3-Speed Turbo Hydra-Matic 400 vs Powerglide

Q: 3-Speed Turbo Hydra-Matic 400 vs Powerglide

Does anyone know if I put a turbo 400 tranny in my 1967 firebird if it would have a lower end than my powerglide. How much? Is it worth it. I have 326 H.O. in the car. Any help is appreciated.

A: You’ll have to change out your transmission cross member for a 400 unit (available from resto parts catalogs). A cheaper solution would be to go with a short tailshaft Turbo 350. It would be plenty strong enough for a 326 and will use the existing cross-member. The gear ratios of the transmissions are as follows:

Power Glide 1st-1.76; 2nd-1.0
Turbo 350 1st-2.52; 2nd-1.52, 3rd-1.0
Turbo 400 1st-2.48; 2nd-1.48, 3rd-1.0

As you can see, the real benefit is in the extra gear for acceleration (lower first gear plus the added second gear). Because, the final gear ratio is 1.0 you’ll get no benefit at the top end. You’ll have to decide if it’s worth it. Me, personally, I’d go with a 2004R and gain overdrive.

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