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Tech Question
Frank Capobianco, New Hyde Park, NY, '74 Plymouth Cuda 410 sb
Rick, I'm building a stroked 340, long valve W2, roller rocker, roller lifter engine. The right side lifter galley has been sleeved, it will see limited street use. The aluminum blocks that relocate the rocker shaft all have a 3/8" clearance hole top & bottom to mount the shaft. Do you think this is enough space for proper oiling or should I modify the lower hole on the oil fed pier? Also, is the pushrod length on shaft mounted adj. rockers only to prevent pushrod cup to rocker interference if the pushrods were too long & have nothing to do with proper valve tip contact as it would on a ball stud arrangment? Thanks.
Frank-
Ideally, you will run the oil pump with a drill and slowly rotate the engine by hand and actually SEE the valve gear oiling! The holes in the stands are clearance holes for 3/8" bolts - probably enought extra space for the oil. But, offhand, I'd say a rat-tail filing a small groove or notch in the stand couldn't hurt. If it were mine, I'd do it.
The pushrod length does not change the valve tip contact pattern. Too long, as you noted, can cause obvious interference. Having 'em too short has two effects:
1. It actually changes the rocker arm ratio - especially with the valve on, or near, the seat. (all rockers are really variable ratio, this makes the ratio vary more during a full sweep). This has almost the same effect as fast-ramp cams - not a bad thing. But it can slam the valves closed pretty violently, better have good 1-pc. valves. (With a roller cam, I assume you're there already.)
2. However, too-short pushrods causes lots more stress on the adjuster screw.
Therefore, I concur with the conventional view: have no more than 2 or 3 screw threads visible below the rocker arm.
Rick
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