How to check throttle linkage is adjusted correctly?

nero6 · Aug 15, 2010

Hi, I just purchased a 67 Coupe with a 289, automatic. I have always had fuel injected cars and just sold my 87 fox body Mustang so carburetors are completly new to me, trying to stumble my way through it. The car runs great, but seems to lack alot of power. At wide open throttle the car seems pretty lazy, I realize that a base 289 engine with an automatic is not going to great performance , but seems realy slow. I purchased the factory service manual and it says the gas pedal should be 4.5 inches away from the floorpan, my is about 3.5 inches. What is the easiest way to check to make sure the carburetor is opening completly at wide open throttle?

68stang351 · Aug 15, 2010

Remove the air cleaner lid, hold the throttle open on the side of the carb as far as it will go and look down the carb to see if the throttle blades are opened all the way.

nero6 · Aug 15, 2010

Thanks for the reply. What about the choke? I assume I have to get the car up to operating temperatur first so the choke will open completly, or can you just push open the choke?

Az Pete · Aug 15, 2010

You can hold the choke open. One thing.....you should have someone push the pedal to the floor and hold it, then look down the carb. I have found at times, the pedal will stop its travel and you can still open the throttle more by hand under the hood.

2+2GT · Aug 15, 2010

Az Pete said:
You can hold the choke open. One thing.....you should have someone push the pedal to the floor and hold it, then look down the carb. I have found at times, the pedal will stop its travel and you can still open the throttle more by hand under the hood.

While you friend is holding the pedal down, check the thottle lever on the carb. If it is not fully opened, adjust the throttle rod until it is. Also, check the kickdown to see that it is fully pulled at this WOT (wide open throttle) position.

nero6 · Aug 16, 2010

I had a chance to follow your advice. I assume the throttle blades are suppose to open up almost perpendicular to the carb throttle body when they are wide open? Right now they barely open up at all, about 20% if I had to guess. I adjusted the rod as far as I could but ran out of thread on the rod. I checked it again and now they open up about half way. I assume the wrong rod was used as I can't adjust it anymore. Is there any place you would suggest to get the proper one?

2+2GT · Aug 16, 2010

nero6 said:
I had a chance to follow your advice. I assume the throttle blades are suppose to open up almost perpendicular to the carb throttle body when they are wide open? Right now they barely open up at all, about 20% if I had to guess. I adjusted the rod as far as I could but ran out of thread on the rod. I checked it again and now they open up about half way. I assume the wrong rod was used as I can't adjust it anymore. Is there any place you would suggest to get the proper one?

There only is one rod, nothing else even comes close. Most likely, the firewall is distorted where the linkage attaches. A small amount of re-bending will give you more than enough to get back in the game.

Az Pete · Aug 16, 2010

On one of my '66s, I had very little movement in my throttle pedal, allowing a small opening of the plates. After much checking, I decided to pull the gas pedal up while the linkage was held in place by a friend. You do not want to put that kind of pressure on the carb linkage itself. I pulled it up about 3/4" from where it was and allowed me full throttle when re-adjusted. Out of 4 '66 Coupes, I only had to do this with one. I believe it was caused by poor engine installing by a PO.

How to check throttle linkage is adjusted correctly?

nero6

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Az Pete

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