Ok, I bet the answer is I'm driving it too hard, but at least once a year (ever since I replaced the old 2-piece valves with stainless)I seem to shear at least one spring keeper pin. It happened again yesterday, so I took the valve cover off and replaced the broken one. Then I noticed another was ready to go, so I pulled it. What I noticed is that it looks like the steel pin is actually being ground away by the "cup" under the spring. Here's a photo of one that is ground almost in half. Are the new pins too soft or is there something wrong with my valve clearances?
Maybe your valve springs are stiffer than standard ones. I have never seen that happen before.
Chris, there was some bad ones out there a few years ago that where too hard, yours looks as if the springs are Model A springs in there. That will even cause the valves to mushroom out with that much pressure.
To me it looks like they are to soft. See if a flat file edge will cut them.
The only time I have seen those pins wear like is when nails were used in place of the pins.
My question is why are the valves moving so much in the cups? Is it possible your valves arent reamed in line and the cups are wearing on one side of the pin?????
How worn out are your cups???? If the stem is loose in the cup its possible you may need to change the cup cause it'll wear side to side.
My point is there shouldnt be any real motion in the area you are seeing wear.
On some rebuilts after a lot or miles, I have seen the pins cutting their way into the washer that the spring rest on. Also some wear on the pins, but I repeat, that was on a well worn engine.
The pins that the vendors sell are too soft. After finding the same thing that you showed in your picture I started making my own pins from drill rod that I bought from McMaster Carr.
That sounds plausible. The valves, springs, cups and pins were all new and replaced together a couple years ago (2010 if I recall). They were all from Lang's or Mac's, but they probably all have the same vendors. How did you cut the drill rod?
Drill rod in itself isn't that hard. Cut the pins to fit, get them red with a torch, then quench them in water, or oil. ws
You can cut it with a Dremel loaded with a cutoff wheel if you don't have a cutoff saw. If you're not going to harden the pins, use D2, A2 or W1 drill rod (in that choice order). These are pretty hard (C36 - C30) in their "as supplied" state. D2 will give the best wear resistance but W1 and O1 are the most forgiving for hardening. The others use an involved hardening process that is pretty strict for good results.
I cut the drill rod with a Dremel as Ken posted. I am fairly sure that I used A2 and I did not harden them. I have 2 cars with these pins in them and have not had any reason to pull them down for inspection. I drive them both of them about between 1000 to 2000 miles a year. The pins have been in for 3 or 4 years. I should log these things.
I have done the same with the drill rod on a Henderson motorcycle with good result's. Been several years and around 4,000 miles, their holding up very well. I did git them dull red and put in oil.
If your going to heat and quench be sure to temper when your finished. Heat and quench hardens and causes embrittlement while temper eliminates the brittleness and toughens the material. Though they should both be controlled processes it's not necessary to find the grand priestess of metallurgy to perform them. The different materials can be hardened and tempered utilizing the color of the material before quench and when tempering. With some materials, not all materials, but some it's possible to heat and oil quench and maintain toughness in one process. It's important to know the recipe of your material. i.e. carbon, nitride, chromium, lead, nickel and other materials . A Rockwell C-30 to 36 should more and suffice for the required application. You might be surprised at how much information the wholesale metal suppliers will give you during a phone call to their marketing people. Good luck and God bless.
I've had good luck just buying cheap drill bits by the job lot and using the dremel to cut them. Flea markets are a good place to find such. KB
Are all spring keepers from all vendors of the same inferior quality?
Where did you get the valve pins from? I supply the ones Lang's currently sells and they are hardened. Several years ago there was an issue with the pins being to soft and I responded by manufacturing hardened pins. I don't know of any complaints since. I can not say where anyone else gets their pins from, nor the hardness of them.
I had the same problem a coupla years ago and went the drill rod route, IIRC I just cut the drill rod w/a hacksaw.