Transmission problems

Hello! I just acquired a 1974 Mustang II (2.8L V6). It had not been driven in 3 years and seemed to be in good shape. I know nothing about carborated vehicles and need some help. The motor runs perfect (in my opinion). The problem I am having is the transmission is not shifting properly. I was told that the shifts are controlled by manifold vacuum. I have random vacuum nipples with no vacuum lines and I am LOST! The vehicle shifts late about 800 - 900 rpm's after I feel that it should. It also seems like the last person working on the vehicle had no idea what they were doing. I can post a picture if it would make your life easier. I just need to find out what lines control the transmission. Thanks in advance for your help.

First check the fluid. Is it topped off? Is it discolored or does it smell weird, burnt?

It's fine....I had them do a flush and fill just the other day.

I'm not familir with 2's at all but you need to find out if the Vaccuum regulator nipples are suck or blow. And then you can basically hook almost any matching type vaccuum port to it. Also all the remaning vaccuum ports on the car should be blocked off.

I can check by starting the car and putting my finger on the nipple to find out if it sucks or blows, right? Then I am guessing that I connect one that sucks to one that blows...? (this conversation is starting to sound weird :lol: ).

Bump

I don't know about your transmission/engine, but for mine(c6/351c), I just ran a vacuum line straight from the intake manifold to the vacuum attachment on the transmission. On c6s and c4s this is at the back passenger side of the trans on the bottom. The c6 I had was stock, and it would shift at like 3800 at WOT. So whenever I was racing, I'd disconnect the vacuum hose and it would shift at around 4500. I have since blown up that c6 so I replaced it with a reverse manual shifting c4, so no longer any need for the vacuum line. And if you have any unused and unplugged vacuum nipples on your manifold, PLUG THEM OFF! its not good for fuel metering and performance, and if you have any vacuum accessories(vacuum secondaries on the carb, power brakes, vacuum advance distributor...) its not good for those either.

All of the extra vacuum lines have been plugged. So you ran it straight from the vacuum tree on the intake manifold to the lines for the transmission? I have 2 lines going to the transmission...are they both vacuum??? By the way it is a c4.

You have 2 lines coming from your trans? You sure one isnt a cable for your shifter or an oil line for a trans cooler? There should only be one vacuum line going to your trans. If you can, get under your car and find out where all these lines go... that would help to figure out what you've got and where they go.

There are definately 2 lines. I had it up on the lift yesterday to replace the transmission vacuum modulator. There are 2 nipples on the modulator and 2 lines comming off the tranny. This is all hooked up from a 4 line plastic "thingie" bolted to the firewall. Looks like a vacuum tree. There are two sides to the "thingie" (ex. The 2 on the right don't seem to be connected to the 2 on the left). We have it hooked up like this....far left nipple receives manifold vacuum, 2nd from the left goes down to the tranny. 3rd from the left receives port vacuum and the one on the far right goes down to the tranny.