modulator vacuum line.
 

Sorry I messed up the last post.
My trucks line from the modulator is going to the back of the carb. Could this be the reason y it doesn't shift right. I've seen that the line should go to the intake, could I tap my edelbrock intake and put some connector in there. The engine and tranny are a 454/400 that came out of a 89 tbi r3500.
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Re: modulator vacuum line.
 

Mine is tapped off of the intake and I have never had a problem. Shifts fine, you should be okay.

Re: modulator vacuum line.
 

factory they come off the intake, I got one right now off the back of an edelbrock carb and it works fine.

Re: modulator vacuum line.
 

should there be vacuum at that port at all times? when i disconnect the line at the carb i dont feel any vacuum.

Re: modulator vacuum line.
 

You might have it hooked to ported vacuum. What carb do you have? usually the one at the back is full vacuum. I have always had better luck with hooking the modulator line to the intake and then hook your other accesories to the carb. I don't think you should need to tap the intake though, there should be a hole already there and its probably plugged with a bolt. Another reason it may not shift is the kickdown linkage may not be adjusted right.

Re: modulator vacuum line.
 

there should be vac. at all times, it's manifold vac. so it's all times. if there is none you need to change it, although ported creates vac. right off idle so it should work too but I always use full manifold vac.

If you have the fitting or plug and can remove it use the intake fitting it should be on the PS behind the cab, in front of the dist. My problem was they are always messed up and won't come out or afraid to crack it or something so I just t-'d mine off the back of the carb and used th eother side of the t for power brakes, never had a problem with it.

Re: modulator vacuum line.
 

i didnt know what the plugged port on my intake was, so i guess ill buy a fitting and get the vacuum from there. Since csb mentioned the kicked down i looked for it and found out the truck doesnt have anything. no linkage or switch.

Re: modulator vacuum line.
 

yeah its a 400. if you swapped it in your truck then you need to add the switch under your gas pedal i think for the kickdown.

heres the switch:

http://www.americanclassic.com/Googl...70NOS-1973.htm

it mounts to the accelerator pedal mounting bracket, you can find them in the junkyards sometimes. you can pull the wiring there, but it is only one wire and just needs 12v, pretty simple.

b7m also make a kit that adapts to the throttle linkage, pretty nice if your willing to spend $50 for it because you can adjust it to kickdown before you hit WOT :)

Re: modulator vacuum line.
 

cool, i'm gonna hit the junkyard after work and see if i find one, i could look for a window switch connector while im there since i need one too