Here is some more info. I will only post info on the 383 only from 1968 -1972... I got this on the internet a while back, forgot the site..
In 1968, the 383 got a shot in the arm. While the two-barrel V-8 was downgraded powerwise, the four-barrel V-8 held its own or was upgraded in performance. The Super Commando 383 developed 330 hp at 5000 rpm and 425 pounds-feet of torque at 3200 rpm. Compression ratio was 10.0:1. The air cleaner was unsilenced and the engine used a dual exhaust. The most powerful 383 that year was a special engine developed exclusively for the low-cost Plymouth Road Runner and Dodge's equivalent, the Coronet Super Bee. Chrysler bumped the output of this 383 by bolting on the highperf ormance pa rts designed for the 440 V-8 used in the Plymouth GTX and Dodge Coronet R/T, introduced in 1967.
These high-performance parts consisted of redesigned cylinder heads having larger-diameter exhaust valves (from 1 .60 to 1 .74 inches), and recontoured ports. Heavy-duty valve springs and rocker arms were employed. The camshaft from the high-performance 440 was also used. Atop the engine sat a Carter AVS four-barrel carburetor and a new, dual-plane intake manifold. The air cleaner was unsilenced and the engine, naturally, used dual exhaust. The rating for this 383 was deliberately conservative; 335 hp at 5200 rpm with 425 pounds-feet of torque at 3400 rpm. In totally stock trim, the engine was capable of launching the Road Runner or Coronet Super Bee through the quarter-mile timing Iights at nearly 100 mph with an elapsed time of between fourteen and fifteen seconds. Specifications for this engine remained unchanged for 1969.
In 1970, all three 383's had lowered compression ratios. The twobarrel V-8 was now at 8.7:1, but it still put out 290 hp at 4400 rpm,as it had the previous two years. This engine could now run on regular fuel. The two high-performance four-barrel versions had compression ratios of 9.5:1 . Their horsepower and torque ratings remained the same, however, as did their premium fuel requirements. In addition, the 335-hp 383 was switched to a Holley four-barrel carburetor.
In 1971,the high-performance 383 was detuned. Both the two-barrel and four-barrel 383's that year had their compression ratios lowered to 8.5:1 to run on regular fuel. The two-barrel V-8 was rated at 275 hp at 4400 rpm with 375 pounds-feet of torque at 2800 rpm. The four-barrel 383 had 300 hp at 4800 rpm with 410 pounds-feet of torque at 3400 rpm.
This was the last year of 383 production. Over three million 383's had been built by the end of 1971. Thus, Mopar hot rodders looking for a cheap and plentif ul engine to bring back to life could do no better than the venerable 383.
In 1972, the 383 was replaced by the 400-ci V-8. The higher displacement was achieved by increasing the bore to 4.34 inches. The 400 V-8 was essentially a smog motor, having a compression ratio of 8.2
