OEM 340 6-pak engines did have the machined pad and jam/lock-nut on the adjuster.
Got a few questions:
* Does the OP have hydraulic lifters? (273 pushrods are normally about .25"-.30" too long for hydraulic lifters.)
* Were the rockers shimmed because the pushrods were too long?
* Mis-adjustment and/or rocker-to-retainer interference could have contributed to the bent pushrod as well.
FWIW, I don't have any to compare side-by-side, but I believe some
aluminum rocker manufacturers, like Harland Sharp, use the bigger adjusters.
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