I recently bought a '77 corvette with original 350/350 3-speed automatic transmission. Ported and Polished, bored 30 i believe. Everything is in perfect working order right now but I am considering doing some county touring and want to see if I can be more economical. I am thinking of a 4speed with overdrive but would love a stick shift. I have a mechanic on hand but wanted to get everyone's opinions on exactly which would be the best move for me. I will keep the original numbers matching transmission in case i ever want to put it back on but what I"m looking for now is a cruiser, not a racer..... I would appreciate any feedback, questions, or suggestions and thank you all for your time.....
If you want to add more gears there are a few tried a d true options. For an auto, the 700R and 200R get you from 3 to 4 speeds (although one of them requires more "fitting" than the other). For a stick the TKO 500 and 600 are clear front runners. All these have been done in enough numbers that there are kits where all thie issures have been addressed (or are at least known). There are other swaps out there but these are the most common.
BTW, in order to get the most out of your swap you need to know your rear gear ratio and be prepared to possibly change it. /:\
I've put in the 700R and love it. That said if I had to do it again I'd probably do the 200-4R.
The 700R4 is marginally stronger than the 200-4R. I had the 700R-4 rebuilt and probably would have had the 200-4R rebuilt had I gone with it. Both are quite capable once strengthened. So its a wash as far as which is stronger.
I had my driveshaft shortened with the 700R. I had vibration issues and had to remove and rebalance 3Xs. (She's good to go now though).
The 200-R4 is exactly the same length as your TH350 and your old driveshaft will bolt right back on.
1st and 2nd gear are different ratios on the 700R vs the 200-4. IMO if you have a steeper gear like a 3:55 (I do and you probably do to) you'd be happier with the 200-4. My transmission shifts pretty fast out of 1st and into 2nd. If on the other hand you have more of a highway gear like a 3.08 (like the '82 vette that came with a factory 700R) you'd probably like the 700R.
So the only downside I have with mine is the quick shift from 1st to 2nd. Both come with the lockup converter.
Another bonus going to the 700R or the 200-4R is that 1st gear is 30% lower than your TH350. Your 3:55 gears would act like 4:62 gears. You're getting some pretty cool stump pulling torque and a 30% OD!
After all is said and done - I will say that of all the mods I've done the OD transmission is #1. I used to hate going out on the highway. Now I look for any excuse to get out there. Everyone I've ever talked to has said the same thing. It's right up there for putting a smile on your face everytime you get in your car.
Last edited by couperdecar; 05-19-2011 at 06:44 AM.
Once you put a true OD trans in your car youll never go back to a 3 spd auto or 4 spd stick again. You can gear the car low to pull hard on the street and still cruise at 80 with reasonable revs even with a big cam. Best of both worlds.
You didn't mention your rear axle, but if staying auto, would go 700R4, as commonly availible, and lower 3.05 1st than the 350. A friend put a Kiesler TKO 5 speed into his 79' L-82 w/3.73 axle, and quite happy with the improved highway cruising rpm's. Pretty sure 1st's lower on that one too, but cost's some buck's.