What would make oil pressure drop while accelerating. I just did a motor swap, and it has a new oil pump, with a fresh oil change. While I'm driving my oil pressure is about 20 on an aftermarket gauge. When I accel hard, it drops rather than raises. I have no leakes. Whate next?

 

What are your bearing clearances?

 

How many miles on the new engine?
First try with another gauge and anothe sending unit.
Though it is uncommon The pump may be installed improperly or the pump is defective, check that it is mor easy, if not check the bearings

when is the oil psi whenyou just start the car? (car cold)
what oil are you using? (10/40? 20/50?......)

 

the psi is at around 50 cold, and I'm using 10/40 not sure of the bearing clearences, but when I first installed the motor, the oil pump was reading a steady60 psi. the short block had approx. 120000 miles on it and the rest was newer, except the upper and lower intake

 

First, sorry if my spelling is not perfect, english is not my first langunge.
Well 120,000 is a good reson to belive your lower engine need a rebuild (lower engine= crank,main bearings,rod bearings, oil pump) but ther are a few things you can do easly and it may help you to use this engine longer:

1) As I said befor, make sure you are not getting a false reading, if the gauge was improperly installed it could give a false reading, I understand it is new, may be you got a defective one, it happen to me with a Vac gauge giving me the rong nombers, befor I did anything I chacked with another gauge and I saw every thing is ok, so there is a chance you dont have any problem at all.

2) A well known fact is when the oil is could it is thick and heavy, thicker oil will build more presure, this is whay you have more pressure whan the car is cold (cool engine) , whan the oil is hot (in working temp) it is naturally thinner and the pressure will go down.
therefore if you will use a thicker oil, your oil pressure will be higher, I recommend you to use 20/50, you will see the change. In my 5.0, using a 20/50 the oil preassure in (when first starting the car) is 75PSI@800RPM, and about 100PSI@3000RPM after a good warmup it is naturally going down to 45PSI@Idle but still going as high as 75PSI@ 2500RPM, this is very good oil preassure and it is like this 12,000 miles after installing the new bearings.
So try to change the oil to a higher viscosity (20/50) to have more oil preasure.

3)The Oil Pump is operating by the oil pump driveshaft comming out of the distributor, it might be worn, and maike your oil preassure drop when it shoulde turn fast. you wrote the oil pump is new, if it is new and the shaft is old it could be a good reson for that to happen. the shaft is cheap, you can get it here http://store.summitracing.com/partde...p;autoview=sku.

4) You wrote the oil pump is new, but did you replace the pumppickup as well? some times the oil pump pickup has a crack or a dent and it will interfere the oil pump, or the gasket of the pickup is pluging the oil flow due to improper installation, check it out and see... you can get it for cheap http://store.summitracing.com/partde...p;autoview=sku

5) If all of the above is checked but still low oil pressure, consider arebuild soon cause you need about 10PSI for every 1000 RPM the, 20 is to low
hope I helped
Good Luck!

 

I don't believe the rod was replaced, So I'll look into that. The pickup has been replaced. I'm gonna run the thicker oil, and maybe I'll throw in some seafoam as well. You have definietly helped, and your spelling was almost perfect. Cheers and I'll keep an updated post on this. Thanks