[1975yellowC3]

I have a TH350 in a 75 corvette. The car had the lackluster L48 motor when I bought with some minor mods. The car had not detent cable when I bought it. When in drive, the car would shift into passing gear pretty consistently.

I have since stroked the motor and some other upgrades. Since I put the engine back in, the tranny will not downshift to passing gear. I did install a 2500 stall. That is the only difference than before.

It also shifts into 2nd and 3rd pretty quickly. It doesn't let the engine get into the power band enough.

I have read several posts on here that say you won't get downshifts if you don't have the detent cable, but I didn't have it before and it would downshift to some degree.

Any help is appreciated. I know zero about transmissions!

[Crosley]

in some situations the vacuum modulator will make the trans down shift if the detent cable is un hooked.

Sounds like you need a detent cable now or manual shift the trans at the RPM desired

[SSedan64]

If your Stroker engine has a Cam with longer Duration, it probably has less/lower vacuum signal going to the Trans Modulator.