Chevy Corvette Forum banner

1 - 20 of 28 Posts

·
Registered
Joined
·
79 Posts
Discussion Starter #1
Had the valve covers off while changing out injectors and thought I might adjust the valves.
There are so many methods of doing this, but which one is correct. I don't want to do it with the engine running, since I have detailed my engine and with my luck I would drop something into the running engine.
To get to zero lash, should I back the nut off until the rocker is loose and then set to zero lash and then add an additional 1/2 to 1 full turn of the nut?
Any help appreciated.
 

·
Registered
Joined
·
836 Posts
Valves?

Had the valve covers off while changing out injectors and thought I might adjust the valves.
There are so many methods of doing this, but which one is correct. I don't want to do it with the engine running, since I have detailed my engine and with my luck I would drop something into the running engine.
To get to zero lash, should I back the nut off until the rocker is loose and then set to zero lash and then add an additional 1/2 to 1 full turn of the nut?
Any help appreciated.
Their Hyd ? 1/2 turn is enough ....
 

·
Registered
Joined
·
1,489 Posts
Had the valve covers off while changing out injectors and thought I might adjust the valves.
There are so many methods of doing this, but which one is correct. I don't want to do it with the engine running, since I have detailed my engine and with my luck I would drop something into the running engine.
To get to zero lash, should I back the nut off until the rocker is loose and then set to zero lash and then add an additional 1/2 to 1 full turn of the nut?
Any help appreciated.
Yes, but be sure the lifter is on the heel,the base circle of the lobe for each valve before you start.

RACE ON!!!
JIM
 

·
Registered
Joined
·
1,466 Posts
ADJUST HYDRAULIC LIFTERS
From Crankshaft Coalition Wiki
Jump to: navigation, search
The following is based on instructions originally by Crane Cams:

You will want to know the firing order of the engine you are working on. The Chevrolet small block V8 (aka"SBC") is: 1-8-4-3-6-5-7-2
You will want to know what direction the distributor rotates. For the SBC, it is CW.
And you will want to know the order of the valves as they are located in the cylinder head. The small block Chevy V8 is: E I I E E I I E
[edit] Adjusting Hydraulic Lifters for Proper Preload
EO/IC Method (Exhaust Opening/Intake Closing)

In order to adjust the preload, the lifter must be properly located on the base circle or "Heel" of the lobe.

At this position the valve is closed and there is no lift taking place. You will need to watch the movement of the valves to determine which lifter is properly positioned for adjusting.

1. Remove the valve covers, and pick a cylinder that you are going to set the preload on.

2. Hand rotate the engine in its normal direction of rotation and watch the exhaust valve on that particular cylinder. When the exhaust valve begins to open, stop and adjust that cylinder's intake rocker arm. (Why? Because when the exhaust valve is just beginning to open, the intake lifter will be on the base circle of the lobe- the correct position for adjusting the intake.)

3. Back off the intake rocker arm adjuster and remove any tension from the pushrod. Wait a minute or two for that hydraulic lifter to return to a neutral position. The spring inside the lifter will move the pushrod seat up against the retaining lock if you give it time to do so. (If you are installing brand new lifters they will be in the neutral position when they come in the box.)

4. Now spin the intake pushrod with your fingers while tightening down the rocker arm. (If you are uncertain that you are feeling the "Zero" setting, jiggling the push rod up and down will sometimes give a better sense of when all the clearance has been removed.) When you feel a slight resistance to the turning of the pushrod, you are at "Zero Lash". Turn the adjusting nut down one half to one full turn from that point. Lock the adjuster into position. The intake is now adjusted properly.

5. Continue to hand turn the engine, watching that same intake. It will go to full open and then begin to close.When it is almost closed, stop and adjust the exhaust rocker arm on that particular cylinder. (Again, when we see the intake almost closed, we are sure that exhaust lifter is on the base circle of the lobe.) Loosen the exhaust rocker arm and follow the same procedure described before in steps 3 and 4 to adjust this rocker arm.

6. Both valves on this cylinder are now adjusted, and you can move on to your next cylinder and follow the same procedure again.
 

·
Registered
Joined
·
79 Posts
Discussion Starter #5
Thanks guys, I can spin most of the pushrods with my fingers freely when each cylinder is at TDC on the compression stroke. Sounds like they need a little adjustment.
Workshop manual (haynes) says 1 full turn after reaching zero lash, I was going to go 1/2 turn, so I don't bind anything up
 

·
Registered
Joined
·
9,695 Posts
Thanks guys, I can spin most of the pushrods with my fingers freely when each cylinder is at TDC on the compression stroke. Sounds like they need a little adjustment.
Workshop manual (haynes) says 1 full turn after reaching zero lash, I was going to go 1/2 turn, so I don't bind anything up

They SHOULD turn when that cylinder is at TDC. Most people adjust their rockers by turning the adjustment nut down 1/2 to 3/4 turn but 1 turn doesn't hurt anything IF the lifter can stand that much. Most stock lifters will easily accept 1 turn but my Speed-Pro hydraulic roller lifters can't. So I have to adjust them only 1/2 turn.
 

·
Registered
Joined
·
39 Posts
Valve Adjustment

Hi,
GM says to do them while the engine is running, but that's messy. Adjustment is as follows below. The lifter must be on the heal of the lobe to get an accurate adjustment, to accomplish this you split the firing order, 1843 6572 now with #1 Int, at full lift, #6 Int. lifter is on the heal of the lobe ready for adjustment. When your tightening the nut for the initial contact, hold the push-rod with your thumb & for finger & move the push-rod up & down instead of rolling it, it's more accurate. After all up & down movement is gone you need to go 3/4 of a turn further, this is don to put the plunger in the center of it's travel inside the lifter. (do the 3/4 turn a 1/4 turn at a time slowly)
Rich

#1 cylinder Intake Valve at full valve lift .... Adjust #6 Intake Valve
#8 cylinder Intake Valve at full valve lift .... Adjust #5 Intake Valve
#4 cylinder Intake Valve at full valve lift .... Adjust #7 Intake Valve
#3 cylinder Intake Valve at full valve lift .... Adjust #2 Intake Valve
#6 cylinder Intake Valve at full valve lift .... Adjust #1 Intake Valve
#5 cylinder Intake Valve at full valve lift .... Adjust #8 Intake Valve
#7 cylinder Intake Valve at full valve lift .... Adjust #4 Intake Valve
#2 cylinder Intake Valve at full valve lift .... Adjust #3 Intake Valve
now the exhaust
#1 cylinder Exhaust Valve at full valve lift .... Adjust #6 Exhaust Valve
#8 cylinder Exhaust Valve at full valve lift .... Adjust #5 Exhaust Valve
#4 cylinder Exhaust Valve at full valve lift .... Adjust #7 Exhaust Valve
#3 cylinder Exhaust Valve at full valve lift .... Adjust #2 Exhaust Valve
#6 cylinder Exhaust Valve at full valve lift .... Adjust #1 Exhaust Valve
#5 cylinder Exhaust Valve at full valve lift .... Adjust #8 Exhaust Valve
#7 cylinder Exhaust Valve at full valve lift .... Adjust #4 Exhaust Valve
#2 cylinder Exhaust Valve at full valve lift .... Adjust #3 Exhaust Valve
 

·
Registered
Joined
·
5,563 Posts
Hi,
GM says to do them while the engine is running, but that's messy.
you use clips made to keep the oil from spraying
it's not that messy
 

·
Registered
Joined
·
1,466 Posts
I always do it running also, very quick and easy to do and if done quickly not that messy..........I just put throwaway towels arround the heads to catch oil.
 

·
Registered
Joined
·
5,563 Posts
me too...if you dont want to spread your engine with engine oil...this is the way to go
[/URL][/IMG]
nice idea but how do you get the clips on the pushrod end of the rocker ?
they squirt all over w/o clips
 

·
Registered
Joined
·
9,695 Posts
I have always adjusted mine at TDC with the engine cold and not running. My stock lifters could be set at 1 full turn but my present Speed Pro roller lifters will only accept 1/2 turn. The only way you can prevent hydraulic lifters from "pumping up" is to set them with several thousands of clearance with a feeler gauge. But when you do that you also screw up the geometry and cause increased side-loading on your valve guides. But the hydraulic lifters made in the last 30 years will usually go well over 6000 rpm without pumping up as they use a different valving system under the plunger then the lifters used in the 50's and 60's.
 

·
Registered
Joined
·
300 Posts
Hi,
GM says to do them while the engine is running, but that's messy. Adjustment is as follows below. The lifter must be on the heal of the lobe to get an accurate adjustment, to accomplish this you split the firing order, 1843 6572 now with #1 Int, at full lift, #6 Int. lifter is on the heal of the lobe ready for adjustment. When your tightening the nut for the initial contact, hold the push-rod with your thumb & for finger & move the push-rod up & down instead of rolling it, it's more accurate. After all up & down movement is gone you need to go 3/4 of a turn further, this is don to put the plunger in the center of it's travel inside the lifter. (do the 3/4 turn a 1/4 turn at a time slowly)
Rich

#1 cylinder Intake Valve at full valve lift .... Adjust #6 Intake Valve
#8 cylinder Intake Valve at full valve lift .... Adjust #5 Intake Valve
#4 cylinder Intake Valve at full valve lift .... Adjust #7 Intake Valve
#3 cylinder Intake Valve at full valve lift .... Adjust #2 Intake Valve
#6 cylinder Intake Valve at full valve lift .... Adjust #1 Intake Valve
#5 cylinder Intake Valve at full valve lift .... Adjust #8 Intake Valve
#7 cylinder Intake Valve at full valve lift .... Adjust #4 Intake Valve
#2 cylinder Intake Valve at full valve lift .... Adjust #3 Intake Valve
now the exhaust
#1 cylinder Exhaust Valve at full valve lift .... Adjust #6 Exhaust Valve
#8 cylinder Exhaust Valve at full valve lift .... Adjust #5 Exhaust Valve
#4 cylinder Exhaust Valve at full valve lift .... Adjust #7 Exhaust Valve
#3 cylinder Exhaust Valve at full valve lift .... Adjust #2 Exhaust Valve
#6 cylinder Exhaust Valve at full valve lift .... Adjust #1 Exhaust Valve
#5 cylinder Exhaust Valve at full valve lift .... Adjust #8 Exhaust Valve
#7 cylinder Exhaust Valve at full valve lift .... Adjust #4 Exhaust Valve
#2 cylinder Exhaust Valve at full valve lift .... Adjust #3 Exhaust Valve
Nicely done :thumbsup3:
 
1 - 20 of 28 Posts
Top