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| Softer Throttle Response for Fuel Injected Motors | Short Cuts | ||||
| by: Joshua Lowenstein edited by: John Nutter |
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Easy Fix Hurky-Jerky Throttles for Less than $5.00
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| The throttle lever after the modification. |
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| The throttle lever before the modification. |
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| The finished 'add-on' lever. |
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| This is where to shim the throttle level bracket with washers. |
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| Check for air cleaner clearance when you are finished. |
Does it seem you have to push too hard while starting off, only to have the engine rev too fast and cause a jerky take off? Wouldn't it be nice to have a feather-smooth throttle? Having jerky throttle response is bad enough for day to day street driving, but is downright dangerous on the trail. Tip-toeing gently through a rocky section of trail? HA!
With that "on or off" throttle you are either spinning your tires, broken by the side of the trail, or just feel totally out of control while attempting what should be a gentle glide over those rocks.
The solution involves a simple leverage angle adjustment to the Holley Projection 2bbl. This repair also applies to any GM throttle body, as well as some carburetors. The vehicle is a 79 CJ7 with a 360 cid engine.
The throttle body itself is not the problem, the way it works in most applications is. The leverage pressure exerted at the point of opening the throttle is too little, thus causing the stiff feel.
While testing the opening of the throttle plates at the throttle lever, the thought that comes to mind is that the return spring is too tight. A standard tension return spring is what should be used for proper speed of deceleration. The fix involves changing the angle of how the cable pulls the lever. It's like using a bigger hammer to pound a nail, but without the banging. In this case it's being smarter than the nail.
The height of the lever needs to raised about 3/4-7/8 inch. You might think that's not very much, but it makes a world of difference at the pedal.
The modification might involve some drilling of holes in the throttle lever for some applications other than Holley Projection.
In the case of the Holley tbi the holes are right there, you just need a small piece of mild steel strap, 1/2" wide 1/8" thick and 3 1/2" long. A drill and 1/4" bit to make the mounting holes and a vise to make a couple of slight bends. Note the bends and the offset of the holes. Two 1/4" 20tpi by 1/2" long bolts/nuts and a dab of silicone to keep the nuts from loosening up.i
Some problems might be encountered while doing this modification. Too short of a throttle cable can be cured by shimming under the bracket that retains the cable with washers to raise it. This corrects for the change in cable length. Slight oblonging of the bracket mounting holes can work too. In an auto transmission application, a detent adjustment may need to be made.
The other concern is air cleaner interference. Adding a taller spacer under the air cleaner (providing hood height is available) can solve this. A slight tap with your ball peen hammer just might get you what you need if the lever just barely touches the bottom of the air cleaner. I recommend at least 1/4" gap between the top of the lever and the bottom of the air cleaner assembly.
Have a helper push the pedal while you check for the free movement of the throttle, before test driving the vehicle on the street. Check for clearance and binding with the air cleaner both off and on. You will know immediately you're sucessful when the effort to press the gas pedal is cut in half.
What you will "feel" is a softer, kinder, gentler gas pedal that will make tip-toeing through the rocks a pleasure.
Good luck, good wheeling and be safe!!
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