A little background to start. I'm new to the forum- and slant 6's. Just got a 78 Plymouth Volare, motor seems to be pretty built.

I noticed a little ticking in the top end so I pulled the valve cover to inspect. I found TD 1.50 ratio rocker arms.

What I noticed is my cyl 4 rocker arms have excessive play back and forth(sliding towards the front and rear of the engine on the rocker shaft). A feeler guage tells me I have just over 1mm of play. Cyl 3 also has some play, around half a mm. The rest of them seem nice and sturdy.

I was thinking it was either an issue with the rocker shaft retainers or the composite spacers in between the rocker arms, but neither show any signs of excessive wear.


After some searching on here I found a post that mentioned that the center rockershaft retainer is supposed to be longer than all the others(which sits in between the 2 pairs of rockers I'm having play in). My engine has the one longer retainer all the way in the front of the engine.

So my question becomes, does this longer retainer actually belong in between the center? If so, it is longer on one side than the other- which way does it go in?
In case that is not my issue- do factory slant 6's have those composite spacers? Or are those specific to these aftermarket arms?
Sorry for the long winded post, but I wanted to be specific. Thanks in advance!

Welcome to the board! There really is no set in stone pattern, but the rockers need to be spaced/shimmed so the tips are centered on the valves. It does appear that you need a longer spacer in the middle, I can see the rockers are too close to the center of the head.

Stock rockers were centered with the hold downs, but you could get shim kits from Mancini or Mopar Performance to correct as needed.

If that is a street car keep an eye on the valve stems. I do not know if T&D corrected the issue but some roller rockers do not oil well and will beat up the valve stems.

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Official Cookie and Mater Tormentor.

Thanks for the welcome, and the information! I took another look at it today, and with the info you gave me I believe I can swap a few of the hold downs around and end up with my rockers all centered on the valve stems. I'll be testing that theory this weekend.

I checked out the stems and none show signs of abnormal wear, so far so good- but I will certainly be keeping my eye on it as I plan to pretty much daily drive the car once the winter is over.