Help needed: vacuum lines

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78_Monte970

Apprentice
Jun 2, 2019
58
20
8
Colorado
I have a 350 swap in my 78 with a th350. It currently doesn’t go into gear. Yesterday I found a line under the car that had fallen off from the vacuum modulator, and it seems it was hooked up to the egr port on the Edelbrock 600 carb. Does it need full manifold vacuum? Is that a source of full manifold vacuum? Do I need to put in a nipple on the manifold and run it to there? Is there anything else that can prevent it from going into gear?
 
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bracketchev1221

Royal Smart Person
Jan 18, 2018
1,386
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It is usually full manifold vacuum on that line, but I think that would really only cause it to not shift right once moving. It should not impact moving forward and back.
 
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pontiacgp

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Mar 31, 2006
29,270
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Kitchener, Ontario
the vacuum modulator tells the transmission when you are in cruise by way of vacuum and allows the trans to shift out of the lower gears earlier. Like bracketchev1221 said it won't stop the transmission from going in gear. Did you check fluid color and level in the transmission?
 

78_Monte970

Apprentice
Jun 2, 2019
58
20
8
Colorado
the vacuum modulator tells the transmission when you are in cruise by way of vacuum and allows the trans to shift out of the lower gears earlier. Like bracketchev1221 said it won't stop the transmission from going in gear. Did you check fluid color and level in the transmission?
The car has been parked since I don’t know when, I checked it and it seems okay but I thought you needed it to warm up and go through the gears to get a good reading. The linkage moves, the transmission just doesn’t engage.
 

pontiacgp

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Mar 31, 2006
29,270
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Kitchener, Ontario
you do need to warm it up and check it in neutral to get an accurate reading but checking it cold gives you an idea if you have enough for the transmission to work. Maybe one of the guys in here can give you an idea if a solenoid or something else could be stuck with it sitting for a long time
 

78_Monte970

Apprentice
Jun 2, 2019
58
20
8
Colorado
the vacuum modulator tells the transmission when you are in cruise by way of vacuum and allows the trans to shift out of the lower gears earlier. Like bracketchev1221 said it won't stop the transmission from going in gear. Did you check fluid color and level in the transmission?
Hey thanks for the help man, turns out all it needed was a couple quarts. When I checked it it said it was full but then again it’s been sitting since at least June. Feels good to have
you do need to warm it up and check it in neutral to get an accurate reading but checking it cold gives you an idea if you have enough for the transmission to work. Maybe one of the guys in here can give you an idea if a solenoid or something else could be stuck with it sitting for a long time
hey I was actually typing a reply as you posted it, turns out it just needed a couple quarts. Feels good to have it run, thanks man
 

pontiacgp

blank
Mar 31, 2006
29,270
20,391
113
Kitchener, Ontario
Hey thanks for the help man, turns out all it needed was a couple quarts. When I checked it it said it was full but then again it’s been sitting since at least June. Feels good to have

hey I was actually typing a reply as you posted it, turns out it just needed a couple quarts. Feels good to have it run, thanks man

that was easy enough, always look at the basics first....glad you have it moving
 

MrSony

Geezer
Nov 15, 2014
6,792
6,677
113
Des Moines, Iowa
Good. Keep checking the fluid level as you drive it.
 
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