Ratty tat tat under the valve cover.

[wanab5150]

I know some of you have had rocker arm issues but I can't figure this one out. The engine is a Roush 427R/524 HP version with Scorpion rockers and unknown lifters and cam. Roush will not give out the specs. on the cam. The car ran flawless on a 600 mile trip 3 weeks ago and I did not hear anything unusual until I drove it several days later.

I heard a very faint mechanical noise I've never heard before. I could only hear it at about 2000 RPM cruising or on 3500 to 1000 RPM deceleration where it was the loudest. Even then, it was faint.

With my 5 year old ...never used...Harbor Freight stethoscope, I listened to the water pump, alternator and all the lifters through the valve cover. All sounded the same except the #8 cyl. That one spot over the valve cover seemed to have a slight tapping that was not consistent and did not sound anything like a loose rocker.....just an odd noise that was NOT coming out of the drivers side valve cover.

I checked all the rockers and all are free and none are cracked.. So my question is....Does this sound familiar to anyone. Depending which site you read some say roller rockers and roller lifters last a lifetime and others say they last 20-30K miles. I am in the process of re-adjusting the valve lash, confirming the header bolts are still tight and changing the plugs (just because they have 19K on them).

I had one guy state he has heard of the needle bearings in roller lifters flatten out with a high lift cam which will slowly lead to the valve lash being less but other than that I'm out of ideas. Any answers from the Peanut Gallery? Confused Tom. PS............. please pass this on to anyone you may think has an answer or good guess.