Say it doesnt sound like this.

http://video.performancetrucks.net/p...4-DCBA128A743B

 

1slowhoe, no, its more tapping than knocking... and its more constant than that. its not a tipitty tip tip tap its a tap tap tap tap tap tap tap kinda thing. as fast as you can say it haha. what is that a sound of?....

 

That is the sound of a broken ring land from the #7 piston bouncing around in the cylinder. So, you dont want it to sound like that

 

I'm going to have to get on board with the lifter being bad idea. I'm not sure what else could be that consistent.

Bent push rod?
Broken spring?
Loose rocker arm?
The truck still runs perfect, just noisy at random times?

 

that pretty much it, seems to run just fine but i have gone WOT in a while because i dont want to blow the trans before christmas.... i am tuned to be running a little rich right now so i dont think its a lean#7 problem. pushrods and springs both have less than 10000 miles on them so i doubt that woudl be the issue. rocker arm...who knows. will this bad lifter damage anything?

 

I've actually had a chromoly pushrod get chewed up and it cause that sound too. However, I do agree...its either a lifter or chewed up pushrod. Oh..and the pushrod had about 6k on it. The noise started about 4k though. It chewed about 1/4 of an inch off.

 

You ever mess with your oil pump? I had similar sound and thought it was a lifter it was the pump pick up o-ring it was the wrong one. Oil pressure registered only a little lower than normal, air was getting in and not letting a lifter pump up.

 

when i had my cam swapped again in june they replaced my timing set with a double roller type... i thought about the oil o ring thing reading about a guy who had this problem too. pretty soon im going to get my heads milled, buy a set of vette lifters from ebay, and swap all that out and see what the deal is then, then if its still being like this ill check the o ring.

these ones http://cgi.ebay.com/ebaymotors/NEW-G...spagenameZWDVW

 

The o-ring can be accessed pretty easy i removed the oil pan. you can remove the crossmember underneath it. I think only two screw's hold your pick-up tube one at the pump and one on the windage tray. V8-kevin is the one that help me with that when i removed the valve cover oil dribbled out of push rod's he told me to check out the oil system that oil should be squirting everywhere making a big mess. your oil pump screw might have also loosend creating a bad seal allowing a little air to get by...good luck hope it's an easy and cheap fix.

 

it is a lifter what is happening it when driving long distances the oil is thining out so i dose not keep the lifter primed and you get your tap try and use some heavier oil like a straight 40w and see what happens i have put 50w in your trucks already so don't freak out just try it and see what happens