adjusting rocker arms

[crm318]

i am building a 350 with vortec heads. i am in the process of adjusting the valves and i hear that you shoud tighten it till you cant spin the pushrod and then 1/2 a turn. i can tighten it till it get real hard to turn, but i can still turn it. i think i might be tightening it to much though. what should i do?

[VetteVet]

I found this here on the boards. There are other ways to do it, but this should get you up and running. HTH

Adjusting Valve Lash


Written by: Mike Ervin
There are numerous ways to lash valves in an engine. I prefer the firing order method because it works with any camshaft type. The firing order method allows you to lash the valves on an engine stand or with the engine in the vehicle and not have to readjust them again.

SBC firing order: 1-8-4-3-6-5-7-2

STEP #1
Find top dead center for piston # 1:
Many people think that if the timing pointer lines up with the TDC balancer mark that this is TDC #1. That mark could be TDC #6. This is because there are 720 degrees crankshaft rotation in one complete firing sequence. There are two ways to find TDC #1 first is by pulling the #1 spark plug, holding your finger over the hole and turning the crankshaft until it tries to blow your finger away, then once the timing mark comes up this will be TDC #1. The other method requires the valve cover or intake to be off. You can look at the lifters or rockers of #1 and #6 cylinders. When #1 is at TDC, #6 will have both valves open slightly. If you move the balancer timing mark to each side of the timing pointer, you should see both lifters or rockers of #6 moving up and down and #1 should remain stationary. If it is vice versa then you are on TDC #6 and need to move the crankshaft 360 degrees or one full turn.

STEP #2
Adjust the the lash of #1 cylinder:
While you turn the nut down jiggle the pushrod up and down. When the play just stops go 1/2 turn more. You need to make sure to stop when the pushrod just quits moving up and down, then 1/2 turn more on both the exhaust and intake valves.

STEP #3
Turn the crankshaft clockwise 90 degrees:
The easiest way to tell if you have went 90 degrees is with a balancer with degreed timing marks. You can make your own marks if the balancer is off the engine. Just measure the diameter of the balancer (from one side to the other) and then multiply that by 3.14 (pi) to find the circumference, then divide by 4. Example: Balancer measures 8 inches, which would be 8 x 3.14 = 25.12. Then divide this number by 4, which would be 25.12/4 = 6.28 (or real close to 6.25 inches). Then you can lay it off starting at original timing mark and scribe some marks at the distance you came up with. You can also buy timing tape and install it but the only thing is it won't stay on for very long. A total waste of money to me. Anyway, turn the crankshaft 90 degrees to the next mark on the balancer for the cylinder in the firing order, cylinder #8. Repeat Step #2.

STEP #4
Continue adjusting:
Keep turning the crank in 90 degree increments and lashing the valves for each cylinder in the firing order until all the cylinders have been adjusted. Remember, the firing order is 18436572. Do #1, then #8, so on and so on until done. When finished with the last cylinder, you should have to turn the crank one more 90 degree turn and you will be back on #1 TDC.

[Longhorn Man]

personally, I like running them while it is running.
Get them somewhat close and then set the valve covers on with no bolts. A pizza box covering the headers is a good idea, as is a fire ext. It doesn't happen ovten, but I have seen the oil ignite on the headers.
Fire up the engine, run it for a few min at a high idle... 1200-1500 RPM. Then let it idle at 1000 or so, block thew throttle, or just crank up the idle to the 1000 revs.
Pop one of the valve covers off, and use a 5/8 deep socket (small block chevy) a spark plug socket will work if you can't find one (you'll wanna use 3/8 drive). Loosen each one, one at a time, untill you hear clatter. Once you do, start tightening it back down untill the clatter goes away.
As soon as it goes away, you are at zero lash. Stock specs call for one full turn past zero, I prefer 1/2 turn. The engine revs a bit quicker, and in theory, it'll make more power and better MPG... but you'll never see it. Some will say 1/4 past zero, and I have done it myself, but you are playing with fire then. You run the risk of lifter damage.
Now do this 15 more times, and shut off the engine.
Clean your mess, and install the valve covers.

[PanelDeland]

LM,only forgot one thing."Top off the oil!" You will probably lose a little.

[Longhorn Man]

very good point, although, I have never lost more than 1/4 quart... it's a good idea to check.

[ratrod67]

You can also cut the center out of an old valve cover to keep the oil from getting everywhere.

[69CvyPickup4x]

I adjusted my rocker arms by the haynes manual, which said to spin the rocker arm while tightening adjuster nut until rod stops spinning. while that was definatly way to tight because after adjusting them all properly, no spin then 1 full turn. i tried starting the engine and had no compression at all. Instead of spinning, jiggle the rod up and down, while tightening adjuster, until there is no play between the rocker tip and rod. Then 1/2 to 1 full turn after that. Then its adjusted

[Sweet72]

After adjusting them you can look at the push rod seat in the top of the lifter and see if it is still resting on the lifter retaining ring or has compressed into the lifter itself. You want it about .030" compressed away from the retaining ring when the valve is adjusted 1/2 turn past zero lash, this is called "lifter preload". Just a quick and easy check to make sure your adjustment isn't really outta whack before you fire it up.