Installed new carb, not shifting at all now.

[Zachary]

Greetings all,

This might sound like kind of a dumb problem, but I think I may have just gotten a bit hurried to get a new carb on the car that I pulled something important off. So I installed an Edelbrock carb on my 1972 472 engine and it is not shifting at all at this point. I checked all the vacuum lines and I replaced the vacuum control module as well but it will not kick out of first at all.

When installing the carb I did pull off the downshift switch (I am pretty sure that is what it was called) if I remember correctly. Would this be affecting me shifting out of first? This is the switch assembly located on the passenger side of the carb, correct? I did the work when I was a bit sleep deprived so honestly, not all of the details are coming back to me right now, aside from the fact that I really need to take more breaks when I am working on cars.

Thanks in advance for any help!

[Dave Shepherd]

Disconnect the kickdown switch and post back the results.

[Big Fins]

He never had it connected. The K/D switch is in the drivers side, just outboard of the throttle linkage.

Quit wasting your time with an Edelbrock, and put the proper carb back on the car if you ever want it to operate properly again. The engine set up, manifold, throttle and shift linkages were all set up for a Rochester.

Are you racing this car? Is the engine in a race car? No? Do it right then and save yourself a lot of unneeded headaches.   

Fins

[Roger H]

Check that the vacuume modulator   has full manifold vacuum not ported vacuume.   If it has no vacuume the tranny will "think" you have your foot into  it and shift out of first  at about 60 mph.

[TJ Hopland]

He said he checked the vacuum stuff.   If you unplug the kickdown switch (thing that came off the carb) it should be fine you just wont get the extra benefit of the kickdown.  Its the same thing as the cables on most trannys.   If you left the switch in the harness and the spring is shot it may be telling the transmission to downshift all the time.   You could also unplug the single wire from the transmission itself.   IF you do it with the key on (engine not running) you should be able to hear a click inside the trans if thats your problem.  I have had more than one case where part of the harnesses melted together and caused all sorts of weird issues.

[Dave Shepherd]

Chastise number two coming, you did as I did, Zachary stated the switch was not connected to the linkage, I assumed maybe as you did the connector was still on, who knows?

[Guidematic]

The kick down switch only activates when the throttle is fully depressed, and it should have no bearing on not shifting at all, unless the wiring is somehow cross circuited.

It was not said how the vacuum was connected, and what sort of vacuum was there. You need manifold vacuum to the modulator, or the trans will not shift untill higher speeds are reached, and it will also freewheel.



Mike

[Zachary]

The kick down switch only activates when the throttle is fully depressed, and it should have no bearing on not shifting at all, unless the wiring is somehow cross circuited.

It was not said how the vacuum was connected, and what sort of vacuum was there. You need manifold vacuum to the modulator, or the trans will not shift untill higher speeds are reached, and it will also freewheel.

Mike

I did have it hooked up to the manifold vacuum, specifically the line coming off the back of the manifold right above the oil sensor. I just cannot figure out why I shifted just fine beforehand and now everything is haywire. I mean, it could be a coincidence, but most likely not. I have done this swap with great results before, not sure what went wrong this time.

[Dave Leger CLC #19256]

Zachary - could you have a vacuum leak from mounting the new carb?  Maybe a gasket mismatch that's blocking a port?  Did you put a vacuum guage on and see if the manifold vacuum level looks ok?

Dave

[John Abend]

Same thing happened to my '69 Coupe.  I replaced the carb with a remanfactured one, forgot to reconnect the kick down switch and it wouldn't upshift.  Once I hooked it back up, all was good, except for the fact I wore out my 1st and second gear on the tranny by forcing it to manually upshift before I realized my mistake.

John

["Cadillac Kid" Greg Surfas 15364]

My question would be "why did you go to a smaller, Edlebrock carburetor?".  Since they don't make on specifically for Cadillac the throttle arm does not have the proper attachment points for the transmission switch, and it is smaller. 750 CFM vs. the 825 CFM for a Cadillac Quadrajet.
If it was for performance, a performance rebuild by any of the several specialty shops would have given you everything you would need in the way of improvement and still have all the Cadillac specific features.
Greg

[Roger H]

Hello Again
Is it a turbo 400 trans? (two bumps on oil pan)
If it won't shift ,  forget about the engine for a bit,  here is what I would  do if it were  a customers car and I  did not know the history,  all I knew is it won't shift,  check the basics

1  check the fluid level, running, park hot
2  check the shifter,  when you move the handle does the shift valve in the trans move?
3  check vacuume AT THE TRANS,  ( small rubber hose at tranny not broken or came off ?)
4, test drive, if modulator related it should shift eventually at high rpm and speed
5  If still nothing,  pull the oil  pan and look inside for anything broken

Good 
Luck


Roger

[Glen]

Hi Zachary,

If I read this correctly the detent switch has been removed from the carb.  The question now is where is the detent switch and what position is it in?  If the switch is anything like the one on my 68 ELDO it has no spring to bring it back to the “at rest” position so it could be in any position including wide open throttle.

If it is in the wide open throttle position or if the wires have been shorted together then the detent solenoid in the tranny is activated.  That sets the shift points to very high speed. 

Once the detent switch (or its associated wires) are checked then you can start the other more invasive procedures.  I like to go for the easy stuff first. 

Good luck
Glen