making contact with the piston may be worn off. Who's to say which came first, but as you likely know - adjusted properly the valve shouldn't be able to hit the piston even without the catches, so I am guessing that the valve broke and the bounced on the catches long enough to wear them and finally make contact. I have had a broken cable, and a pull-thru accomplish the same thing, but didn't let it go long enough to cause damage. Just light contact with the piston. Albeit both of these were on a Viper engine.

I would be concerned with a harder valve material. If contact occurs with a harder valve, the piston and rings will likely be toast and possibly even the cylinder.