shady_573

I recently had the valve seats ground on my 799 heads and installed them. The motor ran great for about 30-40 minutes and then sounded like it started to knock. I brought it to my mechanic and he said it sounded like a top end knock (valve issue most likely). I took the heads back off and everything looked great except the top of the valve stems looked to be ground down a little bit from the rockers. I am running stock rockers with PRC dual golds and stock valves. Any ideas on what went wrong? I want to get the truck running again but I want to fix the problem before buying new valves and installing them just to have the same issue again. I am running a brand new ls6 cam with the appropriate pushrods (same pushrods that were on my last 5.3 with identical cam, I forget the length)

hirdlej

iTrader: (31)

What do you mean? Someone ground the valve stem tips down or is the rocker gouging the valve stem tip? Pics?

shady_573

The rockers sort of gouged the valve stems I guess. It looks like there is fresh machine marks on the tops of the valve stems but they are uneven and you can see on a couple of them that they aren't perfectly flat any more. I am out of town until next weekend so I can't really get pictures right now.

hirdlej

iTrader: (31)

Soooo why did the machine shop cut the valve stems down? Did they booger up the valve job so bad they're trying to hide their mistakes?