When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
On my last drive of last season, my engine would not come down on RPMs reliably when pressing in the clutch. So I thought to replace the throttle return spring. Based on the work I have been doing to continue to improve this car, I'm finding lots of things that "aren't right." So, I ordered the correct spring from a Corvette online parts dealer so now I know I have the correct spring. I just put it in, where the old one was, and notice the spring is really close to the mechanism just above it. It is not touching, but seems too close? there are a few other holes in the bracket, but when I look at the AIM, that bracket doesn't look the same...so possible I have the wrong bracket (where the accel cable connects to the carb)? What are your opinions...is my spring location ok? Should I move it to one of the other holes? Is my bracket wrong?
The car is 1970 with 350/350 (L46) motor. Q-jet carb.
(sorry the pictures are so big, not sure how to change that)
On my 69 L46 the return spring is hooked up to the larger hole in the outer bracket and it works fine . Your bracket looks as the same as what`s on my carb .
Steven
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
Since your not going NCRS , I would get a double spring in case that one comes off. Its a safer choice. As for location that looks correct. As you move the throttle through its throw you should see if it contacts the throttle mechanism. IF it does you can make and extension to bring it down below the throttle clamp
You may want to check the butterflies to make sure they are closing all the way at idle.
It is common and they may need to be adjusted.
If that is the original carb, it could be time for a good rebuild.
Don’t replace it if it is the original.
It’s better than anything aftermarket or any remanufactured.
You may want to check the butterflies to make sure they are closing all the way at idle.
It is common and they may need to be adjusted.
If that is the original carb, it could be time for a good rebuild.
Don’t replace it if it is the original.
It’s better than anything aftermarket or any remanufactured.
Thanks for the comments. I actually had the engine rebuilt 2 years ago. Previous owner was racing the car and had a different intake and a Holley carb on it. When I had it rebuilt, I put a new, more appropriate aluminum in take on, and then sent the original Q-jet carb to LARS to be re-built and installed that. Have been happy with the performance!! But I have to say now I'm afraid to touch/adjust anything on the carb as I'm sure Lars had it set right.
For a second return spring, (again, not NCRS) there is a thermostat housing, probably duplicated by several manufacturers, that has an eyelet cast into it to hook another return spring into it.
You can also do the spring-inside-spring in your current location. I had trouble finding that in the correct length though.
Thx - can you point me to the proper "dual" spring that has been mentioned?
At Summit Racing search box enter:
SUM-G1320
$7.99
You don't need anything fancy. Just something that closes the throttle in the event of one spring failure.
You can also look on EBay Motors. Summit & Jegs sells same stuff on there but free shpg.
Last edited by HeadsU.P.; May 18, 2023 at 08:10 AM.
Thanks for the comments. I actually had the engine rebuilt 2 years ago. Previous owner was racing the car and had a different intake and a Holley carb on it. When I had it rebuilt, I put a new, more appropriate aluminum in take on, and then sent the original Q-jet carb to LARS to be re-built and installed that. Have been happy with the performance!! But I have to say now I'm afraid to touch/adjust anything on the carb as I'm sure Lars had it set right.
In that case, my first contact would have been to contact Lars!
I would also be afraid to touch anything on that carb in fear that I would mess up what he did.
You may want to check the butterflies to make sure they are closing all the way at idle.
It is common and they may need to be adjusted.
THIS! So... I was messing with it tonight and as I activated the throttle linkage, the butterflies don't move at all! They don't close when releasing back to idle...and, when I engage the throttle all the way, the secondary doesn't open up! What has happened? This could explain why my engine wouldn't come off fast rpm when I pressed in the clutch. I thought it was the return spring issue (maybe not strong enough, etc)...but now I think this is really the issue? I had Lars rebuild it 2 years ago and it ran fine last summer...where do I start?
Contact Lars!
It could be something got gummed up during the winter do to the terrible fuel we have now days, or it may need a simple adjustment.
Thanks - I only run non-oxy fuel, to help keep things from getting gummed up...and, I think the issue started last fall, before it sat for the winter. I started a new thread with a video link and also sent it to Lars.
You only need to use non-Ethanol gas once a year. And that being the last tank full just before long-term storage.
You are wasting hundreds of dollars burning that expensive fuel all summer for nothing.
The key to NOT having issues, is to keep the fuel circulating & fresh. In other words, drive it. Ethanol is fine for that.
Ethanol does not do well in storage. Nor does any carb parts sitting in it.
Throttle return spring question
