Classic Mustangs (Tech)Technical discussions about the Mustangs of yester-year.
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I have just purchased arestored 1970 MACH 1, 351 Cleveland with a FMX transmission and aEdelbrock 4v carb.
I have noticed that it does not downshift when put to the floor. Car will sit up from the extra gas but does not drop down a gear.
I found on-line that the Edelbrock Carb. does not connect to the downshift linkage properly and purchased a downshift extension from Edelbrock. The part is nothing more than a 2 inch piece of metal with a few holes in it. The Edelbrock part number is 8011.
The part came with no instructions so I am not sure how to install it.
The FORD Shop manual indicates to "hold the throttle shaft lever in wide open position and adjust the downshift screw to 0.05-0.07 clearance".
I assume that means the downshift linkage is pushed as far as it will go, TOWARD the transmission, when the adjustment screw is set.
It seems to make sence that when the carb. in wide open the tab on the carb. makes contact with the downshift linkage to drop down to the next gear.
Anyone ever have this problem?
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That sounds pretty right. What I did ( while I flooded my carb ) Push the throttleback towards the rear of the car and adjust the screw so that when you stomp the gas (or not) it pulls the throttle back far enough to smack the kickdown screw and shift the car. It may take you a few tries to get it to where you like it.. On my FMX I had the screw just about all the way in, so that it really didnt take me "stomping" on the gas to get it to the passing gear.
I welcome you to the FMX club,, I have one with my 351W and really liked it after I adjusted the vaccum modulator so that it would stay in second gear longer than a 2 seconds.. Not many of the guys on this forum have an FMX,, mostly C-4's and C-6.. It sounds like you got it right though..
69 Grande' 351W/AOD Performer Intake/Cam, 670 Holley Avenger, Hooker Headers, 3.70 9"TracLoc
67 Fastback A Code: 64k Miles, all original project for the wife.
I worked on the adjustment and it seems to work fine now. I'll give a HOW TO just encase someone else needs to know.
First I removed the spring to the kickdown linkage and usinga hook made out of a piece of coathanger and a piece of string I tiedthe throttle wide open.
I added the Edelbrock extension to the kickdown linkage. While holding the kickdown all the way down Iadjusted the screw to spec. of the tabon the throttle.
I removed the string and let the throttle return to the normal position, replaced the spring,and tried the kickdown to make sure everything moved smoothly.
OOPS....the kickdown linkage did not return from the downshift position. I thought the problem was the newextension binding and might need some lubrication. NO, not the problem. The problem was the lower end of the kickdown linkage was rubbing on the exhaust pipe just enough to keep it from returning. I added more tention to the spring and went for a road test.
With the FMX in drive and cruisng at 25 mph I hit the acceleratorand....... WIPLASH.
The indestrutible FMX. Thats what mine has. But its days are numbered. I'm converting to AOD. The 37 year old FMX has never been serviced except for routine fluid and filter changes. Unfortunately the shifter shaft has oblonged out the hole through the tranny wall and even a new seal can't stop it from leaking. The FMX is dead, long live the FMX!
2006 Red Fire GT Convertible.
1970 Medium Lime Metallic Mach 1
1997 Pacific green/silver F 150 ext cab 4x4
2002 Navy Blue Escape 4x4
2009 Smokestone Mercury Milan Premier
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