>might not be a good idea to enlarge the oil feed holes
The whole upper end lube problem is a myth. An engine in "good"
shape places plenty of oil up there. You can see it dripping out of
the rockers on a running engine. They raced these engines, remember?
To my knowledge the rockers were NOT a problem when these cars
were new, only after 50,000-100,000 miles.
The problem is in people's understanding of the problem AND in
the word "good". Many shafts are partially clogged, I doubt
there is any way to fix this short of removing the end plugs
(you did install these in the new shaft?) and running a bore brush
through it, then clening each hole.
The oil pump itself could be "tired" and no longer keeping the pressure.
It is possible for the hole down to the oil pump through the block
to be clogged or for the head gasket to not be installed correctly
and clog the passageway.
THE MOST LIKELY PROBLEM though, is loose bottom end bearings. These
wear rapidly, especially the middle main ones till the 1 to 2 thousand's
clearance exceeds 5-10 thousand's...
(use plasticgauge to check the ones in the middle and after the change
to make darn certain the crank is stock, else you'll need 10 or 20
under rod and/or main bearings, get a couple of sizes of thrust too)
(oil gauge reading can be a question as well, verify)
Don't know about you, but if I was 30 wt. motor oil under 60 psi pressure
and had a choice of traveling 12" to the main bearings or 36" to that
front rocker via a bunch of small passageway's, I'd rush right to that
main bearing and drown the cylinder walls with excess oil spray. This
oil can be easily grabbed by the rings for a quick burn.
On most original old engines its just place stupid to replace the
rocker gear WITHOUT replacing all the main, rod, and thrust washers.
One of my cars rated less than 10 psi on my "interstate" oil pressure test.
(i.e. 10 miles of interstate followed by a 1,000 rpm idle at exit ramp)
New rod, main, and trust washers installed from under the car (no new
oil pump, though I would recommend this if the engine has 100k+ miles
on it) changed the oil pressure per above to 45 psi.
1. hot idle oil pressure using the "interstate" test is 45 psi
2. dropped the oil comsumption from a quart every 100 miles to each 500.
3. allowed a nice flow of oil to the front rockers
4. the new rocker gear now has 50,000 miles on it with no wear
5. the valves stay adjusted and NO gray grinding on the rockers
For $100, this was the best change I ever made...
(really careful to follow the torque's as you can EASILY ruin an engine)
(ask for help from someone that has done this before, just ask someone
that owns more than one TR6...)
--
Roger G. Bolick, rgb@exact.com 512-794-9567, FAX 345-2879
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