rocker/valve adj HELP!

[idaho66stepside]

I put in a 350 into the ol' 66 and adjusted the rockers/valves and all is well until the next day when I have time to drive it and it sounds like the rockers loosen up on me. This has happened twice so far and this is the first time that I have done a valve/rocker adj. What I have been told and have been doing is loosen till you hear the clatter, tighten until it stops, then tighten one to one and a half turns. Is this correct? Should they loosen up like that? Is the procedure different on aluminun(sp) heads vs. cast iron? Thanks guys

[fleetsidelarry]

idaho, need some more engine info.

used engine, new crate engine or newly rebuilt.
new cam, valve train, if so, what break in procedure
what heads, old (anything done to them) or new after market

a number of things could be happening depending on what you started with:

locking nuts are worn and loosening up (reused old nuts on old studs)
studs are pulling out (new spring pressure too much)
cam is wearing (proper breakin not followed)

bottom line is "tell us more"

turn and a half is too much preload in my opinion but might be factory specs on stock cam/lifters.

[GASoline71]

The process you're using to adjust the valves is with the engine running. Is that how you're going about it?

Only tighten to a 1/2 or to 3/4 quarters of a turn. Stock is one full turn.

Did you break the engine in correctly with the proper break in oil with enough ZDDP? You're also describing exactly what happens when a cam starts wiping lobes and eating lifter bottoms.

Gary

[Captainfab]

Another thing to look at is the rocker arm studs if they are pressed in. If your heads were rebuilt, and the rebuilder got the heads a little too hot during the cleaning process, that will loosen up the studs. I chased a problem like this and it ended up being the rocker studs were working their way out.

It could be your cam going flat, if you didn't follow the breakin procedure, and with the correct breakin additive, and correct oil there after. If you're tightening the rockers 1 to 1-1/2 turns, that is too much. 1/2 to 3/4 turn like GASoline71 said is what they should be.

[fastwillie 696969]

first of all try adjusting them the correct way ,
Here are step by step instructions:
Remove the valve cover.

Identify the number one cylinder. See the page on Firing Order on the menu to the right if you are not sure which cylinder is number one.

Turn the engine over until you see the number one cylinder exhaust valve rocker arm JUST START to move from the closed position to open. You may need to turn the motor over a couple of times to reach this point, but do not turn any further.

Locate the intake valve.

Loosen the rocker arm adjustment nut until you feel some obvious lash or clearance in the adjustment.

Using the thumb and index finger of one hand, grasp the intake push rod below the rocker arm, and rotate it back and forth (clock-wise and counter clock-wise successively to be sure there is no remaining pressure on the push rod from the rocker arm as you loosen the rocker arm adjusting nut.

Using the other hand, while continuously performing step 6, with a 5/8 socket and ratchet, tighten the rocker arm adjustment nut slowly until you feel a resistance of motion on the push rod.

This will be the zero lash adjustment point. For hydraulic lifters, tighten the rocker arm adjustment nut 3/4 of a turn. For solid lifters, back off the rocker arm adjustment nut until your feeler gauge just fits under the contact point between the valve stem and the rocker arm. Fine tune the adjustment by checking it with a feeler gauge just slightly thicker than the preferred clearance to be sure the clearance is not greater than it should be. If the larger feeler gauge will fit, it needs to be re-adjusted. A lash tolerance of 1-2 thousandths of an inch in the valve adjustment for solid lifters would be acceptable since it may be difficult for someone who is in-experienced to be more precise than that.

Turn the engine over until the intake valve opens and then is almost closed.

On the exhaust valve, repeat steps 5 through 8 for the exhaust valve adjustment.

Repeat this procedure for each cylinder. Be sure to do each cylinder sequentially, either following the firing order, following the cylinders numerically, or in the case of a V8 doing one side of the engine at a time. I prefer to do one side of the engine at a time.

[idaho66stepside]

Thanks for the pointers guys. I didn't give ya'll enough info did I. I'm thinking it could very well be a cam/lifter problem. The engine was a friend's that was rebuilt and used a few times and I'm pessimistic about the break in that was done. He has rebuilt a bunch of sbc's and is helping out. I put some new edelbrock e-street heads and the rockers from a different 350 but I didn't pull out the newer cam/lifters and reused the rv cam already in it for this swap. Prob a dummy move.

At first I did tighten the valve 3/4 turn then the second time went one full turn, all while the engine is running, starting with #1 and adjusting one side then the other. And it sounded good until driving just a couple miles to the tranny mech for it's new 200r4. Hooking those up makes in nervous. Does it sound like I'm pulling this thing and buying a new cam/lifter?

[tasian]

well if your cam is going flat your most likely looking at a full rebuild because of all the metal that is now in the block from the cam but adjusting valves with the engine running is rarely ever close to right use the method fast willie posted and go from there just take your time and if you don't feel 100% that you have found zero lash just back it off and do it again but once you do a few you'll get the feel for it

i also prefer to put a piece of tape by the valves i have adjusted to keep track and make sure you get them adjusted ASAP! that much preload isn't going to help the cam at all

[GASoline71]

Agreed... I've seen some pretty scored up cylinders and piston skirts after a cam failure. Not to mention all the bearing will be trashed. The engine will need a thorough cleaning, and make certain to get all the trash out from underneath the baffle in the oil pan if you reuse it.

Gary