Author Topic: Throttle Return Spring Problem '69 351W  (Read 6897 times)

Offline drummingrocks

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Throttle Return Spring Problem '69 351W
« on: October 11, 2013, 10:41:14 AM »
Hi guys, I've been fighting a problem off and on since I got my '69 Mach 1 back together.  I've had lots of '65-66s, and to me, the gas pedal on the '69 has never felt right.  It's always felt like the cable is binding slightly, and recently, the throttle started hanging slightly open above idle.  It was annoying but not especially alarming, as you could kick the pedal slightly and it would back the accelerator linkage back down to idle.

Since this is the first '69 I've had, I've not had much experience with the cable-driven throttle setup.  I'm using a new reproduction throttle cable from NPD.  So far, I've:
1. Taken the cable back out and oiled it until oil ran out of both ends
2. Verified that the cable is seating properly both at the gas pedal and in the bracket on the back of the carburetor
3. Tried a concours AMK reproduction throttle return spring, as well as a variety of other generic parts store springs

I'm running a newer Edelbrock 1403 (500cfm) 4-barrel carburetor along with the original throttle cable bracket.  The only modifications I've done are as follows: When it became apparent that the throttle cable linkage wasn't going to be travelling straight, I made a bracket that moved the factory throttle cable/return spring bracket towards the driver's side of the car in order to give the linkage a perfectly straight path of travel.

As far as I can tell, this setup should work, and should work well.  The cable runs perfectly parallel to the carburetor linkage, and it doesn't appear to be binding at all.  However, the pedal is still stiff throughout its entire motion of travel, and it feels like there's way more resistance than there should be, along with the aforementioned problem of the pedal hanging slightly above idle.  When I install a stiffer return spring, it eliminates the problem of sticking above idle but makes you want to drive with two feet on the pedal!!

I know this is something that would be much easier to troubleshoot in person, but I was wondering if someone else might have any ideas or had run into a similar situation before.  I absolutely don't know where to go from here, and the car is staying parked lately because I can't stand driving it.
Too much junk, too little time.

Offline drummingrocks

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Re: Throttle Return Spring Problem '69 351W
« Reply #1 on: October 11, 2013, 10:51:11 AM »
Could someone post a picture of the factory throttle cable setup on a '69?  My car is a '69 Mach 1, 351W, FMX, built in June at Metuchen.
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Offline krelboyne

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Re: Throttle Return Spring Problem '69 351W
« Reply #2 on: October 11, 2013, 11:53:44 AM »
Bet it would work fine with the correct Autolite 4300.

It is not uncommon to have throttle linkage and transmission kick down rod problems, when installing after market carburetors and or intake manifolds. The factory 1969 throttle cable has a specific length. Ford designed the intakes and carburetors to accept one cable length for their V8 engines. Edelbrock carburetors are basically redesigned  Carter carburetors.

The fuel line inlets are way around to the far corner of the Edelbrocks.
Scott Behncke - Carcheaologist
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Re: Throttle Return Spring Problem '69 351W
« Reply #3 on: October 11, 2013, 05:20:53 PM »
Brent, My 69 Mach1 Metuchen built is a 2 bbl, 351W,FMX. Would that help?

Offline Brian Conway

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Re: Throttle Return Spring Problem '69 351W
« Reply #4 on: October 11, 2013, 07:00:59 PM »
     Got the same catch in my throttle cable.  428 motor, after market intake and carb.  My OE cable, woven steel cable jacket, did not stick but was unraveling at the gas pedal side of the firewall.  Replaced it with the, hard plastic jacket, NPD one and noticed the two step acceleration right away.  The NPD reproduction is a very nice piece but I think the inner cable binds on the hard plastic right where it comes through the fire wall.  My intake and carb set up makes the accel. cable loop rather than a straight shot from the carb to the firewall.  As Krelboyne pointed out you mess with the OE set up and you pay the price.  Brian
« Last Edit: October 11, 2013, 10:13:39 PM by Brian Conway »
5RO9A GT  4 Spd Built 5/29/65
9TO2R SCJ 4 Spd Built 9/19/68
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Offline drummingrocks

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Re: Throttle Return Spring Problem '69 351W
« Reply #5 on: October 12, 2013, 09:43:25 AM »
Brent, My 69 Mach1 Metuchen built is a 2 bbl, 351W,FMX. Would that help?

Hey Richie, for some reason I thought all along your car was a 4-bbl car.  I wouldn't mind taking a look at the setup on your car.

Thanks!
Brett
Too much junk, too little time.

Offline rockhouse66

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Re: Throttle Return Spring Problem '69 351W
« Reply #6 on: October 12, 2013, 01:00:14 PM »
Is the little plastic sleeve still intact on your cable?  If not, and it is floating around, it might catch on the outer sheath and hang up the throttle.  You can see the small diamter inner sheath in this picture:

Jim
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Re: Throttle Return Spring Problem '69 351W
« Reply #7 on: October 12, 2013, 09:46:06 PM »
Hey Richie, for some reason I thought all along your car was a 4-bbl car.  I wouldn't mind taking a look at the setup on your car.

Thanks!
Brett
It's a factory H code 2bbl 351W. It's even got the original carburetor and set-up.

I will get some photos tomorrow and post them 8)

Offline J_Speegle

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Re: Throttle Return Spring Problem '69 351W
« Reply #8 on: October 13, 2013, 02:22:25 AM »
69 4V application - sorry engine was on a stand so no throttle cable attached but pretty easy to figure that one out ;)

Jeff Speegle

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Re: Throttle Return Spring Problem '69 351W
« Reply #9 on: October 13, 2013, 11:13:24 AM »
Brent, here's a few photos of the carb and throttle cable w/spring. I had to replace the throttle cable in 2004 due to a carburetor fire while driving to Nashville for the 40th Mustang celebration. Everything else you see is original.....Hope this helps.

Oh yea, you'll see a clear manual oil pressure line because I put manual Shelby oil pressure and water temperature gages where the ash tray was because we drive it and I like the manual readings of the engine. (The ash tray was not butchered during the installation).

Offline app01

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Re: Throttle Return Spring Problem '69 351W
« Reply #10 on: October 15, 2013, 03:20:42 PM »
From my 69 Mach 1 351W 2v  FMX. Metuchen May 69 build. Not sure if it is 100% correct however.

Tony

« Last Edit: October 15, 2013, 03:25:08 PM by app01 »
Currently own:
1970 Boss 302 - Yellow- May 1970, Dearborn
1970 Mach 1 -Sept 1969, Metuchen
1962 Corvette 340hp

Previously Owned:
1967 Mustang Convertible (My 1st car)
1970 Mach 1 (my 2nd car)
1989 GT
1969 Mach 1 (<29k miles, Unrestored, MCA Gold)-sold in 2012

MCA #62598

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Offline drummingrocks

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Re: Throttle Return Spring Problem '69 351W
« Reply #11 on: October 16, 2013, 12:17:55 PM »
Thanks, everyone, for all of the pictures and advice.  I haven't had a chance to work on the car since I last posted this.  I'm wondering if I don't have a defective cable?  Maybe there's a burr inside the plastic sheathing that I can't see?
Too much junk, too little time.