SBC Rocker arm tick

[53lowdown]

Ok, I'm stumped. I can't get a rocker arm to stop ticking. 1970, 350 chevy engine. Stock cam, hydraulic lifters. Engine was rebuilt I believe about 12 years ago, but has sat for years at a time since then. Oil pressure is normal. I've been using as daily driver for past couple of months, and this ticking I just can't figure out.

Issue: Exhaust rocker on #7 cylinder ticks nearly constantly. Not when first starting, but maybe a minute or two after startup, then almost all of the time. Sometimes at around 1600 RPM it will rhythmically tick for 5 seconds, stop ticking for 5 seconds, and repeat. I've used a hose as a stethoscope - It's not exhaust leak. The ticking is definately coming from the #7 exhaust rocker.

I've adjusted using standard methods, engine off, tdc #1, then tdc#6 per http://berlinetta.info/Lash.htm

Then also with engine running, loosen until clack, then tighten down until ticking stops, then 1/2 turn more.

In fact, it will continue to tick even when tightened so far that cylinder starts missing.

Looked at and measured the stud - it is not pulling out. Checked for weak/broken valve spring by pressing with hammer handle. It compresses same as other valves. Looked at rocker, washer and nut. all look good, but swapped the rocker, nut, washer and pushrod with another cylinder. Still no luck.

Ok, so it has to be a bad lifter right? Nope, just put in all new lifters, adjusted rockers using both methods and Exhaust #7 is still ticking. Can't adjust it away.

I followed this thread with a lot of interest because I'm having similar issues:
http://67-72chevytrucks.com/vboard/s...d.php?t=733510

Any other ideas? I'm thinking about just getting earmuffs....

[jayoldschool]

I had the same problem with my 65 C10. One would clatter. It would go away when properly lashed, but would loosen up. It was solved by a new rocker arm nut, a freebie from my local machine shop. Installed, lashed, two years of no clatter. I've read that you can re-squish them into an oval with a vise, but they are cheap, so why bother? However... seeing that you tried swapping over the rocker and the nut, I'm at a loss.

[lumpy63]

Did you have a good look at the valve stem tip? Look for uneven wearing or pitting. If not my best guess is the lifter.

[lumpy63]

Sorry , you replaced the lifters...

[53lowdown]

Forgot to mention - all new rocker arm nuts also. But that gives me an idea - what if the threads on that stud are bad? All this work and I don't recall inspecting them that closely. I'll take a closer look today.

Originally Posted by jayoldschool

I had the same problem with my 65 C10. One would clatter. It would go away when properly lashed, but would loosen up. It was solved by a new rocker arm nut, a freebie from my local machine shop. Installed, lashed, two years of no clatter. I've read that you can re-squish them into an oval with a vise, but they are cheap, so why bother? However... seeing that you tried swapping over the rocker and the nut, I'm at a loss.

[jchav62]

I've gone up to 3/4 turn past on my rockers.

Maybe a cam issue?

[Reggler]

What about the pushrod? Could it have a slight bend to it?

[Tom]

Cam starting to flatten?

[GASoline71]

Old cam and new lifters... possible cam lobe wiping out and eating the bottom of the lifter too.

Check your oil for fine metal particles in it. Will look like fine glitter.

Gary

[GRX]

In situations like this I start moving parts. Switch rocker & ball assembly from the ticking cylinder with another. If still #7 you know the problem is deeper.

[luvbowties]

Originally Posted by 53lowdown

Ok, I'm stumped. I can't get a rocker arm to stop ticking. 1970, 350 chevy engine. Stock cam, hydraulic lifters. Engine was rebuilt I believe about 12 years ago, but has sat for years at a time since then. Oil pressure is normal. I've been using as daily driver for past couple of months, and this ticking I just can't figure out.

Issue: Exhaust rocker on #7 cylinder ticks nearly constantly. Not when first starting, but maybe a minute or two after startup, then almost all of the time. Sometimes at around 1600 RPM it will rhythmically tick for 5 seconds, stop ticking for 5 seconds, and repeat. I've used a hose as a stethoscope - It's not exhaust leak. The ticking is definately coming from the #7 exhaust rocker.

I've adjusted using standard methods, engine off, tdc #1, then tdc#6 per http://berlinetta.info/Lash.htm

Then also with engine running, loosen until clack, then tighten down until ticking stops, then 1/2 turn more.

In fact, it will continue to tick even when tightened so far that cylinder starts missing.

Looked at and measured the stud - it is not pulling out. Checked for weak/broken valve spring by pressing with hammer handle. It compresses same as other valves. Looked at rocker, washer and nut. all look good, but swapped the rocker, nut, washer and pushrod with another cylinder. Still no luck.

Ok, so it has to be a bad lifter right? Nope, just put in all new lifters, adjusted rockers using both methods and Exhaust #7 is still ticking. Can't adjust it away.

I followed this thread with a lot of interest because I'm having similar issues:
http://67-72chevytrucks.com/vboard/s...d.php?t=733510

Any other ideas? I'm thinking about just getting earmuffs....

I would still remove and swap spring and any shims. Ask me how I know? Hint: too many hours to admit it. HTH; and please let us know; then you and I will compare hours spent.
Sam