Hoo boy! Sounds like fun.
I would tend to prefer the system that feeds 1 from the front main, 4
from the rear main, and 2+3 from the center main. This is the setup on
my Fiat 1100 Formula Junior motor, and it seems to work well. The Fiat
crank is quite simple. All of the drilled holes go right thru the
crank. There are no plugs to fall out, or extra passages. Each journal
has a hole going straight thru. The front and rear main journals have
an intersecting passage straight thru to the nearest big end. The
center main has 2 intersecting passages to the 2+3 big ends. The main
oil gallery in the block is quite large. The oil is pumped out of the
motor to an external filter and cooler, then back into the main gallery
near the center main. The oil pressure gauge port is on the main
gallery. There is a bypass on the pump. An external bypass valve might
offer more adjustability, but would require more plumbing. More
plumbing = more leaks. ;=)
My motor also has a double volume oil pump. This was fabricated by
taking a stock pump body, machining an extension to the body that
matched the cavity, and stuffing 2 sets of factory gears in it end to
end. The shaft was extended and a bushing was put in the bottom plate.
The bottom plate is heavier than stock too. The pump body, extension,
and bottom plate are held together with longer bolts, and roll pins to
ensure proper alignment. This way, you don't have to make special
gears, or another whole pump body, just the lower bits. The pump has so
much excess capacity, that a little extra clearance is not a problem.
The alignment of the new shaft was pretty critical, tho. Watch out you
don't grind down whatever it is that turns the oil pump. I had that
problem.
A larger sump only gives the motor more oil to play with. It also takes
longer to heat up the oil to proper temperature. I was using Valvoline
Racing 20W/50, but switched to Mobil1 15W/50.
The big danger of allowing the motor to overpressure the oil is that it
will leak everywhere, or burst something. Too much oil on top of the
head could drown the valves, and make the motor smoke, or foul a plug.
Oil coolers are sensitive to overpressure. I replaced all the external
oil passage plugs in the block with set screws in threaded holes. The
external oil plumbing is all stainless braided Teflon hose, including
the one for the gauge (I used brake line hose). It runs about 40 psi at
idle hot, 65 psi flat out. While warming up those 7 quarts of oil, I
see 70 psi. I would be leery of 100 psi, but if others have done it,
maybe.
My motor does have a heavy brace bar across the center main. When a
main or rod bearing bore goes "pear shaped" it's because one end is
still round, the sides got stretched, and one end is pointed, just like
a pear. Machinists will call it pear shaped if the difference is a few
thousandths. If you can see it, the parts are scrap metal. ;=(
Lastly, a question: Where is Phoenix located, and do they do cranks for
motors other than the British? I've been wanting a billet crank for the
Fiat 1100 motor, but I haven't been looking that hard. It runs OK with
a factory crank, but I do keep the revs down a bit.
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