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Discussion Starter #1
I've run into this several times this year as to what some companies have preached as to "How to adjust hydraulic roller lifters". Well we have had a couple board members chase some rpm issues due to improper adjustment of the Morels. This is direct from Morels website and if the mods so choose can be a sticky.

Installing and Adjusting Morel Hydraulic Lifters:
1. Do not wash in any solvent. Wipe the parts off with a lint free towel.
2. Use 10W30 oil and lube the O.D. of the body and wheel.
3. Make sure the lifter-to-bore clearance on cast iron blocks is: .0015” - .0017”.
On aluminum blocks that oil the lifter (LS Series), the clearance is: .0012” - .0014”.
Both of these measurements are at 70 Deg F.
The aluminum block will have a higher rate of expansion and that is why the
clearance is tighter.
Adjusting the Zero-lash setting of the Lifter:
1. I always like using the firing order to set the valves. Put the engine on #1 cylinder.
2. What we want is the int. and exh. to be on the base circle of the camshaft.
3. Adjust the rocker until the push rod just starts to get tight while taking the pushrod
and rolling it between your thumb and finger. Once you feel drag, this is what we call
4. You are now ready to tighten down on the adjuster using the following method:
a. It is important to know the thread pitch, in threads per inch, of the adjuster
nut, because one complete turn of the nut will move a distance of one
complete thread. Therefore, verify the thread pitch of the adjuster nut,
because racing rocker manufacturers use different nut sizes and thread
b. If your adjuster nut is 7/16 x 20 threads per inch, then divide 1 inch by 20
threads per inch. One complete turn down on a 7/16 by 20 adjuster nut will
move .050".
c. Next, divide .050" divide by 4 to calculate the distance for a quarter-turn of
the adjuster nut (.050" / 4 = .0125").
d. For a 3/8 x 24 adjuster nut, the calculations are:
1" / 24 TPI = .042" per full turn and .042" / 4 = .0105" per quarter-turn.
e. Use the chart below to determine how many quarter-turns to tighten the
adjuster nut after Zero-lash:
Cast Iron block and Cast Iron Head = .020" - .025"
Cast Iron block and Aluminum Head = .030" - .035"
Aluminum block and Aluminum Head = .045" - .050"
5. Repeat these adjustments for each cylinder running through the firing order

Premium Member
1,151 Posts
Great info Chris. Just out of curiosity, is there a difference between adjusting the Morel's and other brands of hydraulic lifters? I thought that you adjust all hydraulic lifters the same with the only argument being how much of a turn down past zero lash.

Premium Member
8,375 Posts
Yikes! Might as well run solids. Very little math needed to operate a feeler gauge.
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