Transmission problems

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Jul 10, 2013 | 12:42 PM

1973F100Kid

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Transmission problems

Hey yall i was hoping if someone can help me out. I went threw 2 trannys on my 73 f100. And whats strange is that both had the same problem. It goes into R and D fine but when i take off it wont shift gears. And there both c6's. I have a 351w in it that i put in from a 90 crown victoria. I converted it to a carb set up. Can i get some help ill really appreciate it. Its my first truck and i dont want to let her go....

Jul 10, 2013 | 01:01 PM

mikeo0o0o0

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From: Stanley, VA

Is the vacuum line to the modulator hooked up and is it in good shape? Not kinked or cracked.
The vacuum line is the one that goes from the modulator to the rear of the intake manifold.

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Jul 10, 2013 | 03:11 PM

1973F100Kid

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Im not sure i wil have to check. You think that can be the problem? Like possibly?

Jul 10, 2013 | 04:53 PM

mikeo0o0o0

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From: Stanley, VA

If the vacuum line isn't connected to the modulator, or the modulator is bad, the transmission thinks you have the throttle floored.
Have you tried shifting it manually?

Jul 10, 2013 | 07:01 PM

1973F100Kid

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Yeah checked it out a while ago but i didnt see anything connected behind the intake nor the tranny and yeah i tried shifting manually but it doesnt do anything.

Jul 10, 2013 | 07:31 PM

mikeo0o0o0

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From: Stanley, VA

Connect a line from the intake manifold down to the modulator. On a C6 it's on the rear, passenger side just above the pan, next to the tailshaft.

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Jul 10, 2013 | 10:06 PM

1973F100Kid

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Ok i will have to check it out tomorrow. Please keep in touch lol. Its the 2nd tranny i go threw with the same problem. Also the passing gear is not connected you think that has to do with that problem to?