833 trans swap

[aaronk785]

I have a 68 dart with a 340 9.8 to 1 comp. ported 2.02 j heads 237 242 at .050 cam rpm intake and 750 dp. I am now running a 904 and 2400 vert and 3.55s. Thinking about a 833 overdrive and 4.10 gears. Do you think I will lose 1/4 mile performance or gain. Car runs 12.90s now.

 

[Marcohotrod]

now u have a 3 speed, what size rear tire? with more rear gear and running the a833 overdrive in the first 3 gears at the 1/4 she will be quicker. been there

 

[aaronk785]

Thanks Marco. Cheapest way of getting overdrive I can find. Tires are 26 tall.

 

[j par]

It will be harder, but a lot more fun. Likely not as consistent, but a lot more fun. More work, but a lot more fun.
My car is for fun, guess what I have.....

 

[SBM4theW!n]

I don't have much experience with a 904, but I have an 833OD and 3.23s.
The 4.10s might help, but with 3.23s the split between 1st and 2nd is pretty brutal. Between this and the aluminum case of the OD unit I'm starting to look for a older 833 nonOD trans. That said, I haven't had any issues with mine behind a 10:1 360. But I don't run slicks.

 

[j par]

Okay if I read it correctly this time you are looking for quarter mile performance? My bad I always look at things the way I like them the fun factor! Sorry.
Quarter-mile performance is going to be best with that 904 transmission. It's going to shift faster and and be lighter. It may suck up more horsepower to run it but the benefits on the other end for someone trying to go and get quarter mile performance is worth it. Remember I'm a 4-speed guy and love them and race with one, but I'm recommended automatic for what you're talking about. And if you have four tens go ahead and use those with the automatic. That might just improve your time right there? Just don't plan on doing a lot of freeway driving LOL but you still can. I was just wondering is this your full intention of just making the car quicker in the quarter mile or do you like driving this thing around town?

I don't have much experience with a 904, but I have an 833OD and 3.23s.
The 4.10s might help, but with 3.23s the split between 1st and 2nd is pretty brutal. Between this and the aluminum case of the OD unit I'm starting to look for a older 833 nonOD trans. That said, I haven't had any issues with mine behind a 10:1 360. But I don't run slicks.