Been a while guys. Im building my 396 with a hydraulic cam, lifters and roller rockers.The book say tighten until pushrod barely spins then 1 full turn. I did this and the valves are held open? Is this normal with all new stuff. Im hoping so and the oil and lifters will pump and allow clearance? Im looking through spark plug holes and valves are held open quite a bit. Thanks in advance for any input.

The lifters have to be on the base circle of the cam when you adjust them.Start with number 1 cylinder rotate the engine until the exhaust valve just starts to open adjust intake.After you adjust intake rotate engine until intake opens then just starts to close adjust exhaust.Now you only have 7 more to do! graemlins/waving.gif

These are for both roller & flat tappet.
Easiest way & very accurate for a hyd cam.
Bring the engine up on number 1 TDC firing.
Back off the rockers on that cylinder (#1) & tighten them til the pushrod is just getting hard to rotate.
I give them about 1/4 turn in. You can go to 1/2 but I like to run them close to the top of the lifter.
rotate the engine 90 degrees (1/4 turn) & go to # 8 & adj it the same way, then 4, 3, 6, 5, 7, 2 going 90 degrees per cylinder.
If you have a good damper it will be marked at 90 degree increments. Otherwise just use your breaker bar or ratchet & turn it 1/4 turn per cylinder.
Pulling the plugs makes it much easier to turn.
This is the way I adjust valves when I assemble an engine.

With a solid I always recheck by the second method after getting it running & broke in.
With a hyd it really isn't necessary unless you have a loose one.

Method two:
With a solid I use the ex open intake close method which you can use also.
With a starter button or helper crank the engine until the exhaust valve just starts to open & adjust the intake.
You can turn it by hand if you need the excerise :D
Crank again until the intake valve is closing & adjust the exhaust.
This is the correct way to adjust valves with a performance cam, especially solids as it assures you you are on the base circle.

So then 1 turn is too much? it looks like its holding the valve open on the stand.

Hyd lifters are designed to operate with a certin amount of preload.Regardless of number of turns most hyd lifters are designed to operate with a preload range of between .020 and .060.IE the pushrod seat should move down somewhere between those two numbers.

Throughout the decades not all lifters were made the same.Back in the 70's some AC lifters had very long amounts of travel and could one could turn the adj nut as much as 3 turns....Other lifters can barely tolerate 3/4 of a turn.

The turn numbers you see depends on the rocker stud diameter and thread pitch and rocker ratio.A shaft type rocker with the adjuster operating directly on the pushrod wont have any multiplying effect of the rocker ratio and would require a totally different amount of turns...Ultimately turns dont matter as much as depressing the pushrod seat the correct amount because that it what the lifter actually responds to.

It;s just not real easy to see and measure this without the engine on a stand and the intake manifold off. graemlins/clonk.gif

Since the subject is up I have a question. I adjusted valves using EOIC and after adding 1/4 preload some rockers upon rotation become very tight. Actually 4 at a time are tight on each 90 degree rotation. While the others seem still loose. Add another 1/4 turn? Readjust again? I've been thru this adjustment three times to make sure it is right. I don't want to wipe a cam on startup. :confused:

OK I dont mind doing it again .I do have the engine on a stand and intake is off ect.The studs are stock.The way it is though I doubt it will have compression if the valves are held open?

DS,

Are ALL the valves being held open ALL the time?

If so, you do have a problem. I'd suggest that you back all of them off completely and start the adjustment process from scratch, using the procedure mentioned above. Tighten until all up and down play of the push rod is eliminated, but NOT enough to depress the seat in the lifter. Then give the nut 1/4 to 1/2 of a turn.

Dan

After reading the edelbrock info it does say 1/4 turn

I have been a technician for the past 30 years and have heard the same thing for years, "should I go 1/4, 1/2, 1 full turn"

1/4 is the standard but with the way parts are being made today, it's a crap shoot.


I am running a Lunati 540/550 lift cam in ny 71 el camino SS 402 (406), I have installed 2 sets of lifters and went to roller tip rockers, the rockers I bought were CRAP, The MELLING Lifters came apart.

I went back to stock stampted rockers, and another set of Melling Lifters.

I still have a noise between shifts (tapping).

The engine is comming out and visually inspected,
Heads are being fitted with new Lunati springs to 640 lift and titainium retainers , Hardened seats, New Stainless Valves, going with Lunati lifters, (matched for the cam) Or mabey a Solid
lift cam?

What I am tring to acheive is a car that will run in the 10's and still be able to get 20mpg :D ;)

DS one thing to add...loosen the rocker arm and spin the push rod with your fingers. it will spin easily,as you tighten the rocker you will reach a point where it just starts to have alittle drag on it..this is zero lash,(not where you can barely spin it).Then turn your nut down farther.some times with new lifters it is possible to go too far. The most important thing about making a new cam last is the breakin period. Make sure you have it lubed up good and when you start the engine for the first time with a new cam dont let it idle.Keep the rpms up to around 2000. A lot of idle time on a new cam will kill it..Steve B