Not really. The oil passage is always exposed at the bottom - when the lifter is at the top end of it's travel. The base circle is usually only changed (made smaller) when the lift is so high that the cam wouldn't fit into the tunnel and/or the lobes would contact the lifter bores. A smaller base circle allows the lifter to sit lower in the bore but it still exposes the oil passage when it at the top end of it's travel. Otherwise, base circles of cams are usually in the same ballpark until they start getting crazy lift. FWIW that's why many race blocks now have much larger and even raised cam bores - lobe lifts are getting so high that making the base circles smaller exceeded the strength of the cams. Remember, high lifts require more spring pressure which is transmitted to the cam.

Let's confirm that the oil pump drive shaft is 7" from the tip to the bottom of the gear.

People keep overlooking the simple issue here, it works while NOT running but looses pressure while running! Somewhere a DOOR is opining!! Find that DOOR, IF no door, the drive shaft is too short or gear is slipping. That is the only thing that’s changed from the drill motor to engine running.

Exactly. It works with a long priming driveshaft but not with an undetermined length distributor drive. So, I'll ask again. Is it 7" long from the tip to the bottom of the drive gear?

Yup! And its been mentioned in a couple of replies.

Simple to check shaft, stick the drill drive into the pump, put a piece of tape on the shaft at bushing then compare to the gear-driver.

Sorry guys I haven't had time to look at it

On the intermediate shaft..i can plainly see it under the car..i have to have the female part of the oil pump, that in goes in the block, lined up with the intermediate shaft, or the pump isn't going to go in the block, right?

Uh, usually the pump is installed FIRST !!!

Let's go through this process carefully ...

The pump gets installed. The engine is rotated to TDC on the #1 firing stroke. The intermediate shaft is installed to put the #1 plug roughly where you want it when the distributor is installed. When you install the intermediate shaft it will self-align with the pump.

If the shaft is too short the pump will install without clocking it.

You can remove and install the pump from the bottom, but you will likely have to get the pilot started now then rotate the pump CW and CCW until the intermediate shaft engages the inner rotor. Not how things are usually done but no problem in doing it this way.

When I replaced pump back in the day I just rotated pump body a little till it slid on up, very easy only15 degrees each way (6 flats)

Exactly. Never been an issue.

Sorry guys ive been busy with work, and needed a break from looking at this thing..lol

Yes Rick the oil pump shaft is 7"

What's the clearance of the swinging pickup, from the bottom of the pan supposed to be? Mine is pretty close.

Maybe 3/16"

Alright, thanks Rick..that probably what I have, but seams like it scrapes in a couple places

I have a used Charlie's pan i bought here a while back, it seams to have way more clearance, I have attached a picture of it

Yes, that looks a little high. You can't use oil you can't pickup

It is very high, like 1/2"

That's an issue, but NOT the issue. The pickup sitting 1/2 off the bottom of the pan is not going to cause a loss of oil pressure at idle and allow you to build pressure with a drill. I will bet a $100 that your issue is oil getting passed the lifters when the engine is running. Pull the intake and valley cover, pressurize the oil system with a drill and crank the starter. You will see the issue. One question i haven't seen answered, is this a new build or have you had this running before?

This "may" be his issue BUT unless you have a trained eye you can't tell what's good or bad because there is a significant amount of oil seeping past lifters anyway. I'm speaking from experience also. Had a similar issue, swapped in shrouded lifters but couldn't tell the diffence - but it showed on the gauge !!