Machine Manifold

0069X wrote: Can anybody tell me "exactly" what the difference is between a Rebel Machine's intake manifold, and a "Non-Rebel Machine" 1970, 390 manifold? Photos would help, but not required. Thanks

I don't know that I can tell you everything, but I have 1 of each. From what I can see, the Machine manifold has a center divider , instead of 4 individual holes. It looks more like an Edelbrock Performer opening, except for a slot which connects the primary sides. This makes a much larger, more open plenum area. Also, down in the manifold, the passages are smoothly radiused or rounded below the mounting pad, instead of having sharp edges. That is all that I can see. They look the same from the top and side, other than the carb mounting opening.

Thanks Alex, it makes sence to me, that those few minor differences could easily add up to a 15 H.P. increase over the "standard" 390 manifold.
The reason I asked, is because I've noticed during the last few years several articles in magazines (and the internet) where some owners have inaccurately listed their "stock" 70-390 AMX's as having 340 H.P.
I assume they figure that the 325 H.P. rating only covers 390's in non-Ram Air configurations, and since the Rebel Machine has a Ram Air, and is rated at 340 H.P., then Ram Air equipped AMX's (and Javelins) must have 340 H.P. as well.
As we all know, the only AMC's with a "Factory" 340 H;P. rating was the Machine, and the AMX3. (Well, laughinly) the SS/AMX as well.
It just drives me nuts when ever I see AMC misinformation in print, because once it's in a Magazine, or on the Internet, it's gospel.

to Sonic Silver...

Charles Smiley wrote: to Sonic Silver...   As I recall, the Machine intake was taller too. More than a machine shop could help with. Anyone have them side by side to know for sure?

I believe that they are the same height.

Charles Smiley wrote: I read a car magazine from 1970 (It may have been Car Craft) that tested AMC, Ford, Chevy and Mopar engines with displacements around 390-CID. They wanted to see if any of the HP claims were honest. The only one that was even close was the AMC 390 rated at 340-HP. Anyone recall that article?    I had a Hornet 360 4-spd that I swapped the intake and card from a wrecking-yard Rebel Machine and it made a serious 'seat of the pants' difference -- with no other changes. Eventually though I switched to a Torker intake to save some fron end weight for 'canyon racing'.

What intake and carb did your Hornet have before you swapped out? I assume that it was a 71 SC/360 with the factory 4 hole intake and Autolite carb. Correct?