The 351 Windsor officially debuted in 1969 and 4 barrel versions of the 302 were subsequently dropped. By 1971 emissions regulations began robbing horsepower from the once mighty small block. With reduced compression ratios and the addition of mechanical smog devices, the 302 managed to only pony-up 140 HP in 1975. In the mid to late 70’s, small block performance stagnated among factory built 302’s. The engine was rated at 250 HP with a 2 barrel and 290 HP with the 4 barrel. The 351W has a taller deck height to increase the stroke. While all 289, 302 and 351 Windsor’s share a 4″ bore, the 351W engine had many changes that set it apart from other Windsor engines. The intake, heads, pushrods, block height, and firing order are just a few of the more notable differences between the 351W and other 4″ bore Windsor engines.