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426 Hemi Rocker Tip Geometry Adjustment

ignition1

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I haven’t been able to find much information on how folks adjust the rocker arm tip to valve stem geometry on a 426 Hemi.

I have a fairly stock 426 Hemi setup (factory block, factory heads & rocker assembly, stock valves with touched up seats)

My deduction so far is either cut the rocker stands or add shims? In my case add shims, but where to get shims?

Except for dropping for a Ray Barton or Jesel setup, wondering what is normal practice?
 
Blocked decked .010 and the heads maybe .005 to clean them up.
 
Cutting the heads/block would not change rocker to valve geometry.

I'm running stock ductile rockers and stands (later MP stuff) and didn't see that I could improve geometry much other than replacing the rocker system entirely.
 
Cutting the heads/block would not change rocker to valve geometry.

I'm running stock ductile rockers and stands (later MP stuff) and didn't see that I could improve geometry much other than replacing the rocker system entirely.

Agree. It might require a different push rod length, but the valves/springs and rocker stands in relation to eachother wouldn't move with cutting material off deck height or head surface. They do make offset shims for the standard big block heads and I would imagine they would make similar for the Hemi, but not a hemi guy so someone should chime in.
 
I know Harland Sharp and others actually make different offsets in their rockers for different head brands. I coulda swore I saw some shim kits that would offset the shaft closer or further away from the valve for such instances using different valve train components with different combinations.

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Theres also crescent shaped shims in this set as well in this article. You can kind of see them in the front of the rocker shaft between it and the head mating surface where it lays into the half moon area.

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You would have to space all the stands up.
https://tdmach.com/product/shim-426-hemi-intake-060/ace

I've never spaced up the stands, I do however use collars and shims to center them over the valve tips.
These are the collars and at the bottom of the page are the shims which I am sure you can source from all kinds of vendors, they're just shims that would be used in a variety of applications for that shaft size.

Hemi Alum. Rocker Arm Collar Set
 
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this is #7 in the closed position, contact at like 5-10% on valve stem.

The valves stem heights were set with the seat re-grind, so the valves could be sitting slightly higher Which is leading to the issue.

according to the article I can see how a longer push rod can affect valve timing at low vs high lift, but I don’t see how the initial contact patch would change with longer/shorter pushrods.

Wouldn’t the adjuster accommodate the pushrod length difference and the fulcrum position still does not change relative to valve tip.
 
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this is #5 exhaust, the rocker arm looks short overall and doesn’t really cover up the valve tip. contact start at 30% and ends around 90%.

I know about the lateral shims that go around the rocker shafts as #5 has some of those shims installed.
 
You have a few choices now that we see what every hemi owner deals with none are easy.

1. Use lash caps which is the easiest but not perfect.

2. Have machinist thats weld up exhaust tips. Regains.

3. Longer valves.

4. Weld up seats and re machine expensive.

5. New rocker assembly and valves 7500 not worth for stock motor stage V and shafts
 
Mmm… :/ Haha Hemi is special... and expensive.

From the looks it I wouldn’t expect nice contact patterns if I were to actually run pattern, I could swap around the rockers to see if there is a better fit, but prob. not life changing differences.

The rockers are making contact on the tips, wider sweep than I would like, but for a street car would there be any BIG reservations to running the setup as is? Cruise night, traffic, maybe 6k on the occasion.

I know it will not get most performance out of the setup and will have to do a valve job sooner.
 
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