Rocker Arm Adjustment

66 Tiger · Mar 5, 2007

My question is in regards to the amount of resistance that you should FEEL in the push-rod when tightening the rocker?

I'm probably being a bit anal here but there seems to be quite a " grey-area " when adjusting rocker arms.

For instance - the instructions that came with the rockers ( crane ) call for one half to one full turn after starting to " feel " resistance in the push-rod. So I did a 3/4 turn after just barely starting to feel resistence?

When the valves are closed, I'm actually able to twist the rockers back & forth. Is that OK or does that sound a little loose?

Maybe I should have tightened the rockers down after " feeling " a bit more resistance?

Any advice in this matter would be greatly appreciated!

Max Power · Mar 5, 2007

You should feel resistance when all the slack is taken up. The whole point is to have no slack, not feel a precise amount of resistance. Once you no longer have slack and start feeling resistance, than you do your 3/4 turn, or whatever spec you are using.

You're right, you are being a bit anal. The reason there is a "grey-area" with adjusting hydraulics, is because they are designed to have an adjustment range. That's the beauty of hydraulics.

Don't over think it. Find the base circle of the cam, adjust so there is no more up and down slack (or resistance when spinning), then do your spec for turns.

The end.

65Stang200 · Mar 5, 2007

Not to hijack... but... I have got to adjust the valves on a '62 ranchero with a 170-6 (mechanical lifters). What's the best way to adjust those rockers?

D.Hearne · Mar 5, 2007

65Stang200 said:
Not to hijack... but... I have got to adjust the valves on a '62 ranchero with a 170-6 (mechanical lifters). What's the best way to adjust those rockers?

I took this from my 64-70 Motor Repair Manual : With the #1 cylinder at TDC on the compression stroke (this is also when the spark plug fires) the following valves can be set : #1 intake & exhuast, #2 intake, # 3 exhaust, #4 intake, #5 exhaust. Near as I can figure set the lash after running the engine 30 minutes and set the lash to .018-.019" . Then rotate the crank to when #6 cylinder is at TDC on the firing stroke. Then set these valves: #2 exhaust, #3 intake, #4 exhaust, #5 intake, then both intake and exhaust on #6.

SoCalCruising · Mar 6, 2007

The amount of preload on the lifter depends on the lifter. I am one of those who have always heard the 1/2 -3/4 turn instruction, but that much preload leaves my valves hanging open at TDC compression stroke. I learned this when checking cranking compression. I was way down on compression (60-100psi). After resetting the lifters to 1/4 turn preload, compression jumped to 170-180psi. I checked with an engine builder I know and he says they only apply a maximum of 1/4 turn preload on roller lifters and hydraulic roller cams. So, I recommend that you check cranking compression after you adjust the rockers. Pull all of your plugs first to make it easy on your battery/starter.

66 Tiger · Mar 6, 2007

Cool!

Thanks for the replies... This is my first time setting up rockers & I appreciate the advice.

Rocker Arm Adjustment

66 Tiger

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Max Power

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65Stang200

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D.Hearne

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SoCalCruising

66 Tiger

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