Hi all,
Years ago when I was burning up the streets in my 73 240Z ( between my
TR6's, I'm sorry I had a weak moment ) , I used to do time trials at
Bridgehamton race track. Before heading up to the track I changed the
oil using Castrol 10-40. After doing some laps I glanced at my oil
pressure gauge & freaked. The Z oil pressure was always excellent, but
now showed almost 10lbs less at idle & 15lbs less at speed. Still not in
any danger zone but a significant change. This does not necessarily a
bad thing as high oil pressure is a waste of power & serves no purpose.
In comparison the Z motor is far superior in lubrication than the TR
motor & even at lower readings was still better than a fresh TR engine &
far more thorough in keeping things lubed & cool. After changing back to
Valvoline things went back to previous readings.
Oil pressure has been an issue on the list as long as I have subscribed
& the end result has always been either the motor is worn & needs to be
rebuilt or your expecting the reading to be higher than it should be. A
fully warmed motor in spec using 10w-40 should read about 15-20lbs @
idle & 50-65 lbs at speed (3,000 rpm). Anything more is a waste. I don't
mean a ten minute drive to the store, but rather a 30 minute drive
around town or on the highway. This gives the oil time to warm
completely as well as the entire engine. Even a tired engine may show
75lbs at start up. You really only need 5-8lbs @ idle & 40lbs at speed
for minimum engine safety limits. A thicker oil is only masking the
reason for the loss in pressure. Many of these motors are loosing
pressure in the cam bores after 25 years & 75,000 miles. Most shops will
not install cam bearings as part of a rebuild & these bores wear. These
engines were never known for good oil distribution & that won't change
but if you look around take a count of how many TR's are on the road
with high mileage motors. Low oil pressure or not , these things last a
long time !!!
--
Mitch Seff
Oceanside, N.Y.
75 TR6
http://www.angelfire.com/ny4/triumph5/
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