360 to a 408 how much quicker
Also, just for those that may not be aware, NHRA and IHRA Stock Eliminator have different rules than IHRA Crate Motor. "Stock" intakes and stock lift w/ any duration cams in Stock. "Stock" heads in Stockers, too. I was a NHRA Stock Elim racer for a while, I'm not familiar w/ Crate rules. Maybe Myron can fill us in some.
The main differences between "regular" Stock and crate motor Stock is that CM combos are allowed any unmodified, over-the-counter intake and a unmodified Holley or Quik Fuel carb. The carbs must come with a choke tower & plate. 750 for small blocks. 850 for big blocks. (Most don't come with carbs and the ones with manifolds tend to be flanged for a square bore carb.) Also, piston deck height is .035" including gasket across the board (to simplify things). Other than that, all of the IHRA accepted crate motors have manufacturer blueprint specs that need to be followed just like a "regular" Stocker. In my case, the 360/300hp Commando (factored to 320hp) cam spec is a hydraulic .474" lift., flat top pistons with 2 notches, OEM heads w/1.88" intake & 1.60" exhaust, + .015" stroke allowance, .070" max overbore, etc.
The original intent was to provide a less expensive way to get involved in class racing while using factory speced engines. No need to hunt for rare, expensive manifolds & carbs and heads are more modern and plentiful.
You can also build them from scratch, provided you use the appropriate parts, since some are no longer available as a whole. Most parts, like cam, rods, pistons, valves, etc. are swapped out for legal aftermarket parts anyway in any Stock class.
This was the main reason I got into class racing. I know nothing about Carter carbs and the Mopar combos have been so popular and refined over the years, resulting in some very fast cars, that I would have been a slow moving duck for any heads-up races. At least I knew how to tune a Holley from my bracket racing days.