Something you don't see very often. This is a 400 inch SBC, factory cast iron block with four bolt mains topped off with a set of Pontiac heads. I don't know the full story on the heads, evidently Pontiac got into some kind of racing in the 90's where they needed a part number head in order to compete so they designed a 15 degree racing head for the Chevy block. I know a couple of hard core Pontiac guys and neither of them believed me when I said we were dyno testing a SB Pontiac. I had to send them pictures and they still didn't believe it.
The heads kick ass. They have big intake ports, spread exhaust ports, 15 degree valves, cast for Jesel rockers, and very tiny combustion chambers. This engine is 14:1 compression with a flat top piston. The intake was cast for a 4500 flange so you know they were serious about the airflow.
We had it on the dyno the other day and it made 675 hp on one of the first pulls. That was at 30 degrees of timing and the crankcase vacuum hadn't been turned up yet. So the engine might make 700 hp once it is broken in and has regular oil in it and full crankcase vacuum. Not competitive in NASCAR anymore but I bet it was 30 years ago when these heads were cast.
Anyway, just kind of cool to see someone drag some ancient heads into the dyno room and have it spin the needle over hard.