Stock Piston/Rod Specs Materials/Weights

["R L Rapp" <masheen@xxxxxxx>]

>From Page 4 of the 1970 model year AMA Engineering Data/Specifications for
AMC 304, 360 & 390 engines:
      Material: Aluminum Alloy with Steel Insert
      Description and finish:  "Autothermic", Flat-Top with Valve Pockets,
Slipper Skirt, Tin Plate, Steel-Strut Inserts.
      Weight (piston only) oz.:  304/17.92      360/21.27      390/21.94
      Clearance (limits):  Skirt:  304 & 390/.001-.0018 (2)
360/.0012-.002 (2)
                      (2)  Clearance measured at 2.31" below top of block at
centerline of piston pin.

An interesting factoid I found on page 5 of the specs about connecting rod
material:
      304 & 360, Cast Nodular Iron (1)
      390: SAE 1042 Mod., Forged Steel
                      (1)  Special Service Rods for 304 & 360; SAE 4340
Forged Steel (Dealer Kit).

      Weight (oz.):  304 & 360/24.16       390/28.15

I don't know what the "Mod." reference in the spec on the 390 SAE 1042 rod
means, but I'm pretty certain that the rod material (SAE 4340) used in the
dealer kit (and noted as special service rods for the 304 & 360) is
stronger.


Bob Rapp
NN, VA
70 Machine