Go Back   Ford Mustang Forums > Mustang > Classic Mustang > Classic Tech

Welcome to our Mustang forums where Mustangers come together to hang out, discuss and enjoy their favorite Mustang hobby with fellow Mustang enthusiasts. We invite everyone to read, post, and enjoy our Mustang forum as well as the many other sections of our site.

You are currently viewing our forums as a guest. By joining our community you gain access to post topics, communicate with members, upload your photos and access many other special features. Registration is fast, simple and free so why wait, join our Mustang community today! If you have any problems with registration or your account login, please contact support.

Classic Mustangs Tech Forum

Technical discussions specific to 1964-1967, 1968-1970, and 1971-1973 Classic Mustang. Discuss all tech related to in-line six cylinder and V8 powered Vintage Mustangs here.

Classic Forums | Classic Talk | Classic Tech | Classic Pictures | Introductions | Mustang Tech | Mustang Lounge 


Reply   Post New Thread
Unread 09-03-2012   #1 (permalink)
Pugdaddy is offline Rookie


Joined: Sep 2012
Posts: 22 Threads: 9
 Pugdaddy's Country Flag
Trinity   North Carolina
Pugdaddy is on a distinguished road
Default 1966 GT Modulator Vacuum Line

Hello All, Been reading the forum for a while and this is my first post...Love the forum..One of the best forums I read and participate in...Thank you!

just got my 66 GT coupe back from paint shop..Also has rebuilt 289 (boy she sounds great)...They forgot to hook up modulator vaccum line... I have a non original manifold and think the original line went to the carburetor...(No taps in the manifold)..I have the Holley 4160 carb...

So, question then, is where does the line hook up on the carb...I know which is the spark advance...The vaccumn line on the back of the carb is hooked to the hole in the valve cover. On the right side of the vehicle is another port at rear of carb. I{ hooked the modulator vaccum line to this one and it still doesn't change gears. On the lower front passenger side is a small port. And two ports about mid way on carb. The top is plugged off and lower one is open...(Saw one phote oin internet where there is line hooked between these two...

Reason for asking all this is car won't change gears abviously...

Thanks all for allowing me on the forum and for advice as well...have a great Labor Day..
Attached Thumbnails
1966 GT Modulator Vacuum Line-66gt-carb-ports.jpg  
Pugdaddy is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Sponsored Links
Advertisement
 
Unread 09-03-2012   #2 (permalink)
Joes72/65 is offline GT Member


Joined: Jun 2009
Posts: 1,462 Threads: 33
 Joes72/65's Country Flag
Imperial Beach   California
Joes72/65 is on a distinguished road
Default

The modulator line should hook to the manifold, not the carb. I have never seen a manifold that did not have a vacuum port somewhere, so it might be capped off. What kind of manifold is it? If you have a brake booster, you can use a T-fitting to tap into manifold vacuum where the booster line connects to the manifold.

Bear in mind that I am not familiar with Holleys (I stick with Ford carburetors), and am not sure what that myriad of ports is for. I am only sure of the way Ford intended for it to work. If there is a way that Holley intended to run the modulator off the carburetor, I am ignorant of it and have never seen it, but that doesn't mean it can't be.
__________________
Joe
'65 Coupe, 302, Autolite 4100, C4, 2.80
'72 Grande, 351C, Motorcraft 2100, FMX, 2.75
Joes72/65 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Unread 09-03-2012   #3 (permalink)
Pugdaddy is offline Rookie


Joined: Sep 2012
Posts: 22 Threads: 9
 Pugdaddy's Country Flag
Trinity   North Carolina
Pugdaddy is on a distinguished road
Default

I have the Edelbrock 289 Stroker Intake....Just looked again with a mirror....The vacuum line going from the valve cover is hooked to the back of the intake below the carb....Isn't that supposed to be hooked to the carb directly and not the intake....If that is the case that would free up the port on the intake for the modulator vacuum line....I think....Can someone conirm maybe? Thank you!
Pugdaddy is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Unread 09-03-2012   #4 (permalink)
Joes72/65 is offline GT Member


Joined: Jun 2009
Posts: 1,462 Threads: 33
 Joes72/65's Country Flag
Imperial Beach   California
Joes72/65 is on a distinguished road
Default

Confirmed. Running PCV to an intake runner is bad juju. Since there is airflow through it while the engine is running, it leans out whatever cylinder it's going to. There is no actual airflow through the modulator line, though, only a vacuum signal.

In short, you are absolutely correct.

You may have to adjust your idle mixture slightly richer once you have it hooked up correctly, since there will be slightly less venturi vacuum pulling fuel through the idle circuit. (Unless that's just an Autolite/Motorcraft thing!)
__________________
Joe
'65 Coupe, 302, Autolite 4100, C4, 2.80
'72 Grande, 351C, Motorcraft 2100, FMX, 2.75
Joes72/65 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Unread 09-03-2012   #5 (permalink)
Jeff P is offline Rookie


Joined: Aug 2012
Posts: 15 Threads: 0
 Jeff P's Country Flag  View Jeff P's HomePage
Peoria   Arizona
Jeff P is on a distinguished road
Default

There are two "types" of vacuum. Manifold and ported. Manifold vacuum comes from the piston going down in the cylinder with an intake valve open. Ported vacuum is simply from the air moving down the throat of the carburetor.
You want to connect the modulator tube to manifold vacuum. This can sometimes be found on the carb also. Find a rubber cap and see if it has a lot of suction at an idle. If so that is manifold vacuum.
__________________
Current Projects...
66 Mustang Coupe
69 Mach 1
69 Mach 1 (yes there are two)
67 Cougar 8 of them!
67 Ranchero
70 Ranchero
Always looking for a 66/67 Fairlane 2dr.
Jeff P is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Unread 09-03-2012   #6 (permalink)
Pugdaddy is offline Rookie


Joined: Sep 2012
Posts: 22 Threads: 9
 Pugdaddy's Country Flag
Trinity   North Carolina
Pugdaddy is on a distinguished road
Default

Well, I changed the line from the modulator to run off the intake....Car still won't change gears? What should I try next?
Thank you!
Pugdaddy is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Unread 09-03-2012   #7 (permalink)
Joes72/65 is offline GT Member


Joined: Jun 2009
Posts: 1,462 Threads: 33
 Joes72/65's Country Flag
Imperial Beach   California
Joes72/65 is on a distinguished road
Default

I would use a hand vacuum pump to check the modulator and line for leaks and blockages. Start with the simple (and best of all, easy & cheap!) things first.
__________________
Joe
'65 Coupe, 302, Autolite 4100, C4, 2.80
'72 Grande, 351C, Motorcraft 2100, FMX, 2.75
Joes72/65 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Unread 09-04-2012   #8 (permalink)
daveboss200 is offline Apprentice

Classic Member


Joined: Aug 2012
Posts: 248 Threads: 9
 daveboss200's Country Flag
Huntsville   Texas
daveboss200 is on a distinguished road
Default

u may need a new modulator valve if the vaccuum signal is good and there are no blockages or leaks in the vacuum line. Just a question before you do that, what was done to the tranny while the motor was out? was it in good shape before?

One last thing, make sure the fluid level is correct if you changed the converter or if you emptied the old one.

The modulator valve can also be adjusted through the vacuum nipple to increase or decrease the shift point.

hope you get this resolved quickly.
daveboss200 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Unread 09-04-2012   #9 (permalink)
Pugdaddy is offline Rookie


Joined: Sep 2012
Posts: 22 Threads: 9
 Pugdaddy's Country Flag
Trinity   North Carolina
Pugdaddy is on a distinguished road
Default

I had the tranny overhauled before the engine was done...like 4 years before and quit working on the car....Tranny has maybe 5 miles on it....I doubt the modulator was changed....I am going to try vacuum test, then try adjusting the modulator, then....if that doens't work keeping asking question on the forum...Will post an update.....Thanks again!
Pugdaddy is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Unread 09-05-2012   #10 (permalink)
daveboss200 is offline Apprentice

Classic Member


Joined: Aug 2012
Posts: 248 Threads: 9
 daveboss200's Country Flag
Huntsville   Texas
daveboss200 is on a distinguished road
Default

if it has been sitting for 4 years, u may have rust on the bands and they are stuck to the planetary gear housings, or valves that are stuck preventing proper fluid movement for shifting. run a transmission conditioner product like lucas. or transx or trick shift fluid to help loosen things up. u might have to loosen up the bands to free them and then readjust.
daveboss200 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Sponsored Links
Advertisement
 
Reply   Post New Thread



Thread Tools



Mustang Photos
Mustang Links    Top Sites    RSS    Link To Us    Add to Favorites    Archive    Terms of Use    Site Rules    Privacy    Contact    Sponsors    Advertise   
AllFordMustangs is not affiliated with or endorsed by Ford Motor Company. ©Copyright 2002-2011 All Auto Enthusiasts Network

Search Engine Friendly URLs by vBSEO 3.5.2

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172