New to this forum looking for a little help and advise. I have a 1987 Monte Carlo with a 427 big block and a th400 strapped to a 2500 stall, and a 8.5 grand national rear end, 4.10 posi rear end. Problem is the shifts are wwaaayyyy too soon at 5 mph I'm going to second gear. And at about 24 I'm going into third. It goes without saying that there isnt much more room to accelerate before I'm well above 4000 rpm. I changed the vacuum mod and was looking into recalibrating the governor just wanted to be sure it was the right decision to make. All advice is appreciated THANKS!!!!

 

most Vacuum modulator are adjustable.by removing the vacuum hose and inserting a straight blade screwdriver into the vacuum fitting. Turning the adjustment changes the preload on the spring, therefore altering the shift points.

 

Get the recalibration kit for the governor. Do you know what car the trans came out from? Grocery getter car trans shifts much earlier than the high-performance trans. If the trans came out from, say Cadillac, it will shift way too early for your need.

Vacuum modulator only adjust little, so my bet is on governor. You need to go under the car frequently to get the shift right. I've done this when I had my TH-350 w/3.73 gear on my SS. It's not fun, but once you get it right, it should be good!