al714

hello,

Well my problem was that my car started to shift hard after i installed a newly rebuilt quadrajet from 1st to 2nd it almost feels like it takes a long time to shift. i checked to see if i installed all the hoses and they are installed.I know its not the carb cause the car is actually running more powerful except for the shifting. Any things that i should check? i did checked the transmission oil and its on full. I have a 1972 cutlass supreme 350 everything stock

oldcutlass

How does it shift from 2nd to first? Do you think you swapped the vacuum line to the modulator with the one to the distributor?

Lady72nRob71

Modulator vac line hooked up? Any cracks int he line?

oldspackrat

Sure does sound like the vac. modulator. Check hose routing again & also check the short hose at the transmission itself. Sometimes those crack or break.

al714

Oldscutlass: when it goes from 2nd from first it acts normal.Im sure i didnt cross the hoses because theres only two outlets from the carb one to the valve cover and another going to the distributor and that one is plugged while i get my new advance canister. Lady72:The line looks ok it comes out of the intake towards the back of the engine. Oldspack : Dont want to sound dumb but where exactly is this vac modulator and what should i check for?

oldspackrat

On turbo 350 transmissions, the modulator is on the right rear of the transmission, just above the pan. It should have a short piece of rubber hose that is connected to a steel tube that runs up to the passenger side of the engine, and then another short piece of hose that connects to the intake. On turbo 400 transmissions, the modulator is on the right front of the transmission just above the pan. There is a small rubber diaphragm inside this modulator and if it goes bad you may have this problem but you would also lose transmission fluid.

al714

Would a bad adjusted carb do anything to effect the transmission?

oldcutlass

Anything is possible on the carb, but probably not. When you find the modulator, the small rubber line connects to a steel tube thats routed back up to either the manifold or the carb. You should have manifold vacuum to the modulator. Also remove the line connected to the modulator and see if there is any fluid leaking from the port on the modulator. If yes then replace, its a simple repair.

Next question are your shift points really high 1-2 and 2-3?

al714

I'll check that today.. When it shifts from 1-2 it does seem high when it shifts .. Like engine is going to blow.. Well not to that extreme

oldcutlass

Sounds like your modulator is leaking, if not, there may be an adjustment screw inside that accepts a small slotted screwdriver. You might just turn it CCW 1-2 turns.

al714

Ok so I checked the the modulator and it was ok no leak or anything but when I checked the rubber hose that connects to it and the metal tube and was hard as a rock. Problably hasn't been changed since 72... Soon as I changed it and drove the car.. Wow the car has never shifted this smooth since I had it. Thank you everybody for the help.. Especially oldcutlass for the detailed instructions

oldcutlass

Good deal glad it worked out.

Axeni

I love these forums.