BG info: I am checking the wipe pattern of the Yella Terra YT6670 roller rockers adfter having my heads "fixed" and milled .030". Using GM OEM head gasket, heads torqued to spec using ARP head stud kit. YT rockers come with shims to put under the rocker to raise the pivot point as needed. They only supply one shim per rocker, but after reading on here and other places over the past week or so, and watching the Straub video on proper rocker arm geometry, I decided to check additional heights as well.

Got my heads back on and measured everything last night. Can y'all please check my logic and math here? I did a sanity check and checked all cylinders with no spacers, and all were within 0.005" of the same length pushrod needed to get zero lash. So I felt comfortable that the rest of my testing could be done on one cylinder and apply to all 8.

I then measured the wipe pattern width of the roller on the valve and lash cap of the assembly with no spacer. Wipe pattern was centered, but a little wide. I then added 1, 2, 3, and 4 spacers and re-adjusted PR length to zero lash and measured the wipe pattern width. So based on the data I collected, I looks like my best setup would be buying 0.063 shims for the rockers, and 8.750" pushrods. Does that look right to y'all based on my numbers below?

No spacers
Pushrod length with zero lash - 7.655" overall length - gauge length = 7.640"
Wipe pattern width is centered and 0.115" wide

One spacer - 0.021"
Pushrod length with zero lash - 7.690" overall length - gauge length = 7.675"
Wipe pattern width is centered and 0.109" wide

Two spacers - 0.042"
Pushrod length with zero lash - 7.725" overall length - gauge length = 7.710"
Wipe pattern width is centered and 0.100" wide

Three spacers - 0.063"
Pushrod length with zero lash - 7.755" overall length - gauge length = 7.740"
Wipe pattern width is centered and 0.082" wide

Four spacers - 0.084"
Pushrod length with zero lash - 7.790" overall length - gauge length = 7.775"
Wipe pattern width is centered and 0.100" wide

Pic of wipe with 2 spacers


Pic of wipe with 3 spacers


BTW, Straub's video is here. If you have not seen it, watch it. It has a lot of good information.

 

Anyone? Bueller...