looking for information on 1971 383 Magnum

[jamesvoodoo]

Hello,

I was hoping somebody could help with what made a motor a Magnum or Commando? In some references the "standard" 383/440 have the same horse power rating

Looking for the information in general and specifically for 1971. I am thinking about restoring a charger that originally had a 383 Magnum.

What does the cam look like, what type/size of carb
Are the 440 and 383 intake manifolds the same? Are the heads?

thank you

james

 

[69Coronetrt]

By 71, the Magnum was in name only and used on the 4bbl version of the 383 as opposed to the 2bbl version. From 68-70 there was a separate 335 horse assembly that was different from the standard 383-4bbl 330 horse engine.

 

[jamesvoodoo]

That is good to know

Was the addition hp from higher compression (we know that dropped waaaay off in 71) or warmer cam? Did that different assembly come from using 440 heads? (or is that rumor)

 

[69Coronetrt]

That is good to know

Was the addition hp from higher compression (we know that dropped waaaay off in 71) or warmer cam? Did that different assembly come from using 440 heads? (or is that rumor)

For the 68-70 B body 335HP:

Heads were always the same. Calling them "440 heads" was a marketing thing I guess.
More aggressive cam profile, valve springs were different.
Windage tray.
Different carb (typically. there were lots of variations over the three years)
Unsilenced air canister.

Here's a comparison on the '68s. 69 and 70 comparisons are similar.

 

[jamesvoodoo]

Another member sent me some information to sure
The 1970 and 1971 versions of the 383 were the same for the following
Same Holley Carb
Came int:268 exh:284 with a 46 degree overlap

The difference was in the compression, 9.5 down to 8.5 to 1 which accounted for the drop of 35 horses

based on the information shared earlier, there appears to be a horse power increase (5 hp) with a difference air cleaner (wow). Unsilenced and dual snorkel

So much to read through and learn And the 383 is interesting since there are two versions of the motor

good times

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