Yeah, I was really posting for those who don't know about all the poly motors. Lotta confusion about fifties Chrysler Corp motors.
When I replaced my timing chain, I found out that 56 Plymouth poly motors had a one year only cast iron timing cover, with the water pump sitting higher than later motors. The 57 Plymouths were lower, with a lower hood line, lower radiator, etc. so the 57 poly water pumps sat lower to put the fan in the right place. The 56 water pumps are also unique to that year.
Going by memory, the 277s were 56 and 57 only, 301's were 57 only. After that, except for the 59 Dodge 326 with its .040 over bored 318 and hydraulic lifters, all American Plymouth poly motors were solid lifter 318's. Interestingly, Chysler Corp. stayed with solid lifters for the new 273 LA motors. So when you hear someone say, yeah, the Commando 273 had a hot solid lifter cam, you can say, yeah, the two barrel motors also had solid lifter cams that were only a little milder than the hi-po 273s.
Finally, the 61 and earlier 318 poly motors used an extended crank that the torque converter bolts to directly, without a flex plate. The back of the blocks are also different. You'd need some kind of adapter to hook one up to an aluminum Torqueflite. 62 and later, not a problem.
Here's a pic of the front of my 277 when I was putting it back together after installing the timing chain. Did a little cleaning/painting while I was at it. My 277 did not originally have a vibration damper; I put one in from a 65 318 poly, along with the fan and crank pulleys, and the 318 poly timing tab (also used on 273's). Fan is a NOS 56 Plymouth fan. Notice the gap between the damper and the timing tab. The tab closely hugs the damper on the LA motors, mine is probably an inch away.
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