455 performance

[Guest]

What parts are diff. on a 1970 455 from a '72 455 that make all that extra horsepower and what can I do to my '72 to give it more balls because right now my electra just isnt cutting it. <img src="http://www.aaca.org/ubbthreads/images/graemlins/confused.gif" alt="" />

[The Old Guy]

There are two major differences.The first is compression. The 70 has 10.25 to 1 an the 72 has 81/2 to 1. The major change was the way they were rated. The 70 was a bare engine( driving no power accessories and headers instead of manifolds). They also ran the 72 with retarded timing to make them pass emissions

[Turbo Loyd]

[color:"blue"]According to the NHRA website:

http://www.nhra.com/tech_specs/engine/index.html

The 70 engine had 16cc dished pistons and the 72 engine had 28cc dished pistons, both heads had 59cc of volume except the 70 stage 1 had 55 cc.

As Old Guys says the gross versus net evaluation method made all the HP figures look pitiful.