I have a 471 Hemi with alum heads and a hydraulic cam. I have been hearing what sounds like a lifter or valve train tick back in the #5 or 7 cylinder area. I just did a compression test and came up with this:

#1 - 190 : 190 - #2
#3 - 190 : 190 - #4
#5 - 190 : 195 - #6
#7 - 175 : 185 - #8

So I pulled the driver side valve cover, major PITA with power brakes

Nothing looks terribly loose or out of wack. You can push down slightly on the lifter to cause it to be loose but I am guessing that is just the hydraulic part. I have messed with hydraulic in a long time as my other motor is solid roller, way easier to adjust. Always seems like I am guessing on hydraulic, any tips.

Plugs are also looking rich, but strangely the #7 that is low on compression is one of the better looking plugs.

This is the simplest and the most accurate method taught to me 40 years ago. it has never failed me.
A remote starter switch will be very helpful for this process

Hydraulic lifters can be set, hot or cold, pumped up or not using this procedure. It will also work for an initial set up on a solid lifter motor.

For Hydraulics, most manufacturers want .020-.040 preload. If you have a 3-8 x 24 adjuster, 1” divided by 24 TPI = .0416” so 1/2 turn beyond zero lash, will = .020 , 3/4 turn will = .030.

I like to start at the LF corner of the motor. (exhaust) Turn the engine over in the direction of rotation until the intake valve for that cylinder is almost closed. You can now adjust the exhaust valve for that cylinder.

Loosen the adjusting nut until the pushrod spins freely between your finger tips. While spinning the pushrod slowly tighten the adjusting screw, when you find zero lash your will feel a definite change in resistance to spinning the pushrod. You may want to repeat this a few times to get the “feel”. Once zero lash is found, add 1/2 to 3/4 of a turn and lock the adjuster.

Move to the next valve in line (intake). Rotate the motor in the direction of rotation until the exhaust valve for that cylinder just begins to open. Repeat the above adjustment procedure.

Repeat the process for the remaining cylinders.

Summary:

Adjust the exhaust as the Intake is almost closed

Adjust the intake as the exhaust just starts to open

Thanks, that is the same way I do my solid cam. For me the hard part is feeling that "0" lash to know when to do the 3/4 of a turn.

Could be an exhaust manifold leak? The compression test has all cylinders within 10%. Is the spec <10%? I forget.

Should he take into consideration that he has Aluminum heads which grow more, and need a little more preload?

Ok I readjusted the Drive side bank. Feels like they are had about 1/4 turn of preload on them except exhaust on #7 was at about "0"

Here are my compressions now

Before : After
#1 190 : 180
#3 190 : 180
#5 190 : 180
#7 175 : 175

So should I be worried about loosing 10# on 1-3, makes is sound like they are too tight?

I'm not sure but are they quiet now?

I wouldn't trust a comp test until after I had run it and the lifters had a chance to settle in with the new adjustments. Right now you do not know if number 7 was mis-adjusted to begin with or if you have more serious problems afoot. Pulling that lifter is the only way to know now.

Compression tests should always be done warm to get the most accurate readings.

I would keep good notes on your findings and recheck #7 after 500 or so miles. If it loosens up again it could be an indication of the camshaft going away. hopefully not

Another option would be to mount a dial indicator and check your lift comparing the readings between cylinders. Again this should be done on a warm motor to make sure the lifters are pumped up. IF a lobe is wearing it will show less lift. I would start with number 7 as that is the suspect cylinder.

I rechecked them again as I forgot to hook up the battery charger this time like I did last time. Now I get these numbers, look better

Before : After
#1 190 : 185
#3 190 : 185
#5 190 : 185
#7 175 : 180

Think I will pull the other side apart and check them while I am at it.

FYI ,I have also experienced random ticking noise on hemis from rocker arm adjusters hitting the splash shield on the underside of the valve cover as well as exhaust valve springs/retainers just barely hitting the inside of the valve cover

Just wanted to update that I got them all adjusted and really it sounds about the same, maybe just the way they sound?

Might be all in my head but it seems to idle a little rougher then it did, but it had been awhile since I had it running so just going off memory.

I ended up tightening all the rockers about 1/4 turn. It does need new plugs but put it away for the winter now.

Yes Aluminum heads hot and cold will generally have a significant lash difference. I have to set my solid roller approx .006-.010" tighter to have the hot lash correct.

I agree slightly more preload on those big aly heads, my motor grew .009 thou when hot!