[Chevy454]

LOL...you know, these engines *will* actually run, and better yet, they'll even *perform* using the bone stock exhaust manifolds. I regularly see guys post dyno numbers of engines with headers comparable to numbers I've seen for engines with exhaust manifolds, same builds, etc, and all that tells me is the headers are just a band-aid for something else...

We built an L72 for Pure Stock years ago...we rebuilt it to "as delivered" specs, as I wanted to see exactly what a factory L72 would/could do. So, that meant crappy TRW pistons (28cc dome where it's supposed to be 34cc), uncut heads (110+cc chamber where it's supposed to be 105.9cc), didn't deck the block (pistons were all over the place, probably averaged .014"+ down in the hole), original rods/crank/etc, factory blueprint cam...all of this sloppiness got us barely 10:1 compression. Ran it through the stock exhaust manifolds, and it would pull between 425hp and 430hp on the engine dyno, so around 1hp per cubic inch...this engine carried our stock Camaro to mid-12s @ 108+ at a 3750lb race weight, on F70-15 tires. Now, my blueprinted L72 I did the following season, same intake/exhaust manifolds, same carb/ignition, same factory blueprint cam, etc, just a blueprinted long block, soundly put 50+ hp on the first L72...through exhaust manifolds.

So, as delivered, with a simple going over of the jets/timing I'd say you're looking at 1hp/cu-in, or somewhere around 395hp-400hp...blueprinted, 450hp+ pretty easily (I know of a couple L78s that have done this).