Details for 12550313
Manufacturer Chevrolet
Category Engine Blocks
Type Big Block V8
Date 1991+
Notes 454, 4 bolt, Generation V crate motor,
Generation VI 4.25 bare block, fuel pump boss
More info if you are interested...
No Gen 5 has a fuel pump boss. Gen 6 crate and service blocks do.
Gen 5 timing covers LOOK like MK IV but are different at the pan seal.
Gen 6 timing covers only have 6 bolts. Gen 5 and MK IV have 10,
The lifter bores on the Gen 6 are approx. .300 taller than MKs and Gen 5.
Be very careful if you are considering a flat tappet mechanical cam for a Gen VI ...lots of areas where it can go very wrong...hyd roller is the way to go IMHO
