Sure the oil pump drive shaft is fully engaged?

Since it has pressure at start-up, I would be looking at stuff like the oil pump pickup being too close to the oil pan, or something else restricting oil intake into the pump.
Or the pump itself.

Hang in there!  You will make the bash!

When I first installed the engine, I was adjusting the valves. I heard a loud sharp crack type noise when I was turning it over by hand. At the time I assumed that I didn't have a pushrod correctly seated and it snapped a valve shut, so I kept on going. That's the only thing I can associate with all this trouble.
I bought a new oil pump and used the same drive shaft. It's a heavy duty ARP shaft. The new pump came with a new shaft, the lock washer is in the same place on both of them. I put the shaft in the pump and then installed it. It won't engage if you put it in from the top. The new pump is the same depth (length) as the other one. Im using the same oil pan that I have for the last 4 years.
I used my drill motor to build up pressure again this morning and fired it. The pressure came up to 40 and bled down fairly quickly as it warmed up. I shut it off at 20 PSI and am now disassembling it. The cam oil galley plugs are the press in type. They were replaced the first time around with the new cam bearings.
  I would need to have a block machined for the stroker crank, squared up and punched, so to machine it for the roller cam would be done at the same time. Are you thinking I should go ahead and install the shortblock as is till after the bash? I'm not sure I would trust that move? I would think it would run pretty crappy (rich) with the carb I have??.

Just wondering if it could be a cam bearing clearance issue. Cold startup and only 40 psi seem a little low to my thinking.

Gary, you know the noise you hear when you smack the valves on your Lycoming to get them to seat when doing a compression check. It was that same type of noise. I reinstalled the same bearing brand and P/N as was originally put in it. I didn't do a plasti gage check because the machine shop supplied the bearings after doing their thing to the crank and rods. If it would have failed their plasti gage check they would have supplied different bearings.
red351, The machine shop installed the cam bearings and supplied the cam so I never checked it. I'm thinking loose bearings would always have low oil pressure to start with. The 40 lbs is at initial start up at idle. I was able to get it to 60 lbs with my drill motor. I haven't reved it up yet. Little fraid to do that.

HudginJ3 wrote:

Gary, you know the noise you hear when you smack the valves on your Lycoming to get them to seat when doing a compression check. It was that same type of noise. I reinstalled the same bearing brand and P/N as was originally put in it. I didn't do a plasti gage check because the machine shop supplied the bearings after doing their thing to the crank and rods. If it would have failed their plasti gage check they would have supplied different bearings.
red351, The machine shop installed the cam bearings and supplied the cam so I never checked it. I'm thinking loose bearings would always have low oil pressure to start with. The 40 lbs is at initial start up at idle. I was able to get it to 60 lbs with my drill motor. I haven't reved it up yet. Little fraid to do that.

Years ago I advised a coworker on a rebuild of a 454 BBC for his boat.  He was working in our shop after work and I asked him what his bearing clearances were.  He looked at me blankly.  So I asked if he checked them.  Blank look again followed by "the machine shop turned the crank and gave me the bearings I'm sure they're fine".  Well, it wasn't fine.  After reinstalling the engine in the boat and hearing it run for 10 seconds it was pretty obvious that it wasn't fine.  On disassembly the engine was trashed inside.  Seems he had a crank turned 0.010 under and stock sized bearings.  Not a good match. 

Obviously, this isn't what happened or you'd see indications of it, but its why I do not take ANYTHING for granted that comes back from the machine shop.  "Should've" and "did" are quite different and "should've" costs you money, sometimes a lot.Yes, they're machinists, but also human and they make mistakes, or assumptions that turn out to be wrong. 

Point being, a quick check with plastigauge is never a bad idea.  It might be worth a quick check, if nothing else it rules out sloppy clearances. 
 

The whole process has been nothing but a bucket of frustration. I'm going to start completely over again from scratch checking everything methodically as I disassemble it. I'll come to a conclusion before I reassemble it or go after another block.
The bearings are the same manufacture, part number, and even model? number. That however is misleading because one set of bearings had the oil groove all the way around and an earlier set didn't. That didn't effect the oil pressure though. If there is a crack in an oil galley I would suspect in a cam bearing area.
I asked questions about the cam followers, there is not supposed to be a need for any changes to the block except where the "bones" need to lay flat and to drill and tap holes for the "spider" hold down screws.

Are you saying you installed a roller cam in a non-roller block?   That is fine if correct aftermarket lifters are utilized, or if a reduced base circle cam is utilized.

Roller blocks are defined by the raised lifter bores that allow the longer roller lifters to remain within their bores even though they sit higher on the cam.

That said, if using stock Ford type roller lifters in a non-roller block, it is possible the lifter oil passages no longer align with the passages in the block.  I would think that would result in horrendous valve train noise as it lost oil pressure, though.

Are you getting alot of valvetrain noise as the oil pressure drops?   Once on a 302 I had, a piece of teflon tape got across the hole in the end of the oil pressure sender so the gauge went to zero.  The lack of valvetrain noise told me I still had plenty of oil pressure.  Temoving the tape cured my loss of oil pressure.

I apologize I have not read every post, so hope I am not asking questions already asked.

I wish we all could camp for the week at your domicile. With all the brains we have here we could figure out the problem, drink some beers and have a good time.

RV6 wrote:

I wish we all could camp for the week at your domicile. With all the brains we have here we could figure out the problem, drink some beers and have a good time.

This bucket of frustrations may not seem so bad compared to all of us camping out for a week at your place  to "help" you fix it. 

We're pulling for you Doug. 
 

I hope this is what your after. Let me know.

OK, I didn't know what you were looking for. That is a new gear on the dist. It has been run no longer than 10 minutes. I changed it because it was not compatible with the cam gear. The cam gear is what is worn. It has maybe 3 miles on it, and fot he miles it pretty well worn. The machine shop says it's OK. The wear is about as much as your or my finger nail is thick.  The oil pump shaft is the new one that came with the new oil pump. I'm using my original one because it is more heavy duty. The star washer is in the same place on both of them and I inserted the shaft from the bottom up when I installed the pump. That's the only way it will fit. 
I heard that the lifters for early blocks are different than the lifters in the newer blocks. I did a little internet research and I think I found that to be true. The machine shop is working with Comp Cams to verify, I think their catalog might be wrong I hope. ??? 

I don't know the answer to your question 6, I didn't pull the valve covers with it running. I only pumped up the oil pressure with my valve covers off with my drill. That was pretty messy as it was. I think it would go higher but my drill can't handle it and quits. Ill find out the results of the investigation tomorrow or Thursday and go from there.