tappet adjustment

[hilandr452]

Hi guys,

I have some minor tapping in my valve train on one side which I believe to be rockers on the valves. It's not too bad but I've been told that these can get worse and cause damage if left unadjusted. It's a big block 402 and runs very strong. I know I should look for bent pushrods and that the hydraulic lifters might be bad, but it is really minor and I think it can be fixed by adjusting the rockers. Can someone please walk me through the adjustment process?

Thanks in advance.

Dan

[Tynee]

A good write-up in the FAQ section:

http://67-72chevytrucks.com/vboard/s...d.php?t=219649

[hilandr452]

Perfect!!
That's exactly what I was looking for! I apologize for not searching first myself. Thanks a bunch!

Dan

[Tynee]

No apologies needed. That's the way this is supposed yto work, those of us who have been around a little longer show the newer guys around, make 'em feel at home. I know there are guys who do that for me every day.

You know, I was thinking about this, and I've always heard loose/ out of adjustment valves manifest themselves as a "clatter" more than a "tap." If you are hearing more of a "ticking" sound, this MAY be a sticky lifter, instead of loose valves. No matter what, you won't hurt anything making sure your valves are properly adjusted. Where to go from there if adjustment doesn't solve it, is a bridge that can be burned when you get there, right?

[hilandr452]

It's definitely a tapping sound, similar to what my chevy luv sounded like when the valves needed to be adjusted. It can only be one or two cylinders because it is well defined and just on one side. You're right though, adjusting them all properly will eliminate the possibility and I'll know what to do next.

thanks again.

Dan

[windmill]

The big block chevy will wear a lobe off if left too long without adjustment.

[Kayotic]

Do you hear this constantly as the engine is running? I have a noise from somewhere under the hood I don't know what it is. It almost sounds like the butterfly plate is ratteling on top of the carb. I can't locate it cause it only happens under load and under throttle. When I come off the gas it stops then when I am back on it comes back. Listening to the truck idle though it sounds fine even when revving the engine. Only under load. It is a v6 4.3l in an '86 DD.

[Tynee]

Originally Posted by Kayotic

Do you hear this constantly as the engine is running? I have a noise from somewhere under the hood I don't know what it is. It almost sounds like the butterfly plate is ratteling on top of the carb. I can't locate it cause it only happens under load and under throttle. When I come off the gas it stops then when I am back on it comes back. Listening to the truck idle though it sounds fine even when revving the engine. Only under load. It is a v6 4.3l in an '86 DD.

I had a heat sheild on the catalytic converter that did this, drove me crazy. good luck!!

[Kayotic]

Tynee - not to rob this thread but add to it.

Thats what I was thinking. I do have that valve in the exhaust that is disconnected and could be flapping around. Just been hard to hear it while moving, these square body trucks are wind noisy. It's been going a long time now and as of yet not broken anything.

[hilandr452]

Yes, you hear it as a constant tapping sound. It's noisier when cold which makes sense with these hydraulic lifters. I can't wait to get healed up so I can go out there and adjust them.

Dan

[Tynee]

Healed up from what? I must have missed a thread or 12...

[hilandr452]

I am at home recovering from hernia surgery. The thing is right in the center of my considerable belly. This is the second try in two months as the one I had in December failed and the hole was bigger. They did laproscopic this time which means basically that they run you over with a 2 ton truck several times and call it good.

I can do menial tasks but can't lift over 10 lbs for 6 weeks and am stuck in my house for the next week and a half while my truck sits out the not being worked on. I'll probably get some minor body work done but am really just supposed to sit and heal up.

Stupid hernia....

Dan

[Tynee]

brutal. feel better, my friend.