Well, I'll have to let someone else jack up their motor by the crank snout. However, if I ever had any work done on MY engine by someone else (aint likely ) and they put a floor jack under the hub and started cranking on it, I'd be hard pressed not to smack the crap out of them. I view it the same as beating the hub on with a hammer (seen it many times, and cringe every time! Try to picture how much thrust that engine is going to end up with after being whacked on like that - who knows!) There are simply better, proper, ways to do things. And I'll stick by saying that jacking the motor up by the crank hub aint one of them...

I'll go ahead and get off this now so this thread can die a peacful death.

Dave C.

 

Talk about bringing up a classic. I thought I would pipe in with my experience.

First of I had my first rebuild at 90,000 kms. The engine lasted another 180,000 on top of that. Since day one, it did exactly what everybody else here is talking about. Above 4500 RPM in 1st and 2nd the pressure would drop SIGNIFICANTLY then come back up. 3rd or upper gears, it would be normal.

The engine was rebuild again and again did the EXACT same thing.

This time, I took it easy and dropped the pan to find out the wrong pickup tube was used (not the 3/4" tube and pickup). Once that was changed, and a high volume pump was put in, the engine responded 100% normal and never had the issue again.

However, I neglected to put a road race pan on it, and after 15,000 kms I'm rebuilding again.

Lesson learned: Use 3/4" pickup.

Now why are stock engines doing this?

 

The original poster's problem was the oil climbing the back of the pan. Without an aftermarket deep sump, with oil control devices or a angled plate in the back and baffle in the stock pan it will happen.
Usually a pump with a 3/4" tube is HV and I have not had a problem with them with a good pan. I have had guys with HV pumps miss a shift and go to 8000 with no damage to the engine. Sooooo I rekon it's a prerferance and it does take about 4HP as seen on the dyno. I have used an out of the box BBC pump for years but with the LT1 ya got to be careful with the plastic drive and/or bronze gears and make sure the gear patterns right and ya have the correct end play in it.
Ya need a good pan with it also. I have never built a performance build without a good pan. Some think ya can do it and are dumbfounded when it goes away after a few miles.

 

So does that mean LT1s use high volume pumps?

There are some pumps listed for the LT1 as 3/4" pickup and then another pickup? This is in a parts book and GM parts lookup.

 

The 5/8" pickup fits a SBC. The couple of factory LT1's I have torn down one had a 5/8 and one had a 3/4 pickup. I go back with the 3/4 and a pump that fits. If it's a HV then so be it.
On a performance build I use the BBC out of the box. If its a real HP motor I will have Clay Smith Cams make me a blueprinted pump for about 110.00.
All of this will depend on your bearing clearance's.