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I have heard of guys having the rocker stand blocks machined on the bottoms .040 or .060" in certain instances so the geometry looks better.  Are the rockers close to perpendicular to the valves at half lift?  Are you doing this with a light checking spring so you can see the contact pattern through the cycle?

Al, did you look at the pictures? It appears, correct me if I'm wrong, that Sharpie was applied to the lash cap. You can see the contact pattern.

Machining the rocker blocks sounds like a good option. I had forgot about doing that. I'll be doing rocker geometry soon myself when I get the customer motor built to that point.

I worked on rocker arm geometry today on the 2276 I'm building. I'm waiting on a Total Seal #2 compression ring set and machined cylinder spacers, otherwise the long block would be built. I have a set of .090" spacers, but need .180" so they got stacked temporarily on one side to do the geometry.

This picture illustrates what JB is talking about perfectly. The exhaust valve on the left was no shims installed, and the intake valve on the right is with two shims of .060" so .120" just to illustrate the point. More shims moves the contact area away from the rocker stand, which makes sense since the valves are tilted slightly toward the rocker stand.

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I'll be taking the rocker blocks to a shop to take .030" off the bottom.

The Sharpie trick is AWESOME! Thanks!

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Last edited by DannyP

I got after the geometry today. Webcam 86b and Berg 1.45:1 forged lifters. Lift is 0.551" at the valve. CB CNC 044 Super-Pro 45x37.5 heads and port-matched manifolds. CR 9.8:1, 82 stroke x 94 bore. Chambers are flycut to 58cc, 2276cc should be a screamer on Weber 44 IDF in a Spyder.

Just need to cut the pushrods, my adjustable pushrod is set to the correct length.

The contact pattern on the lash cap is perfect even though the picture doesn't show well. I used dry erase marker this time.

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Full lift:

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Zero lift:

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Two threads above the locknut and two threads underneath. Rocker is tangent to pushrod and valve at half-travel. I forgot to take the half-lift pic.

Also the cam card verified with degree wheel and dial indicator.

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Images (3)
  • 20210508_143927
  • 20210508_140058
  • 20210508_135957
Last edited by DannyP

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