valve tip damage

[bjones18]

Has anyone seen valve tip damage? I put in SS valves... after a few thousand miles I have noticed pitting on top of some of the exhaust valves, and one tip has flattened (mushroomed - concaved in). The rocker face did not show damage. I am assuming poor oil flow to the mushroomed one.

Where does the oil supply to the valve tip come from? random splash? If it is random splash, why only one valve damaged? I should have taken a pic.

 

[2gdsm_nc]

Valve float? Always heard the sign of valve float is mugged up tops on the valve stems.
And for the 1 being the worst= the weakest spring.
I would check the other end as well as the slamming action can mushroom the head side from it slamming the seat. = easy way to tell if you have done this, valve doesn't hold a seal anymore.

 

[BogusSVO]

also what can happen is when the seats were cut, they were cut deep, making the valve tip too tall, so then the tip was ground to bring it into spec.

when it was ground, it made the harden tip too thin and it just hammered out.

there are 2 types of valve tips, flame harden or it has a welded wafer tip. either one of these can be ground thin.

also if the valve seats were cut deep, the valve spring may be installed loose if there is not a shim under the spring.

 

[turbo23]

another thing, if they were cut to deep, the geometery would be changed possibly loading the tip of valve differently

 

[bjones18]

The seats were not cut, valves were only lapped in. Float may be a possibility.

I just replaced springs/retainers with BCs and 264/272 cams and noticed this damage. I'm trying to hold off till winter to pull the head.

 

[BogusSVO]

so you have stock valves.

do you check the spring installed height to make sure you installed the springs properly?

if not, you may have too much spring tention and your trying to pull the valve thu the seat.

 

[turbo23]

I'm not sure to much spring psi would be as much an issue as coilbind.. takes tons of preassure to tulip a valve, and if it had tuliped to the point that it was wearing the hardened tip of the valve, the lifter would have to completely bottomed out. my guess would be he'd have broken rocker arms in either situation (coilbind or tuliped valve) my guess would be valve float, or maybe a hardness issue with valve. although this could be a result of high egts coupled with a hardness issue on the valve.. not saying the egts have to be higher than normal, but that the valve material is not correct. this would specifcally effect the exhaust side.. this could cause tuliping of the valve and also adnormal where at the valve tip.