They were a high performance factory inline six. I believe the 4 barrel version was rated at 250 hp. Overhead cam, forged crank, factory header, around 10.5:1 compression from memory. Freind of mine had one in a 67 firebird with a 2 speed automatic. The thing would wind up like a banshee.
They had cam troubles if the break in proceedure wasn't followed very carefully. Available for a very few years, I'd supposed in the 60's horsepower wars with 427's, 440's, 396's and the like that no one got too excited about a souped up pip-sqeak. Too bad.
