Help Please!!
Background-
Installed a Vortec 350 and 4l60e out of a 99 suburban and into a 78' Shorty Van (similar to the A-Team van, lol).
Problem-
I cannot get the speed on the speedometer accurate and the shifting is all over the place! It will not let me choose tire size? It DOES let me change gear ratio which for some reason defaults a different tires size each time per ratio selected.
I have the option to enter the tire size and gear ratio, but it doesn't allow the "COMMIT" button to highlight to do this?
This is HPTuners by the way. I've changed and corrected speedos by GPS for years on various F-bods, Vettes, Lifted GMs and Lowered GMs on 26" wheels, lol. Never did any Vortec age speedo changing though and I guess I'm baffled.
Appreciate any help yall can throw my way.





