Another opinion question

The overall output will be similar on each build (not exact, but similar). The longer the stroke of an engine, if all else is equal, the lower rpm peak power will be made. as an example..think of 3 engines. all identical in every detail, running stock heads, and valve sizes, cams, carbs, you name it. #A is a 340. 4.07 bore, 3.31 stroke..it's dyno'd and the power is 375hp at 5600, 370tq @ 4200. #B is a 360, 4.03 bore, 3.58 stroke..dyno'd and power is 370hp @ 5200, 395tq @ 3800. #C is a 408, 4.03 bore, 4.00 stroke..power is 380hp @ 4800, and 430tq @ 3200. These are off the top of my head, to illustrate the differences. Th big bore size will give the 340 a small boost from less shrouding, but the power peak is highest in the rpm range because the piston speed is slower until the rpms come up. The 360 has a longer stroke, but the smaller bore by a bit, so the power will be down slightly overall, but the peaks will also move down in the rpm band, because the longer stroke has a higher piston speed at the same rpm than the 340. The 408 lowers it a lot more, and makes the identical cam the 340 ran well with feel like an rv/truck cam. The piston speeds are much faster in the same rpms, so the power bands are that much lower (also a reason you see forged pistons primarilly used in 408/416s. The pistons speeds get too fast for a cast or hyper if you're really spinning it.) The 408 will pull like a freight train from idle..the 340 will need a higher stall and gears to get the best results. Make more sense? there's a lot more, it's not this simple, but at least you can get the idea.


Personally, aluminum (Read as Edelbrocks or Commandos) heads will run better on the 4" stroke than most iron heads. You'll spend some $$ to get irons to work as well, and some are better at getting numbers from them than others. The irons will work for any build, but I'd say they're better on the 340/360 deal.