Throttle return is a very important aspect of carburation. You want your carb to open all the way on acceleration, buy you also want it to close properly when you lift your foot off the gas pedal.
Here is a short guide on how to install a throttle spring bracket the right way.
Some personal background (if you’re in a hurry, feel free to skip this and get straight to the guide):
I recently replaced my leaky Autolite 2100 carb on my ’65 mustang with a 2-barrel Holley 500cfm street avenger. The switch went well, but i notoced my curb idle RPM woudn’t go below 1500, which is way too high. The car would also drive 30mph without even touching the gas pedal, and stopping at a red light required alot more pressure on the brakes. The old, worn-out return spring which came with the Autolite 2100 was way too weak to pull the mighty Street Avenger back into the fold.
Holley throttle return spring bracket kit installation
Here’s an image of all the separate parts that come with your holley return spring replacement:
But relax, installing this baby is a lot easier than it looks. I’ve numbered the main parts in the kit in the image above for easy reference.
- Start by attaching the main spring bracket (part #1) with two screws. These actualy screw right into the intake manifold (one of the holes goes where one of the corners of your carburetor is attached to the intake manifold. So use the screw from the kit (part #2) for one hole, and the carboretor screw for the second one.
- Pick a set of springs (part #3). This kit comes with two sets, one a bit stronger than the other. I personnaly went for the weaker springs as they were quite sufficient for throttle return.
- As soon as your spring bracket is securely fastened, attach the two springs to the other end of the spring bracket.
- Attach the throttle linkage bracket (part #4) to the other end of the springs using the two small holes.
- Almost done! Using one of the black screws depending on which one fits in your throttle linkage (part #5), the spacer (part #6) and a lug nut (part #7), mount the throttle linkage bracket (part #4, remember?) to your throttle assembly by the large hole.
That’s all folks! Your throttle return springs are now installed!
Before you rush out of the driveway though, please do the following under-the-hood tests first:
- with the engine turned off, move your throttle linkage manually. When you release the throttle, does the throttle linkage swiftly move back to its resting position thanks to the springs?
- repeat the same test with the engine turned on. After pushing he accelerator and releasing it, does the idle rmp immediately go down to an acceptable idle level?
With these tests succesfully completed, try to move your car slowly in the driveway before taking it out on the street for a test drive. Better safe than sorry!
Did this post help you? Do you have experience with this subject? Share your thoughts or ask a question in the comments section!