There have been a number of reports about a mis-drilled rocker arm shaft oiling cross-hole drilled in the #4 camshaft journal. If this hole is not drilled in the correct location, the oil flow to the rocker arm shaft and the rocker arms will be substantially reduced or non-exsistant.

The best way to check a cam for the correct oil cross-hole placement is to use a cam bearing for the #4 location. Slide the bearing onto the rear cam journal and see if the holes in the bearing line-up to the cross hole in the cam. The holes will only line-up in one position.



One other way to checK is to mark the cam and engine block surfaces and check to see if the marks align during cam rotation.



If the hole does not allow oil to flow thru the cross-hole and bearing holes, the cam or bearing should be reworked. The cam journal can be grooved or the cross-hole's entrance elongated in order to get proper alignment. The bearing can also be grooved in a way that allows a flow path for the oil, even if there is no cross-hole in the cam.



Here is a drawing showing how the cross-hole is drilled.


One "work-around" fix to a rocker arm shaft that does not get oil is to drill and tap a separate oil feed hole into the lower rear cylinder head bolt hole. Use a piece of tubing to feed oil into that location and it will oil the rocker arm shaft.
DD

Doug, could you also grind a small groove around the rear journal like a hydraulic cam?

_________________
Official Cookie and Mater Tormentor.

Slantzilla

This is kinda what they do with the Big Block engines (sometimes), that way the rockers oil with a constant flow instead of a pulsed flow. But I would want to be real carfull and follow up with very good oil pressure checks in all conditions & the oil flow up top also. That external tap in looks like something worth looking into itself, the oil could be controled with jets to insure that the top wasnt over loaded & taking away from the bottom. There is usually a fair bit of HP gained by controlling the oil good in a engine.


Jess

That's what I have been doing on all my cams. I do it freehand, with a die grinder with a cutoff wheel. Looks like s**t but works. On a side note, if you wind up with too much oil up top, it is easy to remove the valve train and tap the hole in the rocker stand. Then install a allen set screw, with a metering hole.

_________________
Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225