Q: I have a 66 Impala. I end up changing the tranny out for a 350 turbo. The car runs but it won't pass 15 mph.

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I have a 1966 Impala with a rebuilt 350 turbo transmission.The car turn on but when I try to go out for a spin the car doesn't want to pass 15 mph. wondering if anybody might know the problem? Please let me know, thank you.

My car has 20 miles.
My car has an automatic transmission.

The symptom you are describing could arise from an engine or transmission related fault or even a combination of both. As far as the engine, you want to check ignition timing and advance function (distributor) as well as fuel pump pressure and supply. On the transmission, of course a question is was it re-built correctly? Issues there range from faulty clutch packs, leaking pistons, slipping bands, defective torque converter and so forth. The level of suspicion I would apply to the transmission depends on exactly who rebuilt it; if a professional, you might diagnose the engine first. In any event, a mechanic can distinguish between an engine related cause versus the transmission and so my suggestion is you request an engine diagnostic for slow acceleration and the responding certified mechanic will resolve it. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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