Like the title says, what's the correct engine inclination angle when pinion angle doesn't matter, ie SBC attached to Audi 01X transaxle in north-south orientation? I'm thinking horizontal, but I'd like to hear your reasons if you disagree. FWIW, there are no suspension links attached to the transaxle, and it will be mounted so the halfshafts are horizontal at ride.
Whatever lets you get it the lowest in the vehicle? I guess I'm assuming that if it's not wildly canted you won't have oil drain issues...
I have it in my head that CVs are happiest if they have a *little* angle so the balls aren't wearing the same spot constantly, but I suspect there's enough movement to prevent that from being a big deal unless the car's going to spend a ton of time plowing along a billiard table, right? OTOH, I also don't think I'd be so worried about CV angle that I'd take straight CVs over lowering the trans a little (assuming clearance)?
Just what comes to mind, no opinions with much conviction.
Sort of matters what the planned usage will be. If racing, then i would lower the transaxle a bit for better CG even with a little angle on the halfshafts.
You really don't get that much CG improvement tilting the front of the engine down. I'd vote horizontal. Probably for visual reasons and thinking thats the way all the engineering was developed, especially in the case of oil paths from the valve covers down to the pump.
Level across the intake surfaces at front and rear of block. Intake on you can probably put your level across the fuel rail bolts.
Lubrication would be my main concern. Stock pan or modified? Different than stock capacity? Dry sump or wet? Oil acumulator?
If the engine was designed to be on a tilt using a traditional wet sump changing the angle of that tilt might cause unexpected consequences like aeration or cavitation under extremes.
Stock oil pan, engine is LT1 out of 1994 Corvette. I'm going with horizontal and bottom of pan about 8" above the ground, which I think is 2" higher than as installed in the C4, mainly due to stub axle heights. I will make it as low as I can within the confines of the C5 frame and suspension cradle.
Given its intended use, you'll likely see higher braking G's than acceleration or lateral. So being rear-sump if you tilt the nose downward you'd have a slightly higher likelihood of exposing the pickup under hard braking.
Otherwise I don't see it making much of a difference.
I always thought you wanted the intake manifold level at the carb hole.
American Iron engines are usually installed at 2-3 degrees nose-up.
Chevy had coolant bleeding issues on some Corvettes when they installed them level. The cylinder heads had areas where air would collect since the front of the heads was no longer the highest point. OTOH the LT1 was designed to be installed level in the C4 so you should be fine. I would think that having the axles straight would make the drivetrain sit very high up unless you are using little 22" diameter tires, though.
Notice that the LS engines, which were first seen in Corvettes, have air bleed passages at all four corners. LT1s were notoriously hard to bleed the air out because the water outlet was not the highest point of the block in the first place, so Chevy engineered to the other extreme 
If you use an airlift to fill the cooling system then you probably will have no issues. An airlift pulls the cooling system under 27-28 inches of vacuum and gets almost all of the air out of the system before you add coolant.
I would not worry about oiling. A couple degrees difference in angle means nothing compared to acceleration and braking forces.
Yeah, if all else equal I'd shoot for the inclination of the engine in the car it came out of when sitting on level ground. But I'm thinking you'll have a bit of leeway no matter what happens.
I with thirdtwelfth the close to OE donor angle ish idea for coolant bleed and oil supply with OE pan.
if using stock pan and dipstick, engine inclination could change your indicated oil level by a lot.
Oil drain back from the heads will be the issue with the angle you need to set the motor at. Look up what the stock angle is and go with that.
I recently put an engine in a car it didn't come in. It's a front sump engine and I modified the pan to get the motor lower, but made sure the flat part still sloped to the sump when the engine was level on top, as it was originally installed in the donor car. The water outlets are at the back of the heads. I'll have to look at my spare heads to see if they are at the high point, or if I have to do "something special" to have a high point vent in each head.
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