As a rule, as the compression ratio goes up, so does damper weight.  With the belt actually riding on the damper, then there is some dampening taking place in the belt itself but would be somewhat variable depending upon the tension on the belt and the drag from the accessories.  Both styles of dampers are interchangable with each other in that the belt pulleys are in the same location on each.  Given the option, I’d prefer the damper ring being located behind the pulley in lieu of the pulley being the damper ring.  There’s enough timing mark issues with the dampers without having an accessory drive belt constantly trying to slip the damper ring and the timing marks even quicker.

Lorena, Texas (South of Waco)

That is good to know Ted, thanks.  What about the weight difference, damping effectiveness of one vs. the other, or crossover applications?

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.

The damper in the upper right would appear to be the damper from the early 60’s Y engine.  The belt pulley on that one is mounted on rubber similar to the Fe’s of the same period and this design is prone to an earlier failure due to belt tension also working against the rubber.

Lorena, Texas (South of Waco)

Chuck, I dont think so, but am not sure.  Long ago I pulled a motor from a 1960 Ford car, but also took some parts from a 256 F-600.  This had to come from that era of parts searching. 

The upper unit is truly a damper with rubber seal around hub and outer ring.  It may look like the pulley is unweighted, but it is.  The weight is approx. half the thickness of the heavier unit, but larger in diameter than the heavier truck model.  To look at the two together you would think the truck model was much more in weight than the COA(E), more than 1.5 lbs.  If there was supposed to be an E in the parts number, it was done away with due to a factory hole in the area. 

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.

Isn't the upper dampner from a 239 or 256? Chuck

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

Below is a pic of two dampers.  The one at the low left position is from a 62-64 pickup.  The other is the subject of the questions.   It has marking COA 6316A.  1960 auto?  The COA is 6 1/4 lbs, the truck unit is 7 3/4 lbs.  Can they be considered interchangeable?  Would either work in a 312? 

Of the 10 or more dampers I have had, only this one (COA...) has shown up.

Mike

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.