[DeTomaso] High Volume Oil Pump?

[JDeRyke at aol.com]

Tom, most guys find that a stock pump works just fine unless you are running 
a remote oil filter AND a remote oil cooler; then, due to flow restrictions 
from long oil lines, sometimes a high volume unit is needed to maintain 
pressure.  FWIW, I run both and still use a stock pump. True pressure at start-up 
(cold engine) will be 75-90 psi, hot pressure @2500 should exceed 50 psi, idle 
should be 20-30 psi. More than 90 psi can cause problems with oil filters and oil 
coolers as they will sometimes rupture w/cold oil, so I recommend NOT using a 
heavy spring in the oil pump relief valve- which is often the only difference 
between a stock and a 'high-pressure' pump. I once blew a Wix filter clear 
off the block at 6500 rpms w/a 'high pressure' pump, heavy spring & 50-wt race 
oil....
You should verify the pressure readout- as with the stock water temp gauge, a 
stock oil pressure gauge lies constantly. Add a tee fitting to the block 
outlet, screw the stock sender into the side port and a cheap mechanical gauge 
from Pep Boyz to the top. By comparing both gauges, this will give you a check of 
the notoriously inaccurate stock electric gauge. FWIW, I once talked one 
vendor into letting me 'borrow' a handful of senders for our '72: of nine (9) 
brand new senders, ALL gave different values on the same engine and all were lower 
than my $15 mechanical gauge! I picked the highest-reading of the bunch but 
left the mechanical gauge on the engine.... since 1990, with zero problems. 
IMHO, a stock gauge is best regarded as an 'idiot-light' to tell you the pump is 
turning but no other accurate info can be gotten.
Second good idea: add an aftermarket pump driveshaft to the oil pump you 
choose. Stockers are apparently made of old coat-hangers and will twist, then 
break. A Moroso, Milodon or SVO unit of 4130-steel sells for $17 and will not 
break or twist. Finally, an integral part of the oil pump drive is a double 
thickness roll pin (or a piece of drill rod) in the distributor drive gear. Good 
luck- J DeRyke<BR><BR><BR>**************************************<BR> See what's 
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