Panhead Rocker Arm Bushings

[billpedalino]

For many years, I've been wondering what the purpose of the hole in the top (Bronze) section of the panhead rocker arm bushing was for. I can see no purpose for it. Initially, I thought it was for increased oil flow to the dripper that lubricates the valve-end of the rocker arm, as the holes were always installed on the two intake arms. However, this can't be the case, as there is no physical connection between the drilled hole and the oil flow nor is there a milled galley from the hole to the dripper or any other critical area. I don't think that this hole serves any purpose. But I do wonder why the Factory spent the money to install this hole.

I'm currently matching up random top and bottom sections by surface grinding and honing and can make up three complete sets, but I only have one upper bushing with the hole and don't want to drill these holes in the remaining two intake bushings if it's not necessary.

Any insight would be appreciated.

Thanks.

[kg993]

I don't know this for a fact, but the only reason I see for the hole in the intake side only is to relieve some pressure so the intake oiler will not over oil the valve stem.
I hope someone with more knoledge will confirm or set it straight.
Kerry

[T. Cotten]

The holes were to let oil in, not out.

Contrary to folklore, the felts are not sound dampeners, but reservoirs of oil to lube the top end for start-up.
(Indian Fours used them years before.)
The elevated intakes benefited from additional holes.

....Cotten

[kg993]

Thanks, that makes more sense.