my ho has forged crank, pistons and rods they are all stock originals. another difference is the rod and main bearings are heavy duty and the valve train is also. the valves have duel springs instead of standard single springs on a standard 400 4 bbl. camshaft are also a larger duration and lift. than a stock. h.o also has factory headers the standard does not.
All 1968 Pontiacs other than 250 1 bbl have dual valve springs. That includes the 400 4 bbl.
YW has the same cam (9779067) as YT and WZ. It uses the same cylinder heads as YT, WZ, and WQ. It uses the same distributor as YT. It uses the same intake as YT, WZ and WQ. It uses the same block casting 9790071 as YT, WZ and WQ. It uses the same crankshaft 9795480 as YT, WZ, and WQ. It uses the same main bearing package as YT, WZ, and WQ.
The difference is the long branch manifolds for the auto 400 H.O.
Vikki 1969 Goldenrod Yellow / black 400 convertible numbers matching
