Thread: Setting valve lash on a 383 with a hydraulic cam

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Originally Posted by DennyW

Sorry guys, but I just have to add my 2 cents.

Most all light lift .500 and under cams that I have worked on, if you get both valves closed, and piston on TDC, there is not a problem at all doing both at that time, because of the base circle, and ramp location.

Now, of course, if your running a .700 lift roller cam, we are in a different ball park, but I really doubt the guy has that. Do you ? You didn't say what size cam ?

On a smaller cam, you have about 224º + - of base circle. If you check this out, you will find that if both valves are closed, and the piston for that cylinder is at TDC, they both will still be on the base circle. And, with the hydraulic flat tappets, since the adjustment can be from 1/4 turn to 3/4 turn on average, the valve adjustment will be good. Now, just so you know, I have double checked this in the past, by doing the engine running adjustment to double check this, and they were on the money.

Here are 3 of the biggies saying the proper way, and they are a little different, but pretty close.




Comp cams:

4. Adjusting preload: Turn the engine in the normal direction of rotation. Start with cylinder
number one (1). When the exhaust valve begins to move, adjust the intake valve to the correct
preload. To reach zero, take the push rod between your finger tips and move it up and down
while you tighten down the rocker arm. Once you feel no more vertical slack, you are at zero
preload. Make sure the push rod is in the lifter and the rocker arm seat when making valve
adjustments. As stated before the best setting is zero to 1/8 of a turn. Now, you can move on to
the exhaust valve on the same cylinder. Next, rotate the engine over again until the intake valve
reaches maximum lift and is almost all the way back down. Then set the exhaust valve using
the same method as the intake (zero to 1/8 of a turn). Continue adjusting the valves on each
cylinder in this manner until all valves are adjusted.

Lunati:

On hydraulic lifter cams, rotate the engine in the normal direction of rotation until the exhaust valve begins to open. At this point, adjust the intake valve to ZERO LASH with no pre-load at the lifter, then tighten 1/2 more turn. Rotate the engine again until the intake valve has fully opened. Now you can adjust the exhaust valve to ZERO LASH, then 1/2 more turn. Repeat this procedure until each cylinder is completed.

Crane:

Adjusting Hydraulic Lifters for Proper Preload
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 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 push rod. Wait a minute or two for that hydraulic lifter to return to a neutral position. The spring inside the lifter will move the push rod 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 push rod with your fingers while tightening down the rocker arm. When you feel a slight resistance to the turning of the push rod, 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.

Denny,what you have said is true.
I think I.M.O. it is a very bad habit to try and take any "short cuts" when adjusting lash.
I don't whant some "new guy" to engine building think he can do this on every build.

Originally Posted by DennyW

I agree with the proper procedure. That's why I also posted the others. I wouldn't call what I said as a bad habit though. It's just that with the smaller cams, you can adjust them the way I said. Like anything else, you have different adjustments, and ways to do them, and get the same results for that particular engine. That's all I was trying to say on that Erik. Theres no difference adjusting them with the engine off, or on, but, as some guys say you can't do that, the engine has to be running to set them correctly, which as you know, is not true.

O.K,maybe bad habit was not the correct choice for words.
Like you said the engine does not have to be running.

The absolute best way is to set them with the intake off,when first assembling the engine.You want the pushrod to engage the plunger of the lifter past the circlip retainer in the lifter body.
This is how I did mine, rotate untill lifter is on base circle,install pushrod ,rocker and then adjust them until the lifter internals are depressed below the circlip inside of the lifter body,I also used blue loctite on the poly locks.
I then assembled the engine and broke it in,no further adjustments needed,looking back I would not hesitate to use red loctite on the poly locks.
For a hydrauilic lifter in a mild engine ,you should never have to adjust them again ,unless there is failure going on,they should never loose the adjustment in 100,000 miles,unless wear /breakage/stud pulling out of the head ,etc.
Unfortunatly this only works on mild hydro cams and only on the initial assembly of the engine,I would not use this method on a installed engine,only a fresh engine stand build.