Hey guys I need a little feedback from y'all. I have a 1970 Buick GS 350 with an oil pressure of 38-40 on start up and around 22-26 after running the car for about 15-20 minutes. The engine is about 8 yrs old. The timing chain cover was replaced during the rebuild. These oil pressure levels have been consistent since the rebuild. I've been told this a common reading for Buick 350 motors. The engine runs really strong and makes no audible strange noises. When I rebuilt the motor the oil pump came with multiple application springs. I tried a few of them but it was suggested then to avoid anything other than the correct stock spring because the oil will break down in viscosity very quickly if I were to use a higher pressure spring. My motor is stock other than a very mild cam, headers, 2004r w/ posi 3.64 gear and I decked the heads .015. This last oil change I've switched to synthetic oil 10w40. I was running 10w40 in it since the rebuild. A friend suggested the oil pressure was too low and I should install a higher pressure spring to kick it up a bit. The car is a daily driver and other than a future trip at some point to the track on a Friday open night at the track in Baytown to find out it's e.t. I don't plan on racing it except the occasional 5.0 that needs a little spankin on the by. What do y'all think?
Hey there, Sounds like a really nice combo. No there is no problem with your oil pressures at idle, lots of people would love to have that for pressure. What you do need to be sure of is that the oil pressure raises to about 55 PSI when you rev the engine to 4000 RPM. I have always used 10W30 oil with good results. I adjust the oil pressure by using different viscosity oil, I just add some 20W40 if the pressure is a bit low. When yo take your trip you should record your MPG, I bet you could get 21!
Your pressure readings sound fine, Im assuming you have the stock relief spring in the pump judging by your cold pressure readings. I have to ask, you say your hot readings are after 20 min. of running, do you mean sitting there idling, or after 20 min. at highway speeds. Reason I ask is the oil will only get warm idling, versus hot after a freeway run for 20-30 min.
X2. to get your maximum oil temperature requires a sustained highway run. The important thing is that oil pressure rises with RPM, and that you have at least 10 psi/1000 RPM. If your transmission shifts at 5000 RPM, you want to see at least 50 psi at that RPM.
Yeah! Thanks for the response. The pressure reading is after a the 20 mile trip to work. The trip consists of 7 red lights and 15 miles of hiway driving at 70 mph. Very consistent at 22-24 psi when I'm parked in the lot at work and gathering my thoughts at idle before I shut her down. ---------- Post added at 12:44 PM ---------- Previous post was at 12:29 PM ---------- Thanks for the response...I've never seen the pressure go above 45 psi in any situation but my eyes are usually on the road when I'm hit the gas. I'll give that a look and I'll let you know. In park when reved to 4000 it's at around 40 and when I goose the thottle it will jump to 45 but never to 55. That's just a psi I've never seen it achieve. I've done some preliminary mpg equations but it's never been a whole tank at 70-75 all hwy miles yet but what I keep coming up with is 21 mpg. This is through the first 3 tank fulls. When it gets cooler I plan on a trip to Dallas and back on a day drive to get a better estimate on the mpg. The set up was designed to reach that 21 mpg. So far I'm exteremly please with the combo.
First off stop listening to anybody who tells you stuff like the spring will "break down" the viscosity of the oil. They have nothing to do with each other. If your oil breaks down it is time for an oil change to another brand because you have junk oil. You never mentioned what your oil pressure is when hot at WOT at higher rpm. Most people would kill for the oil pressure you have at hot idle. As was said 50 psi hot would be fine, extra doesn't hurt. The stock spring you are mentioning would limit pressure to 40psi so make it easy and just install the white spring that came with your kit. That should get you up to 60 psi at high rpm and your idle pressure won't change. That is the standard Buick issue Stage 1 oil pressure spring if you are using the original style oil filter mount. Maybe then you could try some 10-30 in there but there is no rush to change the oil.
Good advice Mike Thanks. The best I've ever seen was 45 psi. I was going to ask next, what color spring would be best. I have read in other threads the white spring was for the Stage 1 but I have learned over the past decade...the more input from others who have real experience...the better I can make an informed decision so Thanks again. ---------- Post added at 01:11 PM ---------- Previous post was at 12:58 PM ---------- The extra springs from the oil pump kit were lost in the Ike flood of 2008. Does anyone know if you can buy these at local parts houses or do you have to buy the entire oil pump kit? ---------- Post added at 02:58 PM ---------- Previous post was at 01:11 PM ---------- Found the springs at Summit.
I haven't taken it out for a sustained hwy drive yet but the white spring boosted my cold start oil pressure to 60 psi. I'll update as the other readings come in. Can't drive it this week due to minor adjustments needed for the adjustable upper trailing arms. I have to add spacers to align them correctly. They tow in about 3/4 of an inch so I had a local machinist make some spacers so I don't trash the frame bushings.
The white spring cold start 60 psi. After a sustained 30 minute drive on the frwy. The oil pressure...while in drive but not moving is now 37 psi. In park it is 40 psi. Thanks to all for the help!! I'm gonna call it good!:grin:
