The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Push Rod Length

**jocko** · 05-30-2012, 05:14 PM

yes, size (length) matters...

If you use the rocker stud bolt to compensate for a too-long push rod, you will jack up the geometry - likely resulting in premature rocker tip (on the valve end of the fulcrum) wear.

Need to buy stock length push rod and take a current (good) one with you to verify when you pick it up.

As for what's going on here - I'd pull the actual lifter out of it's bore above the cam and inspect for wear/damage. If it's good (and the cam lobe looks ok through the lifter bore with a bright light) I'd just install the proper pushrod, and see what happens. Likely that the gacked up push rod is what was causing the loose rocker to develop as the top end of the pushrod slowly ate itself.

If you DO have lifter (not rocker, just to keep the termninology straight - what you called a lifter in your 1st post is actually a rocker) damage, then all bets are off, cam's probably damaged also and both need to be replaced. But I doubt that is the issue - am guessing you had a blocked oil passage in the pushrod and the rocker (lifter side) tip did not get lubed and ate itself. Resulting in a shorter, damaged pushrod - and the resultant apparent loosening of the rocker nut - in actuality, the pushrod was just shortening slightly making the rocker appear loose.

05-30-2012, 05:14 PM	#4
jocko Senior Member Join Date: Oct 2009 Location: Godley, TX Posts: 18,001	Re: Push Rod Length - does size matter? yes, size (length) matters... If you use the rocker stud bolt to compensate for a too-long push rod, you will jack up the geometry - likely resulting in premature rocker tip (on the valve end of the fulcrum) wear. Need to buy stock length push rod and take a current (good) one with you to verify when you pick it up. As for what's going on here - I'd pull the actual lifter out of it's bore above the cam and inspect for wear/damage. If it's good (and the cam lobe looks ok through the lifter bore with a bright light) I'd just install the proper pushrod, and see what happens. Likely that the gacked up push rod is what was causing the loose rocker to develop as the top end of the pushrod slowly ate itself. If you DO have lifter (not rocker, just to keep the termninology straight - what you called a lifter in your 1st post is actually a rocker) damage, then all bets are off, cam's probably damaged also and both need to be replaced. But I doubt that is the issue - am guessing you had a blocked oil passage in the pushrod and the rocker (lifter side) tip did not get lubed and ate itself. Resulting in a shorter, damaged pushrod - and the resultant apparent loosening of the rocker nut - in actuality, the pushrod was just shortening slightly making the rocker appear loose.