no throttle response
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Freshman User
Joined: Jun 2003
Posts: 36
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no throttle response
I just picked up an 1981 F-150 Stepside XLT. The truck has got a 302 and 2.75 rear end. This truck has no power at all. Pick up is very slow and Doesn't want to get going untill I am doing 110km. The engine seems to be in decent shape and sounds very responsive when I manually give it gas. Could the rear end be making a good motor feel really sad? Forgot to say C6 auto (slipping?). I know that this truck can move better than she does. Thanks Guys.
Posting Guru
Joined: Mar 2003
Posts: 1,349
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From: Cloud USA
no throttle response
2.75 rear end is really steep for a 302. Remember that you are moving a 4500 pound vehicle. The C6 eats about 30hp off the motor, that isnt helping much. You probably have a 9 inch rear end which would be easy to switch out the gears. I would try 3.73 at the least.
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Joined: Apr 2003
Posts: 1,903
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From: Wyoming
no throttle response
I would agree with the 2.75 gears being pretty tall. If you've got tall tires, that makes it even worse.
Having the aerodynamics of a cinder block, it seems strange the truck only gets going once you hit 110 klicks. Makes gears sound even more likely to be the culprit.
Having the aerodynamics of a cinder block, it seems strange the truck only gets going once you hit 110 klicks. Makes gears sound even more likely to be the culprit.
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Freshman User
Joined: Jun 2003
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no throttle response
Today I installed a new oil filter, air filter, fuel filter, dizzy cap, rotor, plug wires, and a 4bbl High Output aluminum intake manifold. What a huge difference. I think she still needs a little tinkering but I am winning for sure. What is this modulator?
Hotshot
Joined: Oct 2002
Posts: 18,488
Likes: 22
From: The Big, Oregon
no throttle response
The vacuum modulator is mounted on the back right hand side of the transmission. Basically it lets the tranny know how much throttle you are giving the engine, so it can shift accordingly.
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Freshman User
Joined: Jun 2003
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no throttle response
I think that the tranny is fine. I seem to be running fine at 0-60km but lose pickup between 60km and 90km. This truck does not like hills at all. If I am doing 80km and I start up a hill she won't maintain speed but will drop down to 60km with my foot right to the floor. Maybe this engine is more tired than I think.
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