1967 Ford LTD- Strange engine acceleration

[Patrick1967]

Hello, I have a:

1967 Ford LTD V8.

When I start the engine to let it warm up, after 30 seconds or so, the engine begins to accelerate on its on, while in park. To test, I put car in drive and began going down the street. The car was accelerating on its own, even with my foot not on the gas pedal. I have to press the brake pedal to the floor to get the car to decelerate. I even had to slam the car into park at 5 mph or so, because I could not get it to completely stop. I have daily turned the car on, and after 30 seconds or so, the car begins to accelerate, even while car is into park. Has anyone had any experience with engine acceleration, while in park, with no pressing of gas pedal? Thanks everyone, Patrick

[Oldtech]

You need to check the basics like the throttle linkage and choke, but I suspect you have a vacuum leak, likely the power brake circuit by what you are describing.  If the choke remained on fast idle you might have this problem, but the fact that the brake doesn't seem to stop it make me think there's a problem there. What happens when you just start the engine and let it run. Does it speed up more than it should?

[TerryB]

Regular carburetor or add on throttle body fuel injection?  

[joe_padavano]

How about a more basic question - what non-stock items are on the car besides the obvious ones we can see in the photo?

[58 Speedster]

I had the same problem and it was a broken motor mount on the drivers side.

[JACK M]

Does it have a cruise control?

Motor mount is not uncommon.

[keiser31]

Yep....look at the motor mounts.

[TerryB]

That GM recall to put a small length of chain from the engine to the frame comes to mind.

[intimeold]

Well, Let's Not assume that this car is still using the Ford carburetor.

 

See the Edelbrock air cleaner and aluminum valve covers. What is under that aftermarket carburetor?  Edelbrock makes really good equipment and done so for decades. 

 

This is my professional opinion.

 

1. The dry and dirty condition under the hood of that car; could be a factor. The carburetor/ choke linkage may need cleaned and lubed. Doesn't matter, what carb is used there.

 

2. I am going to rule out a broken motor mount; even though these cars at that time had that problem. I had worked on this problem and actually experienced it in a customer's car. When you accelerate the car, the engine can twist, to the right violently, if you are going forward.  The throttle on these cars would be forced Full-Throttle; until the engine went back down. This is violent; he doesn't seem to have that urgency. Maybe a little; but he would be really freaking out.  If he was able to avoid hitting something.  

 

3. If after checking the motor mounts; I would proceed to the choke and fast idle linkage; if the motor mounts were good. That car, with the original Autolite carburetor, has a multi step fast idle cam; which is controlled by the position of the choke plate.  If the choke is not opening up ( not heating ) the linkage will stay on one of the fast idle cam steps. The choke and fast idle work together, to enrichen the mixture, when the engine temperature is  not up to a specific temperature.  I am saying all of this, not knowing if the Autolite carb is still there.  But if it has been changed to a Holley or Edelbrock or something else; there is something similar that works about that same way.

 

4. It doesn't look like anybody has been under that air cleaner; by the amount of road grime on everything. I would like to see what is under the air cleaner. 

 

5. This was a common problem, when these cars were actually driven everyday.  Checking and cleaning, adjusting the choke linkage was part or regular tune-ups , that we did back then.

 

intimeold

 

[Bloo]

2 hours ago, intimeold said:

That car, with the original Autolite carburetor, has a multi step fast idle cam; which is controlled by the position of the choke plate.  If the choke is not opening up ( not heating ) the linkage will stay on one of the fast idle cam steps. The choke and fast idle work together, to enrichen the mixture, when the engine temperature is  not up to a specific temperature.  I am saying all of this, not knowing if the Autolite carb is still there. 

Well, if the original Autolite carburetor is there, the two tubes from the choke stove are not there. They should be visible over the rear of the passenger side valve cover, about where that finned breather thing is. With those missing, the choke would never fully open and the engine would never come off of fast idle.

 

3 hours ago, intimeold said:

I would like to see what is under the air cleaner. 

I agree. We can't even make a good guess without knowing.