[Grady Clay]

Doug,

“The plugs in the case and crank were removed and replaced. My builder suggested if any came out, there would be ZERO pressure at all rpms.”

I don’t think so. The crank is fed from #1 and #8 main bearings. The oil system pressure is measured in the main oil galley in the case. If a plug came out of the crankshaft, particularly in the middle, it would only affect the main oil pressure at idle. Once the engine is at revs, the extra loss of oil is compensated for by the pressure regulating relief valve not opening as much.

The dangerous part is the nearby rod bearings aren’t seeing as much pressure as they should or consequently passing as much oil. There is some oil but not the normal quantity or pressure (the bearings themselves operate at very low pressure, the edges being zero, but flow quite a bit of oil.)

If this is the situation a bearing haven’t failed – yet.

I understand that if a piston squirter falls out, the symptoms are the same. I just got off the phone with a friend who had that happen about six weeks ago. No indication of a problem on track. When he came off track (200F Mobil 1) the standard Porsche oil light flickered and came on full at about 1000 rpm. He revved it up and the light was full off by 2000-2500 rpm. Not his normal situation so he shut it off.

Upon disassembly a piston squirter was in the bottom of the engine. I saw the rod bearings. There was some discoloration on the crank from too hot oil film (probably from the low pressure and flow) but no damage. He had the crank polished and inspected, and replaced all the bearings. Needless to say the piston squirters are firmly in place.

This clearly indicates to me that even a missing oil squirter doesn’t divert enough oil to have the pressure be zero and will even turn off the oil light at modest revs.



While I’m not a fan of the restrictor fittings in the cam oil circuit, would this engine have come with them? If so, did they get changed out and replaced with the full-flow earlier version?

I have both center oiling and spray bar oiling for the cams in my race engines.

Best,
Grady