351C Low Oil Pressure at IDLE

Jim Barnett · #1 (**permalink**) 05-17-2005, 06:02 AM

OK, you Cleveland experts, here's another question I'd really appreciate your responses to: my Cleveland seems to run fine, BUT I'm VERY CONCERNED about the oil pressure readings I'm getting. On inital startup, my OP reads around 80PSI and drops to around 40PSI at IDLE. After I've driven the car several miles and the car has warmed and/or heated up, the high RPM OP stays between 40-50PSI, BUT the idle OP hovers between 10-15PSI and THAT worries me. Is OP that LOW at idle normal and OK for the Cleveland? It shoots right back up to 40-50PSI as soon as the revs come up. Whatcha' guys think?? The Cleveland in my cobra was reportedly taken out of a "totaled" Pantera and completely rebuilt prior to installing in my car. I don't know all the particulars of the engine, but it does seem "cammy". THANKS!!!

blykins · #2 (**permalink**) 05-17-2005, 06:58 AM

Well they say that you only need 10psi of oil pressure per 1000 rpm's your turning. So if you're idling at 900 or 1000, you would need 9-10 psi. Do you have enough at wide open throttle?

blykins · #3 (**permalink**) 05-17-2005, 06:58 AM

Well they say that you only need 10psi of oil pressure per 1000 rpm's your turning. So if you're idling at 900 or 1000, you would need 9-10 psi. Do you have enough at wide open throttle?

trularin · #4 (**permalink**) 05-17-2005, 07:11 AM

This is how Brent gets his post count up.

Okay, I have a Cleveland and it will limp at 10 to 15 PSI at around 800 to 900 RPM, I just set the idle up to 1100 and the engine likes that much better and I get 20 to 22 PSI.

My set-up is:

Boss crank and rods
Forged 10 to 1 pistons
Mellings HVHP pump
Billet pump drive
Stock Boss heads
ARP studs
Locked hydraulic lifters
8 qt Canton pan with five baffles.
Canton oil pickup
Bosch oil filter
Crane roller rockers
And the engine is balanced and blue-printed.

My max PSI is 85 with Mobil 1, 15W - 50 plus one can of EOS.

My final timing is around 34 and my initial is around 18 to 22. ( it's an age thing

)

Hope this helps.

Jim Barnett · #5 (**permalink**) 05-17-2005, 08:12 AM

THANKS a MILLION guys!!! My 351C idles right around 8-900RPM so it looks like 10-15PSI OP is OK. I may set the idle up a little as trularin suggested. MANY THANKS. I was worried. That 10PSI per 1000 rpm seems to hold true for my motor!!

mannyjoe · #6 (**permalink**) 05-17-2005, 12:49 PM

I don't know if this translates to the 351C but my 302 windsor had the exact same sympton. I switched to a Wix Oil filter and picked up the extra 8 psi of oil pressure at idle that I wanted without having to change the idle speed. You can get Wix filters at Napa otherwise they seem hards to find. HTH.
mannyjoe

CobraEd · #7 (**permalink**) 05-17-2005, 12:58 PM

I don't know about WIX, but Fram is notoriously bad. There have been many articles about how they kill oil pressure. The articles say that Purolator and Motocraft/Ford (which is made by purolator) are the best overall. I switched to Purolator as did a friend based upon my recommendation, and we both noticed a difference.

Ed

sharpe 1 · #8 (**permalink**) 05-17-2005, 04:18 PM

Ford engines all show low oil pressure at idle

Cracker · #9 (**permalink**) 05-17-2005, 05:50 PM

If it continues to decline over time a likely cause could be a bad bearing bleeding pressure.

Fred Douglass · #10 (**permalink**) 05-17-2005, 05:59 PM

...if I set the idle below 750 rpm's (pretty low?) it goes down to 10 psi but "hunts" around a bit. Comes up big-time with rpm. I DO find numbers like 60-80 psi a little "exciting"---wonder what a standard oil-filter blows up at (psi-wise)? As to being "cammy". I'm doing a rebuild (now the target is 408ci, including "Australian" modified 2V heads--supposedly it will
produce 500+ ft/lbs. at c. 4500----or about 1000 rpm "earlier". We'll see. I have researched enough to believe that the Cleveland four-bolt beast is a perfectly good mill for the Cobra. We non-conformists must stick together!

Once the new build goes back together, I will add a Moroso accumulater. Dunno what that will lead to, but I got a little leery of OP looses in tight corners!

G'luck.

racer24 · #11 (**permalink**) 05-17-2005, 06:46 PM

JIM

MY CLEVELAND IDLES AT ABOUT 800 RPM , 25 OP IS 25 PSI------
AT 65 MPH , 2100 RPM RUNS AT 90 OP PSI

RICH

lovehamr · #12 (**permalink**) 05-17-2005, 09:05 PM

Filter wise, I still haven't found anything I like like the FL1-HP. You can tell it's got a stiffer case just by holding it in your hand.

Steve

blykins · #13 (**permalink**) 05-18-2005, 04:00 AM

I think I've heard before the burst pressure of an oil filter is around 120 psi.

trularin · #14 (**permalink**) 05-18-2005, 04:40 AM

I just switched to the Bosch.

Last night I got to take it out and I now have an idle PSI of 40. That's still running the 1100 RPM.

Yes, it seems the oil filter has something to do with it.

Jim Barnett · #15 (**permalink**) 05-18-2005, 05:21 AM

THANKS again for the oil filter change-out tips!! I'll certainly give that a try in the very near future!!!

rdorman · #16 (**permalink**) 05-18-2005, 06:02 AM

Perhaps a little low. Mine idle around 800+ with 25 psi no matter how hot on 5W-30 Mobil one. About 55 pounds at cruise in the 3300 neighborhood. For filters, I generally use either K&N or Purolator's Pure 1. Haven't really noticed any difference in them.
Rick