It shifts too early into second,2nd to 3rd is fine. Adjusting the modulator and/or governor springs only raises or lowers BOTH shift points.
It's an '84 350C converted to regular 350 using pump, input, converter from a '79 th350 and a Superior Products HP 350 Shift correction package which came with a 2-3 shift valve spring. Should I put the original 2-3 spring back? The trans came out of a 1/2 ton pick up (if that matters).
Also, I have gaskets VB gaskets if it needs to come out.
Thanks for any advice.

 

If it is lighter than the one you have now. Otherwise you can try trimming the 2-3 spring OR trying to modify another spring for the 1-2 valve. I know you don't want to hear this now but both the TransGo SK and Reprogramming Kits come with shift springs and governor springs that are right on. They tend to put the sifts more on the early side (but have an option for later if you have low gears) which almost always makes the engine feel like brand new.

 

Heres what I have found out so far, The 2-3 spring in my trans should be red, reading the instructions of an old trans go shift kit they use a white 2-3 spring. I no longer have the springs out of that kit but I have the seperator plate with the oil transfer plate spot welded to it, I also have a complete trans with a trans go kit but it's sep plate has no oil transfer plate (never did). I am wondering if it would have the white spring.
The problem seems more like third is too late and is made earlier by the governor springs which in turn makes second too low.
Thanks for the ideas Leo, what trans go kit does it sound like I have in that spare trans? The separator plate says trans go on it. Must not be a high perf kit. What am I looking for to make third shift sooner? Stiffer or softer spring? Thanks again

 

The one W/O the transfer plate is the 350 Shift Kit. It will have the same shift timing springs so you should use it with the Reprogramming Kit plate. There is one solid coil bound spring that is different in the Repro kits that is optional IMO, it provides Man1 at any speed which isn't for everybody. Be sure to use the correct modulator or you will not have correct shift timing. The small can/red stripe one that everyone uses is for either non-EGR engines (different vacuum curve) or low gear cars. The larger can which many tranny shops won't even have, is the one most need.