I have searched the internet several times over, and I always find different answers to the same old question...what should your oil pressure be on a FLATHEAD V8? Now...what I want to do is start this thread to see what people actually have. Can you post your type of V8, Mileage, Type of oil, and hot/cold PSI idling and running, and what type of gauge you are using? (Also if you are running a high volume pump, please specify) For Example:
I am running a fresh 239 Flathead 8BA.
Engine has less than 100 Miles.
I run 15W 40 Delo Oil.
Cold Idle- 50#
Hot Idle- 25#
Cold Running- 65#
Hot Running- 55#
Every post about oil pressure has what people think you should use for oil, and what they have. They always say "My flatty has 40#" but they dont say hot or cold and what type of oil they are using. The more information the better!!
Last edited by flatheadkeith; 05-11-2014 at 10:44 AM.
Reason: Added information
I put a lot of faith in bobistheoilguy and I am of the understanding that 10#/1000 rpm hot is acceptable. I also am a big believer that too much oil pressure can be a bad thing from parasitic hp loss to washing out the oil at the bearings.
Just built a 239 flathead and am expecting 20-30# hot at startup on 30 wt oil. Engine is tight, the tight end of tolerance. I will repost here when I finally fire it up.
BTW, I also have a 8MC in an old Customline. An obvious transplant and it is in dire need of a rebuild. Still starts up fine and with straight 30W hot it will idle with 25#. It's running a cheap mechanical gauge from Autozone. If it didn't smoke, I wouldn't bother opening it up. Probably going to just pour Marvel in it for a few frequent oil changes and see if the rings unstick...
1947 car 239 flathead either original or very old rebuild.
mechanical S/W gauge:
cold @ idle is 80psi
warm @ idle is 20psi
cold @ running is 100psi
warm @ running is 50psi
Stock gauge on dash:
cold pegged @ idle
warm @ idle is 18psi
cold running is pegged
warm @ running is 47psi