Return to idle on '63 FI - weak spring?

[Michael B.]

Recently restored L84 '63. The idle return spring on the throttle linkage seems to weak to always return the throttle to idle. Is this a common issue?

I am also noticing there doesn't seem to be enough travel clearance for the linkage to go from idle (1000 RPM or so) to WOT. The lever is running into the ignition support bracket at idle and then the firewall at WOT. At the moment I have it set up to not achieve WOT, but obviously I'd like to fix that.

Any help would be appreciated.

Mike

[John D.]

Re: Return to idle on '63 FI - weak spring?

Mike, '63's are very sensitive to having the correct accelerator return spring. Some of the repro springs start off working just fine but quickly loose it and are too week.
The NOS springs you see for sell are typically NOS service replacement springs. They are not as good as one that came with the car. Work fine on a '64-65 but not always on a '63. Why? IF one were to study the two different bellcranks you would see the geometry or configuration of the two is different.
Another problem with '63 springs is an age old argument which I am not going to get into here except to say the "black' spring or natural spring is much longer than a typical 63 spring. Hence the spring tension just isn't there.
You need a good spring. Also make sure you have the accelerator return spring bracket on correctly.
Need pics to show the other problem although you description is decent. Do you have the accelerator swivel on correctly?
Do you have the correct accelerator rod? One of the repros is bent incorrectly and one of them is dead nuts and even has the MW logo on it.
Does you rod have a MW logo? Is your bellcrank bent. What's WOT? Oops. Wide open throttle?
The guys could probably help you quickly if you have pics. Or send me a pic orr two at johndegreg@aol.com if you cannot post on the DB here. John

[Michael B.]

Re: Return to idle on '63 FI - weak spring?

John, here are some pics...hopefully this helps?

Idle position has little clearance to ignition support bracket.


WOT - arm not touching firewall in correct spot. Its grounding out below the tab on the arm.


I believe the throttle rod has the MW on it.

[John D.]

Re: Return to idle on '63 FI - weak spring?

Mike, The spring bracket and spring hookup appear to be correct. Question. Gently touch the spring. Side to side. Does it have much tension?
You might have a weak repro spring. But forget about the spring for a moment.

You have several issues going on with the round accelerator rod.
#1. The rod is bent/bowed. See how it's bowed at the threaded end. When I look at my fuel car the rod rather horizontal. Yours is going down hill.
#2. Your swivel is choking the accelerator linkage up big time. Forcing it forward toward the radiator.
Back the swivel off toward the firewall. Not every car has the same dimensions but here's what my 63 FI car has.
From the back side of the swivel there is about a tad over 27/32" of thread showing.
#3. The bellcrank to accelerator rod blackened retainer. You appear to have a replacement that may be causing the linkage to bind.
Need a closer pic of it please Mike.
#4. Temperature sending unit loom goes on the passenger side Mike. I

Recap: Easy to see why you are having all kind of interference problems Mike. I don't thin k it has anything to do with the shielding bracket.
I hope you have the correct firewall linkage.
See your distributor tag in the background Mike. The front side of your flat rod should align with the back side of the tag. Your rod is going forward too much/big time.
Email me at johndegreg@aol.com I will send you pics as I never learned how to put pics up here. Never even tried. For this I apologize and promise that after Corvette Carlisle is over I will work on it. Have to since Brian Futo flew the coop and now I have his old job. hahaha.

[Bob J.]

Re: Return to idle on '63 FI - weak spring?

Michael,
what letter is stamped into the lever coming off the firewall? It should have a letter stamped on one side at the top. It should be letter H.
Bob J

[John D.]

Re: Return to idle on '63 FI - weak spring?

Thanks Jorjorian. Forgot about that. The "H" is stamped on the distributor side of the lever. Right below the hole for the clevis assembly.

Qt: RJ and others: Does a carburetor engine have the same lever as an FI car? I used to know but forgot. John

[Joe R.]

Re: Return to idle on '63 FI - weak spring?

John,

Here's a pic of a 63 Accelerator Lever. As you know there was at least 7 different levers from 63-67. Some available and some not! The one on the right is for a 63 with the "H" at the top. The other, well at least it's an accelerator lever.

JRDSCN4304.jpg

[John D.]

Re: Return to idle on '63 FI - weak spring?

Joe, So '63 is all on its own. Jorjorian reminded me that all '63's levers are the same no matter what HP.
Heard your midnight call but I was sleeping.

[Michael G.]

Re: Return to idle on '63 FI - weak spring?

Mike, here's a pic:


Screen Shot 2015-08-09 at 10.09.09 PM.jpg

[Michael B.]

Re: Return to idle on '63 FI - weak spring?

Ok, thanks for all the info guys!

The accelerator lever is the '63 variant, the one to the right in the pic from Joe Ray above. It has the H stamped on it on the passenger side.

The rod is bent in both the side view and the top view (shown towards the bottom of the photo added below). It appears to me that in the top view the accelerator lever and the rod are not in the same cross car location, and that the rod is offset in the top view to account for that.

I measured the the length of threads aft of the swivel attachment to the accelerator lever, and it measures 1.2". Longer than what you stated it should be. However, I have it adjusted there because its getting nowhere near WOT (wide open throttle) with it adjusted shorter than that. This is the shortest it will adjust, still achieving close to WOT while still having almost enough return spring force to bring it back to idle.



Thanks,
Mike

[John D.]

Re: Return to idle on '63 FI - weak spring?

Pics of my '63, the LWC linkage.
Note nice NOS blue spring.
Note original sleeve with hard rubber insert with nice logo GM then opposite GM it reads JR or just an R with wild loop and #52.

[Joe R.]

Re: Return to idle on '63 FI - weak spring?

Hey John, Did the 63 team deduct for that incorrectly installed and incorrect part on the accelerator rod???????? The old LWC don't look top flight in that pic.

JR

PS I can get the correct parts on the way via express mail. Free to you buddy!

[Timothy B.]

Re: Return to idle on '63 FI - weak spring?

Michael,

The lever on my November built 63 hits the firewall at the lower bend just like the second pic in your post #3. The lever is the original 63 part with the stamped H and I have even tried another used 63 lever with the same result. The inside pedal sits higher IMO because of this, all I can figure is that's the way the bellcrank is riveted to the firewall. Also interesting that the lever changed in 1964 for all engine options.

Does anyone else have this issue, my car has the 300hp engine and could never figure this one out..

[Dan H.]

Re: Return to idle on '63 FI - weak spring?

Is that a star washer on JDs ground strap bolt to the throttle lever?

[John D.]

Re: Return to idle on '63 FI - weak spring?

Is that a star washer on JDs ground strap bolt to the throttle lever?

Hey Holstein. You gots to give nice judges some bait to keep them happy you know. Please refer to page 94 in the 6th edition. Ground strap. Says external tooth washer. Yeah
Meanwhile you guys can quit emailing me about my nice star washer as leaving it on. Just for fun. Yes I know my distributor oil line should be black or dark. But it ain't leaking so not messing with it.
Got 5 emails so far complaining about the star. Cool. Nice to see you like my nice pics though.
Now I have to learn how to post multiple pics at the same time. Don't tell me. I want to figure it out for myself. JD