Ok I put a set of aluminium l98 heads on a 350 I took out of a chevy pickup truck I owned and sold it to a guy. Well when I swapped the heads I also installed a few other parts such as a new melling high yolume oil pump w/pickup welded on from summit a comp cam, a performer intake i had laying around and a edelbrock carb. Anyway the guy has someone break the cam in for him and during the break in the oil pressure drops off after a few moments(I don't know how long it took). So they shut the motor down and wait a few and try again. Same thing only pressure goes to zero. Well the guy has brand new gauges so I don't think thats the problem> They thought it could be the pump sucking the pan dry, which I thought from the way it sounds that could be it. Now they think that the bearings are bad. I don't know what to think because I drove the truck it was in for a few months with no problems at all. I beat on the truck and the motor never got hot never made any noise and never ran bad what so ever. The trucks oil pressure gauge did say I had no pressure at idle for awhile then stopped work at all so I was never worried cause the thing still ran great. So my question really is why on earth would a motor running at 2500 rpm for the break in lose oil pressure? Is it the bearings? I hope not cause that would be my fault.

 

The only way you're going to really know is to pull the pan.

 

Sounds like your old truck's oil pressure gauge was telling you something.

Or the brand new gauge on the new truck is defective.

Or you installed the new oil pump wrong. There are a few ways to screw up, my favorite shadetree error is using too long a bolt to hang the pump onto the main cap, mashes the main bearing right up against the crank and fills the pan w/ metal.

I'd hang a cheapo capillary tube manual pressure gauge on the engine before pulling it from the truck, and rule out gauge error before pulling the pan.

 

I don't think the bolt was to long because the pump came with a drive shaft and bolt. yeah I'm not working on the motor so I'm just gonna have to wait and see what happened.