Question about rocker arm side to side clearances.

[Chargerguy74]

Just installed my comp pro magnum roller rockers on my 440 with the provided spacer/hold down kit and these things are tight for side to side clearance. With my 2 outside hold downs pushed to the outsides as I torque them I can achieve only 0.018-0.020" clearance per pair. Comp recommends a minimum of 0.030". I'm going to be taking my hold downs in for machining to gain some clearances but I have the following questions:

Should I, or do I, need to run shims between each rocker and holdown for wear purposes? I was hoping to stick some shims on either side, but just have the 0.018-0.020" clearance total to play with.

If I need to run shims, should I also run shims between each spacer and rocker?

Thanks!

[ws23rt]

I am going to add my   without being up to speed with exactly your situation.

1-- you have found 0.0018-0.0020" clearance per pair and recommended is 0.0030"---  We are talking about it being on the tight side.
I suspect that if you remeasured several times (and you may have) you might find all is well at the tight end of spec.

2-- we are talking about such a small amount it's a tough call to machine stuff when it may not be needed.

3-- let's say you have machining done and are now back to shimming things to get that 0.001" you were looking for?  Would you feel ok with 0.004"? vs 0.003"?

If I were where you are I would go with what you have. It does not make me nervous as I expect breaking in will add clearance in short order.

A stack up of measuring new parts with oil between them is tough at best to be accurate.  

4---when the cylinder head heats up it will get bigger. Longer is one of those dimensions making your rocker side clearances increase. The width of the rockers will expand as well but less by comparison due to their width.  (expansion is linear)  Your hot clearance could well be around 0.005"  

BTW my lawyer told me that I'm ok if your system fails.  I'm just passing on my opinion.

[Chargerguy74]

Lol at the last part there. So what I'm getting is 0.02" max side to side clearance for each rocker pair. Comp recommends 0.03" min. So I'm short 10 thou right there. And this is with zero shims.

I was kind of content with running like this, BUT, would you run your rockers without any shims between them and the hold downs? I'd like to minimize wear on my rockers by throwing some shims in there, but not sure if it's required??? I'm sure if it was, comp would have included washers to go between the rockers and hold downs, or at the very least some shims. Maybe I'm over thinking things here.

[ws23rt]

Lol at the last part there. So what I'm getting is 0.02" max side to side clearance for each rocker pair. Comp recommends 0.03" min. So I'm short 10 thou right there. And this is with zero shims.

I was kind of content with running like this, BUT, would you run your rockers without any shims between them and the hold downs? I'd like to minimize wear on my rockers by throwing some shims in there, but not sure if it's required??? I'm sure if it was, comp would have included washers to go between the rockers and hold downs, or at the very least some shims. Maybe I'm over thinking things here.

When you say you are short "10 thou" are you just adding up the total amounts?  You may be overthinking this.
The rockers float on the shaft and should see little side load in operation.-- Making clearances here close IMO is just prudent to help stabilize the system for it's break in process.

I look it this way---I have never heard of a need to re establish a close rocker side clearance as an important step that needs attention like (for example) valve lash adjustment for solid lifters.

The hemi uses springs (and light ones at that) to hold the rockers in place. A different design of course but the idea of little side forces being involved is my point.

About your question about machining and adding shims.  If you did this you would perhaps be back where you are now but with that add 0.001" per rocker. And now the added shims that you would have would see the little or no wear that the rocker would see had you not done all that work.

[Chargerguy74]

I think I am overthinking it and you're right, the shims/rockers would probably see little to no side wear. I'm going to go without adding shims. I think I will still either machine down the spacers or hold downs to gain another 0.010"-0.015" side to side clearance for each rocker par, to total the 0.030" clearance per pair Comp recommends.

[Kern Dog]

I bought a 1.6 aluminum rocker set from Mancini Racing a few years back. The holddowns were a bit thick, causing a bind in the rocker movement. I simply filed them down a little, trial fitted, etc until it all fit well.