WOT, mine shifts at a weak 4700. Gonna have to work on it. I want it to shift fully auto at about 5700, that way I can keep the original column shifter for that stock look.
Mine shifts at 5300 during WOT and the 1800 sounds about right also during normal driving. It is a drastic contrast with the OD trannys we are used to in modern rides but does not mean we cant go retro and be happy. My 3.25 rear is about the most gear I would want for a DD but for a spirited weekend car the 3.55's would be my first choice in my combo. .373's are great but the cruise rpm's may get on your nerves.
Turn your modulator in CW a couple turns to adjust the shift point higher if needed.
you can't manually shift your C4? The shifter should say D-2-1, start out in 1 go up to whatever rpm you please, bump the shifter to second and it should shift shortly afterwards, then repeat when you get ready to hit 3rd (D). Every C4 I've ever had has worked like this, even in stock form. Only when in D do the pre-set shift points come into play.
I thought you guys were poking fun at us C4 guys until I read 66's sig. Sorry for the confusion. I can actually shift my c4 manually too believe it or not.