I have an 401 nailhead in a 32 ford with buick trans ...It doesnt like to shift ..until its warm and even then ....? any help/advise ???
No really sure its a 400 sp st ? its shifts sometimes when you let off gas ...my thoughts were vacum issue ?
If it has a modulator, check for full engine vacuum when idling. Also some modulators are adjustable and may have been tampered with. Any history on the trans? Could also be a governor sticking. In order to upshift> governor pressure must override throttle pressure (modulator)
If it is a Buick Dynaflow transmission, they don't shift when in drive. I think 1963 was the last year for the Dynaflow. Yours may be operating properly.