You will find some significant differences in the way the two engines fit in the engine compartment.
Although the crank centerline of the 455 will be the same as the 403, the 455 is about an inch taller than the 403 due to the greater deck height. Hood interferences are likely.
Secondly, the 455 (big block) is 14 inches wide between the heads, while the 403 (small block) is 12 inches wide. Lateral clearances are going to be tighter.
Getting this measurement is the quickest way to differentiate between BB and SB Olds.
__________________
'67 Bonneville Sport Coupe, 428, auto, PS, PB, AC, an unmolested original.
|