Rocker Arm Shims

[SpeedL#]

I have a 2000 TJ. KB pistons and a comp cam 163-000-5. The block was deck .020, do I need to place shims under the rocker arms?

cam specs
grind 5206/5205 H 113.0
Duration @ .050 206/212
Lift w/ 1.6 ration .435/.448
Advance +3

Thanks

[IH 392]

Shims on the rocker pedestals are to correct for valve stem protrusion to correct the geometry, nothing you told us has any value on the rockers needing shimmed?

[SpeedL#]

Thanks, guess the question was if the shims affected my push rod length. Sounds like stock rods will be fine?

[SilverXJ]

The shims will effect preloaded. However, adjusting the preload is not their intended use. They are intended to adjust the rocker arm to valve tip contact geometry.

While you might not need replacement pushrods with .020" taken off the deck you don't mention any other changes. Valve job, head milling, different rockers, ect. can all effect preload.

I would purchase a Comp Cams checking pushrod and check for correct length. The part number is in the FAQ section. At the bare minimum I would check preload with a stock pushrod and go from there.

[Retlaw01XJ]

The shims will effect preload. However, adjusting the preload is not their intended use.

True, but in a pinch, you can use shims to get the lifter preload in range.
I cut my 2001 block 0.020", took a few thou off the head to get it flat, and with a Victor head gasket mild Crower cam, and stock rockers, ended up with too much lifter preload.... shimming the rockers about 0.065" got the preload right.
Shims can throw off the rocker geometry, especially with higher-lift cams.
As stated, put it together and measure lifter preload, and go from there.

[SpeedL#]

I did not anything shaved off the head. Stock push rods and rocker arms is what I have. I will put it back together and check it.

[Retlaw01XJ]

Sounds like a plan.
I don't know why mine changed so much. I did swap to a later 2004 'TUPY' head, maybe that was it.
There are other variables such as camshaft base circle diameter, and valve stem height...a valve job will sink the valves a little, and valve stem tips may or may not have been reground.
Every engine will be a little different, so lifter preload should be checked.

[SilverXJ]

Sounds like a plan.
I don't know why mine changed so much. I did swap to a later 2004 'TUPY' head, maybe that was it.

You decked the block .020", took some off the head (.005 or so?), and did you use the MLS head gasket? (.010" less or so than stock) = .035" extra preload.

There are other variables such as camshaft base circle diameter,

good point. I forgot that.

[SpeedL#]

We'll turns out my 0331 head was cracked. I got a new cylinder head. From Clearwater in FL. Now I need to get spring that can handle the lift. It seems the mopar performance springs are on back order. Anyone have recommendation for another spring that will work? If I do find some mopar springs will my stock retainers and locks work? The part number for the lock is a single groove lock. My current valves are three groove.

My cam is lift .462/.478