For a 2 bolt main 400 sbc that is driven only on the street with a cam making max power and shift points at or below 6000 RPM and compression below 11:1, what is a safe max power level? It would only see those "max" figures once in a while, and for a very short time. so what would be safe? What would then be safe for a 400 with splayed mains?

 

I race with several people running 2-bolt 400's. They advised that with ARP studs on the main bearing caps, a 2-bolt block will handle 450 hp run after run with no problems. If you use quality hardware to assemble the short block, I don't think you would make enough power with a "street engine" to find the limits of the 2-bolt main bearing caps. With ARP bolts in the mains & rods, and a quality set of connecting rods, you'll have lots of room to build HP.

 

450 at the flywheel or the wheels? It is not too hard to make 450 at the flywheel. But you hear of a lot of people making more than that at the flywheel with a 350.

 

Mine makes around 450 at the flywheel and the mains are moving around a bit even with ARP main studs. I tightened up the registers a couple yrs ago and that seems to have helped. Thin bores are the next challenge with these blocks. Lots of them split.

If you want to make more than 600 hp, get a Dart block and be done with it.

 

so it is sounding like a splayed main block is really the only way to do a built 400. The main caps and line honing alone will cost around 500 though.

 

That's why you go right for the Dart.