318 variances

[hemitheus]

I understand that the gas crisis and government regulation was a ***** back in the day but what was so different in the engines from 1971 to 1974 to cause such massive losses? Can an engine from 1974 be tweaked back to the point where it could have respectable numbers like those in 1971 with stock components?
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CID***** YEAR * CompRatio***** Horsepower**** Torque
318***** 1971 * 8.6 to 1 ********** 230 @ 4400 ** 320 @ 2000
318 **** 1972 * 8.6 to 1 ********** 150 @ 4000 ** 260 @ 1600
318***** 1973 * 8.6 to 1 ********** 150 @ 3600 ** 265 @ 2000
318***** 1974 * 8.6 to 1 ********** 150 @ 4000 ** 255 @ 2200
*

 

[67Dart273]

"Somewhere" around that time, the manufacturers went from alleged crank to "net" horsepower. But HP has always been a numbers game

Ignition timing, cam timing, they tried all kinds of stuff --except developing fuel injection, and so instead went the marvelous lean burn junk at some point, and Ma wasn't the only one, of course

In my old age, I can never remember if Ma played with cam timing "at the cam" or in the cam drive.

The "big" thing you can't just tweak out, in the case of the formerly known as HP engines like the 340, is getting compression ratio back, and of course nowadays, decent gasoline.

 

[C130 Chief]

Major difference between 1971 and 1972 was change from "SAE Gross" to "SAE Net" HP ratings. SAE Net was to reflect an "as installed" engine meaning an air cleaner, fan belt, full exhaust system etc... This was in response to some of the absolute bullsh*t ratings in the 60's, driven by the insurance industry. A level playing field if you will.

Compression ratios and timing advance curves also took a dive, but that really didn't make much difference on the 318 or 225. The hard parts really didn't change much. A 1968-71 318 probably made 150 "Net HP" on a good day.

 

[MopaR&D]

lol nevermind beat me to it

 

[rumblefish360]

It's all true, 100 percent.

If you want to tweak a 318 to a "Like" one of the older ones, you need some compression with a head milling, a MP distributor would be a good item as well.
From there, you might as well get a cam & 4b. Set up.