Part 4- Pushrod clearance. Mock-ups

During today’s mock-up, most of the intake holes needed another 0.010” near the top (compared to pre-machine work Part 2 clearancing). Since the final/actual lifter location on the base circle, and the final pushrod length, required turning the rocker adjusters about 1.5 turns from the factory supplied position (which was screwed all the way in, i.e. minimum cup sticking out.) So, at max lift, the pushrod end of the adjuster was a little farther from the valve than during Part 2 when I couldn’t put a lifter in the unfinished bushed lifter bores. My final clearance work changes the Part 2 distance “0.125 inch” to “0.145 inch”.

From Part 2:
The T&D 1.7 ratio rocker part number 8013, 5/8” shaft, paired rockers per cylinder will require elongating the pushrod holes in the heads toward the intake manifold side. The T&D catalog shows the #8013 set uses 0.080” longer rocker arms than the typical B1 single shaft per head setup. So that explains the holes needing to move toward the intake manifold, away from the valve side of the heads. And my first mock-up shows the holes do need that work, especially the intake pushrod holes. I used a 5/8” dia endmill and moved the centerline 0.125” toward the intake manifold side. The heads originally had a 5/8” dia hole for the intake pushrod, and a 3/4” dia hole for the exhaust pushrod. So moving the centerline of the larger exhaust hole with the 5/8” endmill had less affect than the intake holes. Pictures are in my post in Part 2.
Note, the 0.125” move is more important at the top, rocker end, since the pushrod will angle back to the same lifter location.