Push Rod Length - does size matter?

[Big Daddy 70]

OK - so I had a noisy lifter last week. I took the valve cover off, and found one lifter pretty loose. I tightened it down till it stopped making noise, and plus 1/4 turn. Ran it for several days, no issues.

Monday it started to get noisy again. Pulled the cover off last night, found the same lifter loose. Removed the lifter, inspected the push rod, and found the top to be broken. I got the new one today, but it appears to be about 1/4 to 3/8 longer than the old one.

Will the length make a difference? There is plenty of stud available for adjustment up, so I am thinking it will not may not matter. I've never replacec one before, but it looks pretty straight forward.



Thanks!

[GASoline71]

I would be concerned of why the rocker arm was loose to begin with. Is the stud coming out of the head? Maybe the locknut back off? Pull the lifter out of the bore to see if it's being eaten by the camshaft?

Gary

[Big Daddy 70]

The stud is tight. The cam side looks perfect.

I think what might have happened is that the push rod may have gotten damaged in the first place, causing it to go out of adjustment. When I readjusted it, the tip broke. I was not smart enough to inspect the push rod the first time. Here are a few photos. You'll notice even the push rods are a little different design on the ends.

[jocko]

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.

[jocko]

Ah - and now that i look at your push rod pics - compare your new one to an existing GOOD one - they are probably the same length and good to go.

[Big Daddy 70]

Yes - ROCKER was what I meant to say in my previous post.

Well, a story is unfolding here. I pulled the rocker from the intake side - looks fine. I pulled the next exhaust rocker - and take a look at that one. (2nd and 3rd picture)

First, for measurement sake - my new one is the correct size. However, this one is blasted too! (see picure #2) Plus a little damage to the rocker (picture 3). I guess this may have become a little bigger job than first anticipated.

Should I go deeper into and pull the lifters and inspect them? I've never done these before - am I getting into the weeds here? I guess I need to pull out the Chiltons :-)