Well I drove the 66 again today. I am amazed at how high the oil pressure is. According to my new mechanical gauge I installed in the cab I am getting 80 psi at cold startup, when the engine is hot and idleing at around 750 RPM im getting 45psi of oil pressure. Going down the road in high gear im getting 60-70 psi of oil pressure. I dont understand why the oil pressure is so high, my bearing clearnces were a bit on the tight side, but still this is outrageous. This is with Mystik 10w-30 dino oil and a motorcraft oil filter. Can an engine have too much oil pressure? Also am running a Melling High Volume oil pump with stock pickup tube.


Thanks


FERacing66

 

FE, sure too high of pressure is possble, but you're not there, or even close. My 352 used to go over 120 on cold winter starts ( 70 wt oil ). I was nervous but nothing ever went wrong. I was running the thick oil as a crutch, when the engine was warm, in the summer, it idled at only 10lbs. Lots of folks would love to have the oil pressure your engine has. If you are worried about it, switch to 1030 synthetic, I'll bet it will go down some. But I wouldn't be concerned. DF

 

this is a pretty new motor, right?

I certainly would not consider it a problem at those pressures. It might drop as things get broken in more. Sounds like you got a nice tight rebuild. How is the running temperature?

 

i have the same oil specs you do i get about 80 psi cold startup and 40 psi at hot idle at 1000 rpm and 38 psi in gear at idle and about 65 psi at 3k

 

Yep I just rebuilt it. The operating temp is good it usually stays around 180 but will creep up to 190 if it idles for long periods of time or if I am running at WOT. This engine has always had extereme oil pressure, before I rebuilt it it had almost no oil pressure, now it has outrageously high oil pressure. Scouder, rusty and gtex, what oil pressure do you have? Who can complain about high oil pressure? =)

 

When hot, mine idles in the teens, runs at speed from 40-80psi depending on engine rpm..

 

One more question, what are your main bearing clearences?

 

Well, I run the 15w40 Mystik, and I get 75psi on a cold start, 50psi going down the road w/ hot engine, and 15psi hot idle. Idle speed has a lot to do with it too, I idle it around 750rpm hot. I should note that there are used rocker arms in it, which contributes to the low pressure at idle. I am running a Melling HV oil pump.

As far as the motor is concerned the pressure cannot be too high. The more oil going across the main and rod bearings the better. There will come a point that you explode the oil filter though, but like DF said, you're not even close to that.

Oh, and my bearing clearances were on the looser side, like .0015" - .002".

 

Yeah I think its a fluke or something ive never seen oil pressure like this. My rockers are used too, they were full of gunk and sluge though so I took em off and disassembled them and cleaned the shafts out and cleaned them so oil could get though, the shafts had so much buildup of sluge/gunk that oil was not passing through them.

 

I used to run a 100 lb relief spring...and that would give me near 150 psi COLD!!! WOW!! Never hurt anything, never leaked a drop more. I since have removed that spring and run a shimmed stock spring and get near 100 COLD, maybe 30-40 hot idle. Most times, I run .0025-.003 clearance down below, but to be able to turn it higher you need a bit more room for oil.

Yours sounds like a good solid pressure for a nice motor.

 

That sounds fine to me. I have .002" on main bearings 1,2,4, and 5, 3 has .0025". Rods are all at .002". 70 lbs at cold start, 50 lbs warm at 700 RPM idle. I would be happy with those pressures!!

 

I love lots of oil pressure in my FEs. My last was a 66 427 Side Oiler and it ran 85 at startup and 50 or so at idle with 20/50 synthetic in it. If you are concerned run a lighter weight oil.

 

That’s a good looking engine. What’s it in?

 

I don't think your oil pressures are outrageous at all for a new engine on the tight side. Some of the REALLY high pressures mentioned by others can cause some pretty inconvenient trouble-twisted off oil pump driveshafts are no fun. Neither are exploded oil filters. Both result in no oil pressure with perfectly good ignition. The bearings then self-clearance in short order.