Has anyone successfully used spacers on the rocker arm shaft to better align the rocker arms over the valves/pushrods and eliminate some of the "wiggle room" that is inherent with the Slant 6 valvetrain?

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Rob

I’m Mater
The Kentucky Poser

Selectiong and positioning the shaft hold downs to center each rocker arm helps alot:





If there is excess 'looseness' between the arms, then you can use a stack of cut-down spacers... (the hard way)
http://www.dutra.org/dutraorg/pictures/ ... er-cut.jpg

Or bend the spacer a little to take-up the slop.
DD

Thanks Doc!

You always have the answer (with detailed photos) seemingly right at your fingertips!

I really need to start building up my "parts stash"...

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Rob

I’m Mater
The Kentucky Poser

Great info.

While doing a "non running" valve adjustment there is so much movement, I get a different gap each time. Is this "wiggle room" inherent on all /6 rocker shafts or were there any changes made with the later models? Wear issue?

thanks!

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Super Six Conversion Stromberg

I've also positioned the spacers and found thin washers at the local hardware store as shims too.

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11.02 @ 120.56
http://www.youtube.com/watch?v=EAxRmoDgsdY
Chassis dyno
http://www.youtube.com/watch?v=wd6hFGzLJMc

MP used to sell shim kits.

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Official Cookie and Mater Tormentor.

I wander if the shafts are the same size as the big Block Mopars, or maybe close enough to work? They do sale shimes and spacers for the BB engines. 440 Source would be a good place to get the BB shims if they work. I could measure some here later and find out but it might be a couple days before I can get in the basement.

A interesting part I found when looking for these shims was a set of shaft shims for raising the shafts for the BB engines. Moving the shaft up or down gets into a can of worms as far as rocker geometry is conserned, but it could be a cheap way to gain some clearance for guys with shaved heads and blocks ( instead of having to buy shorter pushrods). These where also at 440 Source.


I havnt been well lately or I could check the usability of these out. BUt I can still measure the shafts and find out if they can even fit if someone doesnt already know.

As far as rocker geometry there is a term called "Mid-Lift" that is envolved with setting up rocker arm geometry. You can read about this at Mid-Lift.com ( Millers Rockers) and learn about setting the proper Rocker height. I have wandered, although not been able to test, that this might have something to do with our rockers not getting the right amount of ratio on our engines. WHen I did measure one of my engines I only got a reading of 1.4 to 1 ratio and I believe our rockers are listed as 1.5 to 1.

I did this on a engine, which is not reallly how to do it (measure rocker ratio), becuase of pushrod flex, lash and even other parts that can have give in them. BUt still I felt there was a lot of lose of ratio found and I didnt feel all of it was due to looses in movement. Rocker height, excess movement, plus even tip geometery could effect the ratio.


Jess

http://www.mcmaster.com/#shims-and-shim-stock/=bny52t

McMaster-Carr, they're called machine bushings, or shims.

Roger

OK, I've there, done that, & will relate what NOT to do since I broke some stuff just trying to "wing it". If you want to "tighten up" the side-slop on the rocker arms, you need HARDENED steel round shims - mild steel will be ground to dust. Leave some clearance (0.020"?) to allow for heat expansion of the rockers.

Any time you you make a significant change to head/cam/ valves/ springs you need to check (&adjust) your rocker geometry. The valve moves up/down in a straight line, the rocker tip in an arc. So the rocker-to-valve contact point moves across the valve tip as it goes full open to full closed.

At 1/2 lift you want the contact point centered on the valve. If it's not then you can end up with side load on the valve & possibly rapid valve guide wear. (that stunk- a couple valves stuck open just enough to bend 2 pushrods)

If contact point isn't centered then it can usually be corrected by raising the the rocker shaft with shims. BE CAREFUL!! On my first attempt I cut 0.040" sheet metal squares, drilled holes , bent them to shape around a shaft & installed them. I was close but needed a little more, so tried 0.050". right? - WRONG! As I tightened the rocker mount bolts to spec one felt a little strange- "mushy" but not stripped. It turned out that a rocker pedestal had cracked & SPLIT! (that REALLY stunk) When I used the shims made out of flat sheet metal it effectively increased the diameter of the rocker shaft- putting more stress on the "tips" of the U - shaped pedestal until one cracked. I had to grind the sides of the shims to be thinner than the bottom around the bolt hole.

So you should set rocker geometry correctly, set adjuster screws (I believe you want 1-2 threads to be visible under the rocker) & lastly make up custom length pushrods to fit. pushrod kits are much cheaper than head & valve repair.

Side note, OE hydraulic lifters do NOT work well with higher than stock valve lift or spring load. They have an annoying tendency to collapse on whatever valve is mostly open when the engine is off. Since they oil thru the rocker, the lifter wouldn't pump up again because of high clearance on start up. (dohh!)

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63 Valiant Wagon
225 - 4 bbl