Randall Young wrote:
My experience was that it greatly increased oil burning, I threw it
back in
the parts bin after it cost me a broken piston. .
Unlike the rod and main bearings, the rocker shaft does not require a
constant flow of oil for cooling. As long as the wear surfaces remain
oily,
more oil will not reduce wear appreciably. Thus, IMO, the factory
system is
adequate as long as you keep the oil changed often enough to prevent
sludge
formation.
If you just let the engine idle, you'll only get a few drops flung
around.
Anything above idle, and you can expect everything to get a pattern of
oil
dots. It's not the flow itself that's the problem, but as the oil
runs down
the rocker, the motion near the tip is violent enough to fling off
droplets.
I agree entirely with Randall's view on the need (?) for an additional
feed. I bought one - more out of curiousity than anything else. Fitted
it one day and threw it out the next. I suppose they might be a good
idea if the car is used for racing but I can see little point in
fitting them for normal or fast road use. The secret here is to ensure
the internal, rocker pedestal and shaft drillings are clear of sludge
or swarf obstructions. This would probably be a foregone conclusion if
the engine has been rebuilt and thoroughly washed in the process
before reassembly. Even if the engine hasn't been stripped down, you
can do a lot with a piece of welding wire to ensure feed holes don't
get choked. The use of a high quality oil (mineral or synthetic with
its usual detergents) allied to regular oil and filter changes will
ensure those drillings stay clear. A continuous 'ooze' of oil the full
length of the rocker shaft with the engine at idle and oil droplets
being thrown all over the place, are the assurances the rockers are
getting sufficient oil.
I have seen plenty of newly supplied and fitted rocker shafts with
high levels of wear in less than a year. Mostly, these are proof of
shafts with insufficient hardness. ISTR the original factory spec was
in the region of 65 Rockwell - anything substantially less than this
will soon wear out and mistakenly suggest to the owner that an
external feed is the only course. I changed the shaft on the PI last
week for a NOS item. This was because the shaft I'd bought from a
leading supplier wore out in less than a year and had about as much
hardness as a piece of putty. There was still plenty of oil
circulating round the rockers and an external feed wouldn't have
stopped the wear that had taken place.
Jonmac
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