The rotational mass of a torque converter and flex plate/ring gear is greater than a flywheel, clutch plate, and disc? I suppose, if you have an aluminum flywheel.  

My last longer trip that I took with my 54 ( warmed over 312, 4 sp, 3.50 rear) I got 17 MPG.  This was a trip of over 900 miles, most highway but some city.  I generally don't compute MPG around local.

TBird was less, last big trip was 6300 miles, overall I got 14.  A lot of highway, 65 -70 MPH.  Stock 312. C-4, stock 3.31 rear.  Included a ride up Mt Hood in Oregon.


54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

Paul, isn't the Tbird a couple hundred pounds lighter? Were you driving with the top down?

I'm sure it is.  Really can't account for the difference.  But there was more stop and go on the longer trip as we stopped at a number of tourist places on the way out and back, including a stop for Hot August Nights in Reno on the way back

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54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

My 57 T Bird weighs 3,600 pounds. I’m thinking that the 54 would weigh a little less.  Best I got with it is 17 mpg on an economy run. Worse was 9 mpg around town with my foot in it. Was running factory E setup with 3.89 gear and 3 speed stick. 

Slumlord, how did you weigh your Tbird? I've not seen any specs that confirm 3600 lbs. Overdrive? 

A quick search for 57 Tbird weight shows a low of 2980 and a high of 3350. Does your 3600 include the driver's weight?

I've confirmed my mileage with GPS and its pretty close to accurate. The 3:72 rear was a factory option for police cars soo the gear should be close. I can't tell you about the engine settings. Ted did that on his dyno and I haven't changed it since. He may still have the info. I was quite pleasently surprised by the mileage but the AOD transmission throws a curve in the numbers too.

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

MoonShadow, the AOD OD ratio of .67 gives you a final drive ratio of 2.49 (not factoring in tire diameter). Although this is numerically lower than DLR's 2.74, your engine is far from stock. Based on posted numbers, I can only conclude that his mpg could/should be better. Did you retain the AOD lockup converter? Without lockup, a big cam could be a problem at low rpm highway cruising speeds. Apparently, in your case, the weight of the torque converter is not an issue as far as your mpg is concerned. However, this does make me wonder if DLR's torque converter could be slipping at lower rpm. 

I used a 2500 stall converter so no lockup. I certainly didn't expect that type of mileage until I had to drive the car home from the Y-block nationals. My tow van lost an engine so I left it and the trailer behind for repair. A pleasant surprise! The overdrive automatics do wonders for fuel mileage. I've asked a transmission company it I can swap in one of the 5 or 6 speeds with the AOD adapter. They say those will replace an AOD in a normal application. 

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

I’ve weighed its several times over the years at my local grain elevator and at the drag strip. The 57 Custom 300 I had in the late 60s was about 3600 pounds with a 390 and 3 speed. I’ve found that factory advertised weight is usually less than real world weights.