Below are pictures showing the details of the Rambler 327 V8 engine block, as well as a comparison in size and design of the AMC (Gen II) and Rambler (Gen I) V8 engines. You will note the physically larger size of the Rambler V8. The Rambler 327 V8 engine block weighs about 30 lb. more than the 155 lb. AMC 304 V8 engine block shown. While most people desire a "lighter" engine, this extra 30 lbs. is due to thick wall casting.
Here is a comparison of the Rambler 250-287-327 3.25" stroke (left) and AMC 390 3.574" stroke (right) crankshafts. BOTH are forged factory units made from 1035 steel. Both have a 2.249" rod journal, while the Rambler crank has a 2.50" main journal and the AMC 390 crank has a 2.75" main journal diameter. The Rambler crank is physically longer (due to rear main design) and has larger radii counter weights, they're also slightly thinner than the AMC 390 weights. Another noticeable difference is the rod journal width for the Rambler engine. The Rambler rod is 1.00" wide, while the AMC 390 rod is 0.92" wide. The Rambler rods are forged steel, as are 390 V8 rods, but they're 6.375" long center-to-center. These longer forged Rambler rods would be a good candidate for use in a 390/401 AMC V8, if the crank's rod journals were widened.
