Cam Wear

[Kennymonster]

Did Delta regrind the rockers also?

I know that it's not popular subject or recommended by many on here, but when I consulted with the Schneider guys regarding the rockers, they recommended that I inspect and if 'smooth', reuse the stock rockers - to my surprise.

He actually advised against resurfacing the rockers (due to the chance of whomever performing the task improperly), and also warned against lot of the 'new' rockers out there due to being inferior Chinese material.

Just barely have few hundred miles (if that) on my setup, the 270/280 .460 Schneider regrind on stock cam with their springs. Used their rub on break in compound + fluid and seems to be ok so far, but hopefully I don't meet the same fate after 2k miles if the springs indeed ended up being at fault.

[240260280z]

Thanks Kenny,

Yes the rockers were Delta regrinds.

btw the car has the same cam as yours but with schneider springs and retainers.

[Lazeum]

Did you control valve clearance before taking it out?

I had a major cam failure with rocker pads so damaged that one broke into pieces only after 300mi after head rebuild.

I found no evidence of oil galleries being plugged. D. Rebello told me after having seen pictures that it was due to poor lubrication (destroyed brand new cam was coming from his shop).

My analysis was that valve lash has reduced to none after some miles. So no gap existed anymore, lubrication did not occur properly, heat was created, metal treatment disappeared with heat resulting in total failure (cam lobes severely ground, metal chips everywhere inside engine, crankshaft bearing destroyed, oil pump damaged, etc.)

Since full rebuild, I've checked valve clearance every 100mi. I've noticed valve clearance decreasing dramatically on the first 500mi. Since, I've run the car for +1000mi no problem, valve clearance does not move anymore.

Edited August 2, 2013 by Lazeum

[240260280z]

That is interesting. The first cam seemed to go that route.

On that one I checked the valves a 0mi cold then hot, 50, 500 and 1000mi with only two needing a minor adjustment at 500mi.

[240260280z]

Good news Jim, you were spot on! I put ~1000km on the cam with a new rocker and both look fine. Even the discoloration is gone from the cam and only 2 fine scratches remain. The new rocker looks perfect.

Now with ~600km and enjoying ZCON here in NH (wish you were here!!!!) I'll take a photo and post later.

[zKars]

Fab! Now you can relax and enjoy the show.

Now is this a one off problem with that rocker, or do we have to be "careful" with re-worked rockers?

Wish I was there too. Guess I'll have to live this ZCON thru you'z guyz. Enjoy the ride! Literally!

[Jeff G 78]

So what was the root cause? Did the clearances change causing the heat and wear or was it a rocker arm problem?

[240260280z]

Hi Jim,

Looks like it was a poorly ground rocker that had a high spot. See post #23 above (bullets 2 & 3) Jim hit it on the head.

Edited August 5, 2013 by Blue