Throttle cable pulley replacement???
12-07-2002, 10:00 AM
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Throttle cable pulley replacement???
I wish I had a picture to better explain myself, but I'll do my best.
Alright, the throttle body butterfly valve has a cable that runs back to the accelerator pedal. At the valve itself there is a pulley/spool where the cable wraps around a few times. When the driver presses the accelerator it pulls the cable, which causes the spool to turn, thus opening the valve to allow air to be pulled into the engine. My question is this; if that spool was replaced with a spool of a larger diameter, and nothing else was changed, would that allow the valve to open faster when the accelerator is pressed? It wouldn't make a difference as far as power goes, but it would result in not having to push the gas pedal in as far.
Here's another question; when the engine is off the valve in completely closed {O or 360 degrees} I assume, when the car is idling the valve is open enough to allow air in the keep the engine firing at that rate... I don't know whether or not the valve is completely open {90 degrees} when the car is at full throttle, is it?
If not, would it make any difference if one could alter the throttle body setup so that is was fully open at full throttle?
Alright, the throttle body butterfly valve has a cable that runs back to the accelerator pedal. At the valve itself there is a pulley/spool where the cable wraps around a few times. When the driver presses the accelerator it pulls the cable, which causes the spool to turn, thus opening the valve to allow air to be pulled into the engine. My question is this; if that spool was replaced with a spool of a larger diameter, and nothing else was changed, would that allow the valve to open faster when the accelerator is pressed? It wouldn't make a difference as far as power goes, but it would result in not having to push the gas pedal in as far.
Here's another question; when the engine is off the valve in completely closed {O or 360 degrees} I assume, when the car is idling the valve is open enough to allow air in the keep the engine firing at that rate... I don't know whether or not the valve is completely open {90 degrees} when the car is at full throttle, is it?
If not, would it make any difference if one could alter the throttle body setup so that is was fully open at full throttle?
12-07-2002, 12:29 PM
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#1. A larger diameter pully would not open the throttle any faster..it would open it slower. A SMALLER diameter pulley would open the throttle faster. Yes they are available, but they don't work very well with cruise control. www.kspec.com has them if I am not mistaken.
#2. The throttle butterfly should be at 90 degrees (horizontal) at full throttle. If your throttle cable is not doing this, you need to take some slack out of the cable.
#3. The throttle butterfly should NOT be 100% closed when off throttle (see above comment). There is an idle adjust screw on the lower firewall side of the TB. That is used to make sure the Throttle Butterfly stays cracked, even when you foot is off the throttle. The Idle air bypass CAN and WILL adjust for a 100% closed throttle, however, It should not have to. Your throttle should stay 2-5 degrees open at "closed" throttle to allow the car to idle.
If you adjust your TB so that the throttle is at 2-5% when your foot is off the pedal, then re-tension the throttle cable, that should allow your TB butterfly to reach the perfect 90 degree angle (horizontal)
#2. The throttle butterfly should be at 90 degrees (horizontal) at full throttle. If your throttle cable is not doing this, you need to take some slack out of the cable.
#3. The throttle butterfly should NOT be 100% closed when off throttle (see above comment). There is an idle adjust screw on the lower firewall side of the TB. That is used to make sure the Throttle Butterfly stays cracked, even when you foot is off the throttle. The Idle air bypass CAN and WILL adjust for a 100% closed throttle, however, It should not have to. Your throttle should stay 2-5 degrees open at "closed" throttle to allow the car to idle.
If you adjust your TB so that the throttle is at 2-5% when your foot is off the pedal, then re-tension the throttle cable, that should allow your TB butterfly to reach the perfect 90 degree angle (horizontal)
12-07-2002, 10:44 PM
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I knew the throttle was open when the car is idling, a small amount to let enough air in to keep the engine firing.
And I was trying to determine whether it was a large or small pulley that would allow the valve to open faster when the accelerator is applied, obviously I came up with the wrong conclusion.
I don't have cruise control on my car, so that wouldn't be an issue.
And I was trying to determine whether it was a large or small pulley that would allow the valve to open faster when the accelerator is applied, obviously I came up with the wrong conclusion.
I don't have cruise control on my car, so that wouldn't be an issue.
12-12-2002, 03:08 AM
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You adjust the throttle cable tension via the two nut screws that hold the Cable to the intake manifold. You can "adjust" the cable forward and back to add or remove slack. You want to have about 1/8" of slack in the cable, but you DO NOT want the cable 100% tight.
The screw in the Throttle body itself is to set the idle.
The screw in the Throttle body itself is to set the idle.