oil pressure 455 pontiac

[E30M30]

Hi
I've recently rebuild my engine
I decided to go with the high pressure oil pump 80 psi (Mel-54f). Now I'm worried whether the pressure is to high or not. The engine has done 700 miles since assembly. I'm running 20-50 oil. Pressure is 30-40psi at idle (hot engine) and at least 80 psi at 2500-3000 rpm. Over 3000 rpm pressure is off the scale (+100psi) Is it acceptable or should I use thinner oil, or change the spring in the oil pump?

Thanks from Denmark!
Stefan

[Roadrage David]

Stevan im a pontiac freak myself you oil presure is way to high.
20/30 psi warm/ stationair in the standerd. then 10 psi for every 1000 rpm.
If you have a tight clearense engine and its cold weather go for a 10w40 oil.
If you have a flat tapt cam and higfh performance make sure you use high zink(zddp) contense oil.
try to use a mineral based oil like Brad Penn!!.

[ArtosDracon]

If you can remove the pan without having to remove the engine, I would get a hold of the pump manufacturer and get a low pressure spring for it. If not, I would definitely drop to a lighter oil. My truck has a high pressure pump and I don't quite make it to 80 when cold on 10W30 and I despise that it runs that high, the only reason I haven't changed it yet is because my S10 makes it obscenely difficult to pull the pan, it basically can not be done with the engine in the truck.

[Roadrage David]

No need for that i got the high volume pump as wel, thinner oil is all it takes to do the job, he probely did not widen his oil channels in the blok witch means also more oil presure, and sins he is from denmark and im from the Netherlands(very close),
i know his outside temp is the same iven colder then overhere.. 10w40 wil do the trick iven 10w30 when winter sets in..

[Zee]

I run the 80 PSI pump and call BS on the lower pump recommendation. I have 30psi at idle and 75PS or so most of the rest of the time. When cold, I am over 100 but I always let the oil temp get to 180 degrees or so before driving. Anyway, this 10psi per 1000 rpm thing was started off by Smokey Yunick who was racing Chevolets at the time. A Pontiac 455 main Journal is nearly a inch larger in diameter and when you are talking about only 2.45" or whatever to begin with, an inch is a huge difference. Same deal with the rods.

Pontiac knew this and most Pontiac enthusiast trust that the factory knew what they were doing as about the only aftermarket part that clearly outperforms the factory parts for Pontiacs are cylinder heads. So Pontiac when they developed the SD455 decided they needed more oil psi. To do so, they developed a new pump, which in turn required a new drive gear spec, Which in turn required a remachining of the block, different cam gear, different manifold and different distributor. All just to run a 80psi pump. Seems like a lot of work for something the factory engineers felt was unnecessary.

To add insult to injury, most Pontiac folks run tight bearing clearances. Take a look at Clevite's recommendation for bearing clearances X journal diameter and you will see most Pontiacs are way tighter than recommended. This may be why a lot of engines get away with the lower psi oil pump but IMO, between the tight clearances and the low PSI pump, is also why there is a daily posting on PY about somebody spinning a bearing.

Do what you want but my guess is your bearing clearance is too tight. Many use the 60psi pump and do just fine with it.

[wmhjr]

I agree with Zee. I'm also running the Melling 54 pump and the Melling pump shaft. Both were blueprinted, but effectively they are what they are. I'm running a small journal 400 block to start with, as I prefer the small (relative to Pontiac, not chebby) 3" journals given a choice than the 3.25" journals of a 455 block. You can't apply everything from other engines to a Pontiac motor. Something else is going on if you're over 100lbs of oil pressure at higher RPMs with 20-50 oil when the motor is hot. I would NOT go to a lighter spring. You may just mask the real problem by dealing with the symptom, resulting in destroying your engine.

[critter]

I've run both. After the last freshen up I went to the 54-D (60 psi) pump. Both have worked well but I fought leaks at the oil filter with the SD pump. I know many who've complained of the same problem. I saw photos where a high speed run on the 80psi mushroomed the filter. Crazy stuff. Of course that was probably the filter manufacturers defect.

[Zee]

Next I refer you to exhibit A:

https://static1.pt-content.com/images/pt/2010/10/fig6-1.jpg

[E30M30]

Crank, rods and bearings are new. I've chamfered the bearings. According to Jim butler the figures are allright for a performance engine.. I'm still going for maybe 10W40 oil to see whether figures will change. The engine survived a track day with th e oil pressure :)

[Roadrage David]

belive me 10w40 wil do the job. i also like to ad that thicker oil for more oil presure is also way overated and gives a fals feeling of sucurety, witch is the fact why manny a Pontiac injun block spun bearings!!!!.
Simple to the fact that a high volume oil pump is pushing against ""Thicker"" oil with means ""lesser"" oil flow with means ""lesser"" lubrication withs means ""more"" heat!!!!. combined with the larger 3.25 inch main bearings means bearing ""speed"" is bearing failer.
The pontiac 3.25 inch main bearing is notories for that.
Hensh the rezen why the beter engine builders use 3/4 grove bearings and prefeur the 3 inch main bearing 400 blocks and stroke them to a 461ci. and modify the oil channels in the blocks!!!!...
anyway Thinner oil means ""more"" oil flow means ""more"" lubrication means ""less"" heat means ""lower""(the right) oil presure when working with a high volume oil pump !!!!!!!.....