Most fuel efficient drivetrain for an A roadster build?

Thanks for that. I will add that to memory. Gracias Hombre!

 

Okay, now things aren't so hazy!

 

Recently completed two customer rides. '49 Buick and '49 Chevrolet. I used Jasper 350 pre '77 blocks with Edelbrock air gaps and 600cfm carbs bolted to Jasper 4L60E tranmissions. One has a 12 bot the other a 10 bolt. Ratios are 3.08 and 3.23. Both get between 22 and 24 mpg and if you put your foot in it, that close ratio automatic doe's the trick. We install a toggle switch under the dash to engage the OD. The Jasper 3 year /100,000 mile warranty isn't bad either. Got a '28 Ford roadster that I've had since '58. Has a 350/2x4 and 400 turbo, 2.70 gear, best 20 mpg. My '26 has a 13 to1 377/auto/9" 4.56 spool, get's shitty fuel mileage more like a TANK ie gph, but it is the most fun to drive!!!! Damn thing would burn up 4 gallons of the expensive
stuff making one pass from one end of Paso to the other end. RIP Rich

 

pm me for the cummins info

 

My old '60 Pontiac would pull 18 highway from a 4000 lb car, in an A I would think you could pull 22-25 out of it. 389, 2bbl, dual-coupling (4-speed) Hydro, 3.08 rear. Fun to drive, too. What's a Model A weigh with a V8 and with you in it, 3400 lbs tops? Makes a smaller hole in the air, too. I'd say don't be afraid of a big motor and a highway gear, as long as it has plenty of low-end torque you should be able to do more than reasonable in the milage department.

 

My wife had a Chevette Diesel when we met, they used an Izuzu motor and it would get over 50MPG outside of California,the diesel fuel there would drop off about 8 MPG.She gave it to Her daughter at 134K and she traded it off at 220K only thing ever changed were brakes and a water pump.

 

If money is no object, try a 283 or 327 with RV Cam, Vortec Heads, EFI and Magnacharger, then a 6-speed auto and 3.08 gears.