What is this hole

[Nick9900]

Curious the purpose of this hole on the right side case by the front cylinder between the lifter block

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[SP33DY]

That's where the factory cross drilled the case to connect the front tappet block to the oil feed passage from the rear tappet block. It should be plugged near the top of the hole so it doesn't leak. The factory used a soft plug there.

[kd]

That's where the factory cross drilled the case to connect the front tappet block to the oil feed passage from the rear tappet block. It should be plugged near the top of the hole so it doesn't leak. The factory used a soft plug there.

It may have been removed for the case weld repair in the cylinder deck, fallen out because of it or relocated deeper and out of view in the pic.

[SP33DY]

I have tapped them for a small allen set screw, and it worked out fine. A #3 drill, 1/4-28 tap, and a short 1/4-28 set screw with 243 blue loctite will get it done. Provided they didn't mess the hole up too much getting the old plug out.