Corvoid

Had a blown head gasket. Decided it was time to fix her up.

-new head gasket
-refurbished cylinder head and cam (original rocker assembly)
-stock carb
-all anti-smog components removed
-timing set at 0...vacuum advance hooked up and works ok
-new flywheel, oil pump, water pump
-new aftermarket timing chain, tensioner, and guides. New timing cover.

Ran a spark plug wire removal test with the truck running (looking for noise coming from a particular cylinder) but the noise remains unchanged with any plug wire removed.

Compression test was good. Oil pressure measured and seems good.

The valves are lashed to about 0.18 mm intake and 0.27 mm exhaust.

Help! I'd like to fix this before deer hunting season.

Corvoid

This post has been up for about a week with no replies.

Was hoping for a bit more feedback.

I encourage the experts here to at least give some guess as to what the noise might be. I'm pretty sure it's something in the top end.

Maybe something having to do with the mating of the new head/cam with the old rockers?

Corvoid

Wow. No help from anyone?

I am still at my wits end trying to diagnose this noise, If anyone would be generous enough to chime in with an opinion, I would be grateful.

mwisham

Have you checked the valve adjustment since installing the head? These engines are notorious for valve rocker tapping noise. Does the noise get better or worse as the engine warms up? Have you looked at the inside of the valve cover to see if any of the rockers are hitting the bottom of the cover? That happens a lot when people overtighten the valve cover nuts.Get a mechanics stethascope and see if you can narrow down the source of the noise. It would be very hard to determine the cause just by listening to the video.

Corvoid

With a mechanics stethoscope, the sound is incredibly intense from the front passenger side acorn nut/stud of the valve cover. If that acorn nut is removed, and the stethoscope put right on the naked stud, the sound is about the same. The other three studs are loud too, but maybe only a third or a fifth as loud. It sounds like a hammering on the front corner of the rocker assembly.

It apparently not simply impact of rockers with the valve cover. I have loosend the acorn nuts, and even lifted the cover a few mm, and there was no change in the sound.

I've adjusted the valves numerous times, both cold and hot. Even tried 0.005" on all eight valves while hot, which is way below spec. No change.

Swapped out the mechanical fuel pump today. No change (dang! I was hoping that was it!)

It makes little difference if the engine is cold or hot. It is more dependent on rpm.....faster makes the noise faster and louder.