Hey everyone I have a 68 convert, 427/390 4speed that has some ticking sounds coming from under the valve cover. Sounds like the lifters are loose. I made a dumb mistake when I was changing the new valve cover gaskets because of a small leak, I noticed a few of the lifters were loose and I tightened them a bit until they wouldn't wobble anymore. Unfortunately I completely forgot that this is a hydraulic system and that the pressure releases eventually. How do I go about tightening or loosening these to the correct specs so that the noise stops? Any recommendations are greatly appreciated. Thanks everyone!

 

I recently had the same issue. Chilton's repair book gives the specs if you are brave. I took mine into the GM dealer. I spent 300.00 but I thought if something went wrong it was on them. The book can be orderd from Auto Zone for about 30.00

 

I use this same method. this is from 427Hotrod

First you have to roll the motor around to set each valve right? The cam has to be on the base circle. Easiest way for me is to set them as follows:

1) When the exhaust on a cylinder is just starting to OPEN...set the intake valve on that cylinder.
2) When the intake is almost CLOSED..set the exhaust on that cylinder.


So back off all the valves until they are loose and then start bumping motor over watching the valves as above.

Once you get it on correct position to set each valve...you want to reach down and pinch the pushrod between your fingertips right below the rocker arm. Lift it up and down with the nut backed off. You want to slowly tighten the adjuster nut just until that up and down slop just barely disappears. You want to just BARELY take all the slack out of the assy. Don't overtighten...you just barely want that up and down wiggle to be gone. It only takes finger tip action...you will likely still be able to spin the pushrod when you have just barely got it to *O* lash.THAT is *O* lash.....the lifter plunger is up and you have no play in the pushrod/rockerarm/valve. THEN you tighten the 1/4-1/2 turn to put the lifter plunger down in the lifter slightly.

Repeat by bumping the motor around for each valve....it will run then just fine.


Good luck! Instructions by 427 HOTROD

 

I'm sure that this will get a lot of critisim but here goes.
The process described above is the correct way for pre startup.
After start up I adjust them with the eng running. back them off one at a time untill they make a slight noise then tighten till noise stops and then tighten slowly acording to specs ( SB I beleave 3/4 turn). this centers the plunger in the lifter.
Yes you will get some oil spillage,I got a cheep pair of valve covers and cut the top off of them to help with the oil spillage.

 

I've been adjusting hydraulic lifters that way for 35 years. I use 1/4 to 1/2 turn after they stop making noise. Back off until they rattle, slowly tighten until they just stop making noise and then 1/4 to 1/2 turn more.

 

Also on this. I have the specs for a 1978 all motors. I don't want to give those to you because they are probably different. There is a torque spec on the bolts for the rockers. And a gauge settting for the valves. Hope this helps Gary

 

Exactly what I have done for 30 years as well on multiple SB V8's!!! Works perfectly!!!

 

68maroon both methods will work. 427s method is less messy and I feel more accurate.
If you choose the running method make sure you have a way to stop the oil from running and or spraying on your exhaust manifolds or headers or there is a possibility of fire not to mention the oil that runs down the side of the engine and ends up on the floor.

 

I made a set of valve covers with the centers cut out to allow running adjustments without all the oil leakage. I back the rockers off until they begin to chatter. Then tighten them only until the chattering stops (zeero lash). Then tighten in 1/4 turn increments until you are about 3/4 of a turn.

 

I'd note in passing that you will never see an engine shop or racing team adjusting valves while running. In my experience adjusting while running nearly always creates too much preload. It does have the advantage of not requiring the "feel" of finding zero lash.

DWncchs method is accurate in every case. If the cam isn't radical, you can also use the companion cylinder method which is very fast and acceptably accurate on streetable cams.

 

Must be for lawn mowers. No SB chev with a hydraulic cam is adjusted in this manner.

 

I have used 427's method since it was taught to me in 1974. Never had a noise or a problem. The other method is a mess in my opinion and that's an understatement. Don't clearly understand why somebody would use it unless they don't know about the easier less messy approach. Not trying to be offensive just stating my opinion

 

I've used both methods; running and companion cylinder. Since learning companion cylinder, I've never used running. Like the others have said, its messy, and the oil running all over the place will likely cause you to hurry the procedure. For everyday driving, either will work.

 

You must be referring to rocker studs, correct? There are no "bolts for the rockers"

 

Maybe he is thinking about an Olds or Buick with the rocker bars,Cadillac also had those at one time.