Ajusting valves (zero lash)???

[Dirka]

I know everyone has their own way of doing things and I'm sure it's been posted before, but here are 4 that I would like to get a vote on. Everything I've read about adjusting the intake valve is the same. (adjust it when the exhaust valve just begins to open) My question is I've read 3 different techniques on how to adjust the exhaust valve.

1) I don't remember the site, but it said to turn the engine over until the Intake valve is almost closed, then adjust the exhaust valve rocker to zero lash and then 1/2 turn

2) From comp cams and another website "turn the engine over until the intake pushrod moves all the way up. Rotate just past maximum lift, where the intake will begin to close. The lifter is now at the base circle, and the exhaust valve can be adjusted. Note: DO NOT go too far down (over halfway) past the point of maximum lift. If you go too far, you will be in the overlap cycle – where intake valve lash is being taken up as the exhaust valve begins to open."

3) As you rotate, look at the intake lifter or pushrod of the number one cylinder. The exhaust will open first and then the intake. As soon as the intake returns to its lowered position, stop rotating. The cylinder is now on its compression stroke and both lifters will be in their lowered positions.
For adjustable type rockers, spin the pushrod with your fingers as you tighten the rocker nut. It can be difficult to tell the exact point where all the slack is gone and the pushrod becomes a little harder to spin. While you're turning, feel for a slight difference in resistance to spinning the push rod. That should be the zero lash point where the pushrod is unable to move up and down at all. When you get close to zero lash, it helps to hold the wrench up a little bit, so that the socket is not sitting on top of the pivot ball.

4) Says to adjust them while engine is running, take one valve cover off and loosening until clatter, then tightening down until quiet and then another 1/2 turn.

Thank you.

[454Man]

I'm in for#3

[ehjorten]

To me the EO/IC method (method #2) is way too much rotating of the engine by hand!!!  I prefer method number 3, but I usually just confirm that I am on #1 TDC with the distributor and then start there, rotate the engine 90° (a full timing tape or damper marked every 90° helps), move to the next cylinder in the firing order.  Once at #1 TDC you only have to rotate the engine through 2 revolutions to be done.

Method #1 is incomplete in that it doesn't say when to adjust the Intake valve, but we can figure it out just by knowing what is happening inside the engine.

The 'zero' lash + 1/2 turn is a valid method for hydraulic lifters only.  You didn't mention that.  Solid lifters are a different story.  What you are really looking to do with the 1/2 turn is set the hydraulic lifter pre-load.   What you are looking for is about 0.030±0.010" preload.  If you have 7/16"-20 rocker studs then 1/2 turn equals about 0.025".  If you have 3/8"-24 rocker studs then 1/2 turn equals about 0.021".  So this is where the 1/2 turn comes from.

For higher RPMs you actually want to be a little light on the pre-load, but for street-only with RPMs with a max of around 5,000 you can tolerate being a little heavy on the pre-load.