Hi,
Just looking for a little help on setting the valve lash on my motor. I have the general idea but i would just like to know the exact procedure and the proper tools need. I have a gm 350 with the long block assembled minus lifters and pushrods being installed. The heads are fully assembled also. Please any information would be helpful.
thanks
-tom

 

Here are step by step instructions:

1. Remove the valve cover.
2. Identify the number one cylinder. 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.
3. Locate the intake valve.
4. Loosen the rocker arm adjustment nut until you feel some obvious lash or clearance in the adjustment.
5. 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.
6. Using the other hand, while continuously performing step 5, 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.
7. 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.
8. Turn the engine over until the intake valve opens and then is almost closed.
9. On the exhaust valve, repeat steps 5 through 8 for the exhaust valve adjustment.
10. 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.

 

Yep, that pretty much nails it. Just be sure to follow game1939's directions exactly. He gave you the absolute best way to do it.

Also, I strongly recommend you don't combine different methods - like searching for Top Dead Center, or other methods found in manuals, etc.

Go straight down the line, from front to back, then switch over to the other side of the engine and finish up.

Jake

 

dumb questoin but which one is the intake valve and which one is the exhaust valve?

 

look at your exhaust tubes coming into head, headers make it easy to follow, just find which ports are your exhaust and the others are intake.,
From the front of the head it's EIIEEIIE. This is the same on both sides - (I=Intake, E=Exhaust)
With the valve covers off the rocker that aligns with the exhaust port is the exhaust the other will align with the intake manifold runner this would be your intake

 

hey thanks man i appriciate it

 

no problem

 

I keep seeing people all over the net say to leave hydraulic lifters at 0 lash. I just can't figure out why they go around saying this.

I mean these are real legit engine builders websites too. about as many that say to leave them at 0 say to put them 3/4 of a turn. and a couple has said gm recommends 1 full turn.
I don't know who to belive anymore.

I've always went with 3/4 and it ran just fine.

 

3/4 is the ticket, always works never fails,

 

I will be the one to argue the whole valve lash dispute.

I was asking this same question, and hardly anyone had the same method.

I tried 1 full turn, I tried 3/4, I tried 1/2, and I even tried 1/4 and they all made the engine run like crap.

Until someone finally said that they had a ZZ4 Hydraulic roller camshaft, and they take 0 lash and nothing else, I tried that, and it ran better than it did with any of the other adjustments. So thats what I'll swear by.

Not putting anyone down, just saying my experiences.

 

The cam i have is a hydraulic flat tappet, I'm sure each type of cam takes different methods, Thanks again to everyone posting, we"ll see how it goes, plan on starting it up in the next week or so. Thanks
-tom

 

the cam in my 383 is flat tappet too, the advice i gave you still stands, i could adjust vavles all day and do it the same way i told you....

 

I just finished building my 350 and stuffed it into my 86. I set my initial pre-load at 1/4 turn. My cam is a comp cam, 470 lift, and 270 duration. I'm thinking 3/4 turn on this as well, but again, I am being told to leave it at 1/8-1/4 turn with this lift. What do you guys think? Should I go 3/4 turn?

 

3/4th trust me, i do this everyday or so, always working on chevys, 15 years + in the auto field currently a ase master tech with L-1. this method always works for me, however people do it different ways, I do my car this way is how confident i am in the 3/4. not saying 1/2 or so is wrong just 3/4 always works for me......

 

Cool. Thanks. 3/4 it is. After all the $$$ its gotta be right.