oil pump driveshaft

I'm building a 377 and I think I remember reading something about needing a special oil pump shaft for a 400 sb. Any help would be appreciated.

Not that I'm aware of. If you use an aftermarket pump they often recommend using a quality all-steel, self-collared drive pump shaft but it's nothing that's different from a 350 or other SBC.

That's not entirely true.

The 400 is the only small block that requires a tapered oil pump driveshaft for clearance. A lot of aftermarket oil pump driveshafts however, already incorporate this taper so that the drive can be used in either a 400 or other small block.

I recommend you buy a one-piece chrome-moly drive, like the ARP unit. Use ARP PN#134-7901 for a 400 small block. Thats what I'm using in my engine, and it is a one-piece unit. I would not use a pinned-collar shaft type oil pump drive for any kind of performance work. It's okay for a stock engine and stock RPM range, but imo it's best to spend a few more duckies and buy a quality one-piece solid shaft like the ARP unit.

Dave