64 barracuda 273

When hp ratings went from gross to net, 318s went from 230 gross to 150 net, despite everything being the same - CR etc. 340s only dropped from 275 to 240 despite losing two full points of CR and having smaller intake valves. From that, I'd guess the 318's gross hp rating was a lot more optimistic than the 340's gross rating, and that 66fs's 318 horsepower guess is pretty accurate (#14). And from my own personal experience, the 340 I put in my 65 Barracuda back in 1973 was a lot more than 40 hp stronger than my original Commando 273.

273s, 318s and 340s all shared the same 3.31 stroke. 273s are no more of a revver than the other two, equally carbed and cammed etc. But it will have noticeably less grunt down low.

I loved my Barracuda when it had a 273 in it, but when I blew that up at 150K (trying to drive 200 miles in second gear after breaking my 3-4 shift lever inside the trans) the 340 I dropped in impressed the you-know-what out of me.