Help me diagnose this noise

[brielly]

A little background-Cylinder head just had valve job. Replaced head using old rockers, pushrods, lifters etc. Changed oil. Engine ran fine before this but was always a little louder after an oil change. The noise is much worse now and seems to be coming from under the valve cover. Here's a video of it running https://youtu.be/Ju5cTCe4Vm4 https://youtu.be/Ju5cTCe4Vm4

I guess I'll start by pulling off ther V/C to have a look?

[tgreese]

Exhaust leak? Inline 6s are very susceptible to exhaust leaks between the cylinder head and exhaust manifold.

I'd use an automotive stethoscope or even a piece of rubber tubing in the ear to better localize the noise first. Careful you don't pipe hot exhaust gas into your ear.

[rocklaurence]

My guess-lifter tap. Did you set valve lash on the rockers?

[tgreese]

My guess-lifter tap. Did you set valve lash on the rockers?

Your hydraulic lifters have a lash range over which they will operate. The speed shop sellers have an adjustable pushrod you can use to measure the maximum length with a collapsed lifter. You then compare this to your current pushrod length to see if you are in the range. Height of the valve stems could have changed with the valve job. Looks like a 4.0L HO head on a 4.2L block? Would not be surprising that the pushrod length is not ideal.

[brielly]

The exhaust manifold and gasket are both new so i don't think there is an exhaust leak. I used a stethoscope and the sound is loudest fromn the valve cover. Its actually a 4.2 head from an 83 engine. The bock is 82. I checked today and there are different length pushrds for those 2 years plus the head was shaved. I guess I'll have to find m y old pushrod length tool or order a new one. Was hoping to bolt the new head on and go but i cant be that lucky.

[brielly]

Using my pushrod checker I found the intake valve needs a 9.64 and the exhaust needs a 9.59. This is factoring in for a .040 preload. Rock auto sells a 9.6210 pushrod. Is this size a good compromise?