Valve adjustment

Valve adjustment

Postby 69roadrunner [OP] » October 15th 2019, 3:48am

Moving forward with my cam replacement. The '98 FSM says to adjust the rocker arms with the following procedure:

"Rotate the crankshaft balancer to position the crankshaft balancer timing mark 57-63 degrees clockwise or counterclockwise from the engine front cover alignment tab. Tighten the valve rocker arm nuts to 25 Nm (18 lb ft)."

There are two marks but the illustration indicates the correct starting position is where one mark aligns with the front alignment tab and the other aligns with an index on the lower aspect of the timing cover. It doesn't mention whether the timing should start at TDC #1 but I would assume so. Then, rotate forward or backward 57-63 degrees and tighten them all down to 18??? Doesn't make sense. Are those two positions where the lifter rollers are on the base circle of the cam and all the valves are closed??? I wouldn't think so.

I saw a post by AstroWill on adjusting the valves differently but maybe that was an earlier model year??
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Re: Valve adjustment

Postby paulo57509 » October 17th 2019, 10:52am

I don't have a '98 FSM in front of me, but I believe that you're misinterpreting what is being stated in your FSM; you're reading too much into it.

Since the rocker arm nuts are tightened down to 18 ft-lb, there is no "typical" valve adjustment going on.

Proceed by rotating the crankshaft until the timing mark on the damper lines up with the timing tab referenced in the FSM (I don't know why it instructs you to do this, but just do it), lube up the rockers and balls, install the pushrods, rocker arms/balls/nuts and torque the nuts to spec. Then you're done.

Being on TDC #1 compression, base circle, etc. doesn't come into play here.
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