When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I have a 460 with a rebuilt C-6 behind it, it has extra clutches for 1st and drive, shift kit and all the other basic rebuild stuff.
The problem is no matter how fast you are going if you floor it, it is going into 2nd gear whether you like it or not. This wouldn't be bad if it was at normal 2nd gear speeds but I am talking about 75+mph, and that leaves my 460 screaming over 6000 rpm.
I've adjusted the linkage so that it only pushes the kickdown at WOT, but this left normal driving shifting way to early, and it still goes into second at a 75.
Right now I have resorted to leaving the linkage of and just manually shifting it, I know it won't hurt it but it knida defeats the purpose of having an automatic.
You might try leaving the kickdown off and adjusting your shift points at the vacuum modulator. Pull the hose off, and you will see a screwdriver slot. Screwing-in should raise the RPM at which it shifts during take-off.