I have an 82 fbird that im trying to make a super gas saver "opec give us oil or else "
Well any way i have 305 "carb", 2:72 gears and a craptacular turbo 250 in it.
I have two 700r4 trans that came out of cars with 3:73 gears and im itching to use one.
Would it be overkill to use a 700r4 with 2:72
gears maybe get 10000000 miles per gallon
If anyone has used this combo before or has an opinion about it please let me know?

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85 Camaro RS 350/350 stealth intake, holley street avenger 670
true dual exhaust. "ButtStang killer"
82 firebird 305 all original - the cat and smog crap."All show No go"

 

It's not overkill at all. That's exactly what my donor combo was. I think I'd be safe in saying that 100's of thousands of 3rd gens came w/305, TH700R4 & 2.73 gears.

I averaged about 18-19 mpg commuting and 26 on the road when I had those gears. Hasn't changed much with the current ratio.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/LB9 block, ZZ3 cam and intake, TBD heads, Hooker headers & y-pipe, 3" Catco cat).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" headers, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere. Daily driver while Camaro was being put together.

 

I have seen tons of 305 carbed bird and camerons with 2.73 gears and 700-r4 trans they are lucky if they get that good of gas mileage. some that have switched to 3.23-3.42 range actually get better milage. I guess it takes less hp to move the car and at the same time you are not cranken alot of rpms so you balance out.

 

A carbed engine usually runs most efficiently over 2,000 rpm due to fuel atomization. So yes 2.73's and a 700R4 could get worse gas mileage than a car with 3.23's since this gets it back into the proper RPM band for efficient operation. EFI doesn't care about engine speed that's why the new cars are pulling 1,600 RPM at 65.