slohatch91

exactly what procedure should i follow when installing new rockers and how do i adjust them?

Ls1Bait

What I always do is titen up the pre-lash on the rocker while spinning the pushrod, and when the pushrod dosent spin anymore I tighten it down an additional 1/4-1/2 turn. And my crower RRs have a allen lock on the top of them you tighten down after the lash is set. Now to make sure they all are on a flat spot on the cam (spot with no lobe) I use the method in the haynes manual and you only have to spin the motor over 180* twice and you can do 8 on each turn. More people will chime in on this.
Works well

Lazlo

Wiggle the rockers or the pushrods as you tighten down the bolts. As soon as they stop wiggling tighten another 1/2-3/4 turn. I did mine with the engine running. Tried it sitting and felt like the lifters kept "bleeding out", but my engine had about 130k at the time. Put some towels over the headers and cover the alt with a rag, this kind of makes a mess. Just snug down the bolts, start the engine, Loosen the bolts one at a time till you hear them chatter a little then tighten just until they don't, then go another 1/2-3/4 turn(just do them all the same).

WhyHelloOfficer

iTrader: (5)

This should be of some assistance:
http://shbox.com/1/4th_gen_tech2.html#adjust_valves

Revelation Z28

iTrader: (10)

hot lashing.

slohatch91

whyhelloofficer thanks for the link definatly clears up all questions.

whats hot lashing?

rocket22

iTrader: (2)

THe easiest way is with the engine running and only tighten them done a 1/4 turn,They don't need a 1/2 to 3/4's turn.

pastvertical

iTrader: (1)

its zero lash and 1 full turn

rocket22

iTrader: (2)

I full turn will take lift off the cam because of how far the plunge is down in the lifter,zero lash + 1/4,it will rev higher and take full advantage of the lift on cam.

seawolf06

iTrader: (8)

I agree. I do 1/4 turn preload. Then I get the allen head barely against the head of the stud and then tighten the nut with a wrench. That way it pushes against the allen head and you can get it a lot tighter that way. Then I end up with about 3/8 turn preload.

grn95t/a

iTrader: (10)

i have followed tpis's lt1 hints effects of valve lash on hydraulic camshafts adjustment recomendations on two lt1's of mine and hade no problems with noise or performance. was a bit concerned it was a type-o in the book so i called them to verify the adjustment. they confirmed what was written in the book they supplied to me. it is as follows:

EFFECTS OF VALVE LASH ON HYDRAULIC CAMSHAFTS

" the world challenge series that we competed in durning 1994 and 1995 taught some lessons that were hard earned. because we use motec programmable computer with data logging capabilities i know the exact rpm range that i am asking the motor to operate in. because we are running a special cam, rear end and gear box ratios, the rpm range is very important.

one of the lessons learned is that to achieve elevated rpm's out of the camshafts ( all hydraulic camshafts - flat or roller tappet ) is that you need to preload the lash at least two turns below zero and sometimes more.

the next text series includes airflow data, and from this it is easy to see what happens when you get control of the valve train.

the first test is with the valves set at 1-1/2 turns below zero and the second is with them adjusted to minus three turns. three turns below zero is extreme for the street but two turns is not out of the question. UNDER NO CIRCUMSTANCES SET THEM AT ONE TURN OR LESS. "

now i know what your thinking because i was thinking the same thing! there f@#$n crazy! but the chart they have on page 9 of the book that is with this artical shows clearly that the lb-ft and hp are higher with these settings. so i said before i do this and destroy my cam and lifters and who knows what else ill call them and see. with the stock cam and lifters they said i should go no less then 1-1/2 turns on the street. so i have on two of my last lt1s with no problems.

i know people will be pulling out the so i must say just call them and ask. they are a bunch of very nice guys and dont mind helping.

seawolf06

iTrader: (8)

Wow. So you found zero and then went 1 1/2 turns LESS than that? Was this because they were using the Comp R lifters? I can't see how you wouldn't have valve float or the lifter bouncing all over the cam without any preload?

grn95t/a

iTrader: (10)

no i went 1-1/2 turns below zero. past zero lash.

rocket22

iTrader: (2)

Everyone has there own idea of where to be,I have talked to several engine builders myself that recommend no more than 1/4.

seawolf06

iTrader: (8)

If it was a world challege camaro, I'm sure they were using a crazy cam and some serious lifters, maybe even solid rollers. Then I could see using that much preload. On any stock or stock type, I have been told that would trash the lifters and may not even close the valves all the way causing lost compression. I'm just wondering how much application this has on a street motor. Post up the hp/tq increases.

grn95t/a

iTrader: (10)

the first test is with the valves set at 1-1/2 turns below zero and the second is with them adjusted to minus three turns. three turns below zero is extreme for the STREET but two turns is not out of the question. UNDER NO CIRCUMSTANCES SET THEM AT ONE TURN OR LESS. "

now i know what your thinking because i was thinking the same thing! there f@#$n crazy! but the chart they have on page 9 of the book that is with this artical shows clearly that the lb-ft and hp are higher with these settings. so i said before i do this and destroy my cam and lifters and who knows what else ill call them and see. with the stock cam and lifters they said i should go no less then 1-1/2 turns on the street. so i have on two of my last lt1s with no problems.

buffman

iTrader: (9)

The stock lifters can be done anywhere from 1/4-3/4 turn past zero lash. I dont see how you're getting 1 1/2 turns out of them.. 1.5 turns is putting some serious stress on your valvetrain at high rpms

seawolf06

iTrader: (8)

I agree. Tell us what parts they're using.

rocket22

iTrader: (2)

Anything more than 3/4 is going to collapse a stock lifter.

pastvertical

iTrader: (1)

# Adjust the valve rocker arm nuts until all of the lash is gone.

1. Turn the crankshaft until the cast arrow on the crankshaft balancer hub is at 12 o'clock and the number 1 cylinder is in the firing position (top dead center).
2. Watch the number 1 cylinder valves as the crankshaft balancer hub approaches 12 o'clock. If a valve moves as the arrow moves into position, the engine is in the number 6 firing position. If this happens, turn the crankshaft one more revolution in order to reach the number 1 cylinder firing position.
3. With the engine in the number 1 firing position, adjust the exhaust valves 1,3,4,8 and the intake valves 1,2,5,7.
• Back off the valve rocker arm nut until the lash is felt in the valve pushrod.
• Tighten the valve rocker arm nut until all the lash is removed.
• Zero lash can be felt by moving the valve pushrod up and down between your thumb and forefinger until there is no more movement.
• When all free play is gone, tighten the valve rocker arm nut 1 additional turn (360 degrees).
4. Turn the crankshaft 1 revolution until the hub arrow is at 12 o'clock. This is the number 6 firing position.
5. Adjust the exhaust valves 2,5,6,7 and the intake valves 3,4,6,8.
• Back off the valve rocker arm nut until the lash is felt in the valve pushrod.
• Tighten the valve rocker arm nut until all the lash is removed.
• Zero lash can be felt by moving the valve pushrod up and down between your thumb and forefinger until there is no more movement.
• When all free play is gone, tighten the valve rocker arm nut 1 additional turn (360 degrees).


THATS WHAT IT STATES IN THE GM SERVICE MANUAL, NOW WHEN THERE IS HIGHER LIFT CAM (.600) OR SO I THINK ITS A LITTLE DIFFERENT.