Mitch---The design of the TR6 engine did not call for "extra" oiling at
the rockers. It can be a subject for long debates, as the reasons for
adding an external oil line to supplement the one built in to the system
are varied. To be sure, there are trade-offs. Poor quality, non-hardened
rocker shafts that wear out quickly seem to promote the idea that more
oil is required. Or competition valve springs!
Overhead cam (Z) engines obviously need more oil at the rocker area.
If you were to rev a TR6 engine with the rocker cover off, you would see
that the oil increases with the rpms. At idle, it simply isn't
necessary. (Take the oil cap off the cover and rev the engine, to save
yourself a cleanup!) Personally, I prefer to have my oil flow and
pressure going to the rod and crank bearings. Any spur line takes a
little away from this.
When the valve guides are in good shape, the extra oil afforded by an
external line will eventually drain back into the sump. No harm, no
foul, as they say. When the guides start to open up with mileage, it's
convenient for oil to get sucked into the combustion chambers, rather
that let gravity do its job.
Dick T.
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