O K guys here is the prob...
I have just installed a 225 in my truck 87 D150 and the engine is out of a 69 Dart. The car sat not started for 25+ years. It is in and running and I have a low oil pressure problem. The stock gage reads 2 1/2 bars warm @ 2000rpm's and just under the L @ a 650-700 idle. So I figure it needs an oil pump, the engine sounds GREAT, NO bottom end noise at all. So I guess what I am wondering is do you think its an oil pump problem, and if so what pump should I go with...stock, HV or HP...and if not what do think the problem is...I am running Wolfs Head 20W50 & Hastings

PS: Money is tight, I need my truck, and I work the hell out of it 390 rear
I don't mind spending the extra money on a better pump if need be
The oil pressure sending unit is fairly new and worked fine with the 300,000 mile engine, not much oil coming up to the top end

Thanks for your help again in advance

It will be a good idea to service the oil pressure relief valve to make sure it's doing its job, as described in these two threads: thread 1, thread 2.

If that doesn't bring up the reading, put a mechanical pressure gauge on the engine to see what the actual oil pressure is. If the engine's in good shape, the oil pressure will be good. If the oil pressure isn't good, the engine probably isn't in as good shape as might be thought.

If the engine's in good shape, 20w50 is way too thick an oil; using it is a good way to shorten the life of the engine greatly and quickly. go down to at least 10w30, preferably 5w30.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

O K thanks, in the stock unit, if I wanted to increase the oil pressure would I go to a stiffer spring or a looser spring?

A releif valve spring change will not help low RPM pressure readings, it is a high pressure "by-pass" only. The stiffer the spring, the later (higher pressure) before it opens.
The valve is fully closed at idle and into the 2000 to 3000 RPM range, then it starts to open as the pump produces more pressure then the engines needs.
If you truely do not have oil pressure at low RPMs, there is a large leak or "bleed-off" in the oiling system or the pump has a problem.
Was any work done to the 69 225 before it was installed or is it a used engine, built by the factory?
DD

Im with Dan, never rely on a stock gauge when you have an issue like this, always put on a mechanical gauge as a backup to verify what the stock gauge is telling you. Then you will have an actually psi to match your idle pressure and cruise oil pressure instead of just a needle pointing at an L. If it sat for that long prior to you installing it and getting it running, its likely you don't know the condition of it before it was parked. It could have been "rode hard and put up wet" so to speak and be needing a rebuild.

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There's no such thing as too much cam....only not enough engine!

I agree with Dan,a stuck oil relief valve is the first suspect. You could check for a striped drive gear by removing the 5 bolt pentagon shaped cover,rotating the engine by hand,and checking for movement. Also,did you change the oilpan and pickup to fit the truck?

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V8?? We don't need no stink'n V8!!

I will be checking the oil relief valve first. I do not think it's a stripped gear or I wouldn't have any oil pressure at all, right? I did change the pan and the pick up tube, so I could put it in the truck.
Thanks

Well I pulled the relief valve ass. apart, there was quite a bit of gunk around the spring, I cleaned it up good, put it back together. I started the truck up and it seemed to have better oil pressure for a little bit, but once it warmed up it fell off to nothing. I found a mechanical gauge and I will be checking it tonight.