“Original” Recommended

602/604 Valve Adjustment

Questions or Problems contact us at: Ph.: 330-540-7223 or email brad@race-1.com

(all information below is a recommendation from Race-1 not necessarily from GM)



**Positioning of the valve for adjustment**

When the intake valve is closing—Adjust the Exhaust

When the exhaust valve just begins to open—Adjust the Intake

There are other methods but we have found this to work on all engines and leaves less room for mistakes.

**NOTE** If you follow the firing order you will only have to turn the crank ¼ turn between valves once you get #1 in position.




Roll the pushrod between your finger and thumb as if it were a cigar.


At the same time begin tightening the adjuster nut.


The INSTANT that you feel an increase in resistance to roll the pushrodSTOPthat is zero lash.


NOTE this does require a certain amount of “feel.”

By the time you finish your first set you will be a pro!


Next: tighten the adjuster nut ½ to ¾ turn more.


Next: tighten the set screw (Allen)


Next: with your hex key (Allen wrench) and your 5/8” wrench turn both into the stud another 1/16 to 1/8 turn.

This secures the set screw from backing out.

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