Automatic transmission not changing gears!

[jhut]

I'm helping a friend with his truck. It's a 1970 F100. 240. Single barrel Ford carb. Automatic transmission. We just took it out of storage. I drove it about 10 miles and everything was fine. It had a small crack in the manifold so we took it off and replaced it. I don't know if we screwed up the linkage or what, but now it won't change gears. I drove it down the road and had to shift into 2nd manually. Maybe the vacuum hose running to the transmission isn't connected to the right spot? I really have no idea what I'm doing here. Any advice would be appreciated.

[Donnie]

jhut, make sure that the kickdown linkage is returning, that is the rod that runs from the carb to the trans. & be sure that you have the line from the manifold to the trans connected at the MANIFOLD to FULL VACUUM & it is still connected at the trans....DONNIE

[jhut]

Thanks Donnie. The line going to the transmission is connected to an adapter that's screwed into the manifold. It has two ports. I think the other one is running to the distributor. Does that sound right?

[colnago]

Sounds right, if it's connected directly to the manifold. You can probably hook it to the carb, but you have to know which port(s) are appropriate. You might have a vacuum leak that's large enough to cause problems (mine has a steel line from the tranny, and a steel line to the manifold, but a 6" rubber line connecting these two), or a clogged line going to the tranny. I agree with Donnie about checking the kick-down lever. In the winter, mine won't shift into 3rd until it heats up enough, but this late in the season, that's not going to be your problem. Any pics?

Joseph

[jhut]

Here are a few pictures. The white hose is connected to the metal line running to the transmission.



Here's a shot of the linkage. I think it's all working correctly.

[Donnie]

Where does the other line coming off this brass fitting go? Make sure that you do not have a vacuum leak somewhere else.
Does your engine run smooth at idle..? Check your engine vacuum at the manifold & at the trans..they should read the same..........Donnie

[colnago]

Hmmm, I assume that rubber line on the brass fitting goes to your distributor, but that means it's getting manifold vacuum at idle, not ported vacuum. Do you have any other vacuum ports on the carb itself?

What's the linkage doing down at the tranny? You should have the shift linkage going from your shift lever to the tranny, then a second linkage going from the carb to a separate tranny "kick-down" linkage. This gets engaged when you romp on the gas to pass, and causes the tranny to downshift. Like Donnie mentioned, is this returning when you let off the gas? Your second photo shows so many rods, I'm not sure where any of them go!

Looks like your brake booster line is lying across some sort of moveable linkage. What is that? You probably want to re-route the booster line above that hard linkage connecting the throttle linkage to the firewall. That way it can't get in anybody's way.

By the way, I assume it's a C-6 tranny, but I'm not sure what would be behind a 240 in a 1970 truck.

Joseph

[jhut]

Quick update! There was a crack in the vacuum line running to the transmission. We replaced that and it's working great now. Thanks for the help