Triumph Repair: oil pressure, oil pressure gauge, hydraulic gauge

Question
Hi. I have a 1980 Spitfire whose previous owner restored her with some modifications. Those being twin S.U.'s @1 1/4, mild cam, ported and polished, dual spring valves, stainless valves, oversized intake @1.44, oil cooler, headers, stainless exhaust, auxiliary. electric cooling fan (180 degrees) and a Ford 2.3 Turbo Electric Distributor. The car runs exceptionally well, and other than a slight lope at idle, you would never know it had been modified until you get under way. However, I've noticed that stone cold my oil pressure is 50lbs @ 1000. But, after it gets warm, say after 1hr. of driving it drops to slightly above 20lbs @ idle. Is this indicative of a problem that needs to be addressed now ?

Thanks,

Jack

Answer
Hi Jack,
It is low but may or may not be serious. If this car was brought in to me in a dealership I would first connect a known good hydraulic oil pressure gauge to the block and confirm the readings with warm oil.

I like to see 25 to 35 PSI at 800 to 1000 RPM and from 50 to 70 at over 1500 RPM. If it is confirmed low I would closely examine the oil and ask what grade of oil was used. (10w30 in cold and 20w40 in summer) also ask when the oil was changed and note on the dipstick if the oil seems thin. (even the correct oil after run too long will get contaminated with fuel making the oil too thin and low oil pressure.) This is more so with a hopped up engine as combustion chamber pressure is higher and thus more blow by. If a oil change is due I would suggest a oil and filter change before deciding there is a problem. (fresh oil can be saved if it is necessary to open the engine up)
If all this is correct and you still show low pressure on a hydraulic gauge connected directly to the block then remove the pressure regulator valve and check the spring and the valve.
If that is to specs then I would remove the pan and pull several rod caps and use "Plasti-Gauge" to check oil clearance. I like to see .0015" to .002". (.0025" is an outer limit but then I would consider using a 20w40 or 20w50 oil.) Some race engines use higher clearance but they also use high volume oil pumps and run at high RPM most of the time.
If you find the Rods at .0015 to .002 then I would pull down the main that can be pulled without removing the engine and "Plasti-Gauge" it. I like to see .002" to .0025" on the mains but have seen .003" work ok.
Any scars noted on the crank that you can feel with a finger nail should warrant pulling the engine and redoing the crank and bearings.
Howard