Rocker Failure
 

I went to take the car for a spin today and enjoy the weather a little. I warmed her up and then proceeded down the road. About 1/4 mile into the trip I noticed the sound of an exhaust leak or puffing from the driver side exhaust. A few seconds later I start to hear a light tapping from the motor. Instantly I pull it over, shut it off, and pop the hood. Everything looks OK. Start it up and I get a loud tapping from driver side #1 cylinder. Pull the spark lead and it stops. Great....something let loose in the new motor. Managed to limp it home and pull the valve cover and this is what I found....

http://i20.photobucket.com/albums/b2...Failure002.jpg
http://i20.photobucket.com/albums/b2...Failure003.jpg
http://i20.photobucket.com/albums/b2...Failure004.jpg

None of the parts of the rocker actually broke off....just spread like an orange opening up. I spotted a few very fine particles but nothing major. So now I would like to find a good quality upgrade rocker set that I can still fit under my stock 396 valve covers. Any ideas?

Well, I pulled the rest of the valvetrain out this morning and found a few more issues.



http://i20.photobucket.com/albums/b2.../Valves003.jpg



I have a bent #2 pushrod and several are slightly darkened in the centers. Is this discoloration from stress?



http://i20.photobucket.com/albums/b2.../Valves001.jpg

#7 exhaust rocker looks to be getting super hot as the oil is burning on the rocker and nut. Any ideas what is going on here? This is the only one that has an issue.



http://i20.photobucket.com/albums/b2.../Valves002.jpg



All the other rockers seem to be fine. I don't have any galling on the pushrod tips at all. I noticed the guide plates on the pass side have a little wear but there is nothing really on the pushrods themselves.

Its funny how the technology moves.

If the lift is beyond the mechanical abilities of the rocker, they bind and break through eventually. The rocker that has the "ball-o-sludge" is due to lack of lubrication at some point. It got hot and the oil that made it to the rocker was baked in place. You need a good set of roller rockers or a set of long slot stamped rockers. Use cam lube on the pivot balls for the initial start-up.

I would add to that by mentioning that from the photo - while it's very hard to tell - but it appears that the rocker is riding on the "top" side of the valve stem... it looks like there is a 'wear pattern' near the top third of the valve stem tip.

You might want to use a push rod length checker - and make sure that the rocker is riding (use a felt tip pen to coat the valve stem - then crank the motor through a full swing up and down on that valve with the rocker in place) in or very near the CENTER of the valve stem. The "witness mark" that the rocker will make against the coated end will tell you where it's at.... if the push rod is too short - it'll ride on on the top end (intake side) -- too long and it will wear on the bottom (exhaust side) of the stem.

You might also want to check for coil bind as long as you're at it. And check the underside of the rockers to make sure there are no witness marks from the bottom of the rocker contacting the spring. As long as you have it open - might as well cover all the important bases!! :thumbsup:

I did check the contact on the top of the valve stem and everything looks square. I don't see any off center wear marks. I have no contact on the under side of the stock rockers either, just the contact point for the valve stem. Everything looks good.

GREAT! Scratch a couple more items off the list "eh"!!

Hope this all works out for you!