Re: 66 Powerglide slipping
Jed,again,its the same problem as was stated earlier,it slips more between low and high gear with more gas due to more load on the trans at that time.
Its a very common issue with the glides,my father had a car lot in the 50s-early 80s and 7 or 10 glides did it and would last over 100k doing it too.
But a good shop that knows glides should fix be able to tweak it to get rid of the sloppy low to high shift .
For now untill you get it fixed use a normal to considerable mount of gas when getting going from a stop but then about when you would like it to shift back off the gas approx 1"-1.5" to remove a little power to let it shift . Doing that helps it to ont slip & slide as much when shifting from low tohi gears ,then righ after it shifts into hi gear simply reapply that 1" -1.5" of gas you had backed off untill your up to your desired cruise speed.
But no matter what the problem is (adjustment/modualtor-etc) take it back to the builder,thats the right way to get it corrected so he doesnt blame anyone else for messing it up if there are any issues down the road with the trans leaving you holding the bag.
1969 CHEVELLE SS396,ORIGINAL #'S MATCH,GOT IN 1978,(In 2001 rblt/bored original 396 .030 to 402)/M20/12BOLT/3:31'S
2002 MAXIMA (DAILY DRIVER/1 owner,GOT 3/2013 w-44k miles)
2009 HD ELECTRAGLIDE CLASSIC ULTRA (GOT 11/14 W-9,700 miles)