So my '90 Formula started life as a LO3 TBI 305 auto 2.73 gear. It has evolved into a L31 TPI 350 auto with 3.23 posi. I have modified the governor to get my WOT shifts up to ~4900 rpm and installed a "Corvette" servo. Shifts are pretty good, although the 1-2 shift at light throttle is probably a bit sudden. Car now has 21,xxx miles on it and the transmission has never been serviced, as far as I know. Fluid is nice red, doesn't smell burned. I know this transmission/converter is set up for a mild 305 and 2.73 gears, so I assume there's lots of room for improvement. My initial thoughts are higher stall converter and a complete fluid change. But at 32 years old, should I go ahead and do more while the transmission is out for converter swap? My other concern is traction. I already have limited traction; would a higher stall converter just make this worse?

 

Fluid and a Filter Change most always is good to do.

When changing Torque-Converters...
The new TC will often result in softer feeling Shifts, of the TC feels relatively looser than the previous TC.

I will almost always run the math on increasing the size of Separator-Plate Holes that affect Shift-Feel.
This will bring back the Shift firmness felt prior to the TC change.

Too firm is never good for the Hard-Parts of the Transmission.
Fast and Firm... NOT Harsh.

There are endless aftermarket parts offered for the THM700-R4 and 4L60E Transmission Family.
Much of which is never needed (you would be surprised what few aftermarket Parts are needed for most builds).
Part of the reason that so many aftermarket Parts get used...
Is because Customers love to see long lists of upgrades, and feel like they got what they paid for.

Depending on the Vehicle and Engine specifications...
Other Parts or changes to the Transmission could be recommended.

 

Thanks, good info. I've spent many hours over the last several months educating myself, but still don't feel confident enough to make any kind of decision.

 

I run a built 700R4 w/ shift kit and S10 TC and its perfect for a mild SBC. Gives around 2300 stall. It was for like a 96 S10 4.3Liter. $150ish

 

Update: Installed Dana's enhanced shift kit and Edge converter. As I feared, the new converter (~2,200 stall) doesn't allow for anything close to full throttle launch, though it does provide a nice kick when you punch it while cruising. Also,1-2 shift is now more normal under light throttle.