push rod slack

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Dec 18, 2011 | 03:59 PM

V8orBUST

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Joined: Mar 2011

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push rod slack

I finally decided to figure out why my 351 was knocking and it looks to be slack in one of the push rods, 1/8"-1/4" play. i replaced the rocker & pushrod but there is still slack, from what i can see without pulling the intake the lifter does not seem collapsed and im reading normal compression on that cyl. any ideas?

Dec 18, 2011 | 04:47 PM

Anafiel

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Joined: Jun 2009

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From: Wagener, SC

Quote:

Originally Posted by V8orBUST

If you've replaced the rocker and pushrod already, then all you have left is either a collapsed lifter, or a wiped cam lobe....seems to me.

Dec 18, 2011 | 06:26 PM

Gary Lewis

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Joined: Jul 2010

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From: Northeast, OK

Quote:

Originally Posted by Anafiel

If you've replaced the rocker and pushrod already, then all you have left is either a collapsed lifter, or a wiped cam lobe....seems to me.

Yep, that's about it - assuming someone didn't put it together with the wrong push rod last time it was apart. But, if the others are fine then that's got to be it.

You can figure out which of the two it is if you have a dial indicator. Put it on the push rod side of the rocker arm and hold down on that side to take all of the slack out. Have someone turn the engine over using a socket on the harmonic balancer's bolt and determine the full lift of the cam lobe. Do the same thing on another cylinder's intake or exhaust, whichever this is, and see if the lift is the same. If so, it must be the lifter. If not, and I suspect it is not, then the cam lobe is bad.

However, all of the above assumes you do not have adjustable rocker arms. The 351W's on these trucks, and I just assumed you have a Windsor, didn't come with adjustable rockers but they can be added. Are the bolts holding the rocker arms tightened down all the way? If so, non-adjustable. But, as I think about it, have you checked the bolt holding the rocker on for the one that has slack?