I must respectfully disagree regarding Jim Burek. PAE is no more, and their approach to variable pitch converter modifications were flawed. That was then, this is now: http://www.v8buick.com/showthread.php?t=196600 http://www.v8buick.com/showthread.php?t=181479 http://www.v8buick.com/showpost.php?p=1323960 Devon
Interesting to know. The dealings I had with Jim a few years ago seemed very up front. I guess that explains why I couldn't find a website for him.
the engine will remain the same just going to run a dual 4 barrel rather than the stock single 4 barrel.
Got it. Next question, sorry if it's not necessary. Are you familiar with "stall speed" as it relates to torque converters? I should have asked that up front. Devon
No problem, I thould have thought of providing info first. I hope you don't mind some reading, it will really help: http://en.wikipedia.org/wiki/Torque_converter "Stall speed" with most automatic transmissions is fixed. At a stop, foot on the brake, the engine idles fine. As you apply throttle, the engine's rpms rise a bit and off you go. The "stall" is the engine RPM at which the torque converter gets the car going, for lack of a better description. In '65; GM released the "variable pitch" design for the ST400. They released a torque converter that could switch from a lower stall speed to a higher one when demanded. This was a big help for heavier cars. With the variable pitch function, applying 2/3 throttle would give you a higher "stall" rpm, which would give the heavy car an easy advantage for acceleration by allowing the engine to reach a higher rpm as you hit the throttle, but for cruising low stall was most efficient. For what you're doing I think the variable pitch is is a blast. We have to figure out the best way for you to handle the wiring for the way you like to drive the truck.
Alrighty... On the left side of the trans case there's a small male double-prong spade electrical connector. When the bottom vertical spade sees +12v, you get the detent energized for passing gear. When the top horizontal spade sees +12v, the torque converter switches from low to high stall. The factory did this with electrical switching on the throttle linkage, here's a diagram: http://home.comcast.net/~shinzan/ST400_linkage.jpg It's a great setup, which is why Ed wanted you to get the parts from a donor car if it's possible. The plunger switch next to the carb shown in View C does two things; at approximately 2/3 throttle it energizes the top terminal on the trans for high stall during acceleration. At 3/4 throttle it also energizes the bottom terminal for passing gear. The switch on the throttle linkage in View B energizes the top terminal for high stall whenever the throttle is closed which minimizes the tendency for the car to creep forward at a stoplight, and can help improve idle quality. You may or may not need that last feature depending on how the truck behaves. If you don't want to run the factory setup, there are other options... For more fun, I don't rely on the original plunger switch to manage high and low stall, instead I use a momentary switch on my gearshift. It sends +12v to the top terminal so I get high stall whenever I hit the switch. For the detent, you might be able to adapt the later TH400 switch used by GM which attaches to the throttle linkage just above the gas pedal for passing gear when you need it. If you find your truck likes to see high stall at a stoplight to help idle quality and prevent forward creep, you can energize the top terminal on the trans with +12v from the brake light switch, so you'll have high stall whenever your foot is on the brake pedal. Some folks are using electronic timers so that high stall is energized for a preset time before automatically switching to low stall, usually tuned to coincide with the car hitting the 60' mark at the dragstrip. Those are some options, some folks run a combination of them depending on how they like to drive. Hope that helps a bit. Devon
So the wiring for this is not an easy install. Would I need to have an actual transmission guy install this or is it something I can do in my drive way. I have minimmal mechanic knowledge
I'd have whomever is going to install your transmission handle it depending on what you want to do. Devon
Wicked 50 stated that his engine is a '61. Is he going to have problems with the pilot hole in the back of the crankshaft being too small for the TH-400/SP-400 convertor? Thanks, Ken
Various threads state that adaptor kits are available, answering his earlier question. http://www.v8buick.com/showthread.php?p=1601905 Devon
Your also going to need the later starter, as it has a different snout length. I personally like Devon's method of using high stall, and is what I plan on doing. Devon, I'm assuming you don't use the passing gear detent since you run a manual VB? Just curious...
Cool, thanks. Not to hijack, but I have another question for you. With your manual VB, do you still need to have vacuum modulator hooked up?
Nope, no more modulator. The plug in the side of the case keeps the modulator valve fully inserted into the valve body. Governor is welded in its "at rest" position. I should add it isn't an aftermarket valve body, just a stock one with modifications to disable automatic function. Devon
Ok, thanks. I think I'm going to be running the same "manual VB", the Trans Go reprogramming kit that disables all automatic functions.
ALL TH400's, or as Buick refers to them as ST400's, had electronic kick downs. There are tons of aftermarket "TH400 kickdown switches" available at places like JEGS and Summit. It would be really easy to convert one of these to work with your switch pitch. If you were okay with the s/p and the kickdown working simultaneously, you could wire both to the same switch.
