Primary Throttle Travel Carter AFB Carburetor

[Daniel B.]

The throttle on my 64 AFB carburetor will only open 1 3/4 inches with the linkage attached but 2 1/2 inches with the linkage removed. This prevents the carburetor from achieving full throttle and opening the secondarys. I replaced all the accelerator linkage except the accelerator lever which I was unable to access. I had the mechanic at the local Chevy Dealership, who was around when these cars were still in their earlier years and certified on these cars look at the problem. He could not find any adjustments on the carb linkage that would allow an increase in the throttle travel. This implies the accelerator lever is the culprit. I saw on another thread that the accelerator lever should just about touch the firewall when the gas pedal is pressed to the floor. Mine is around 2" away from the firewall with the gas pedal full depressed.

I tried to access the lever mounting bolt thru the engine compartment as well as the interior transmission tunnel but still couldn't get to the bolt. Is there any way to access the lever mounting bolt without removing the transmission? Is there even an adjustment on the lever mount or is it a fixed mount position?

I don't hot rod the car but I want it right. Any insight would be greatly appreciated.

[Frank D.]

Re: Primary Throttle Travel Carter AFB Carburetor

This is from the 63 AIM (and assuming 64 is similar, ya just never know) the lever should come very close to the firewall when floored in the cockpit. You have something bent, mis-configured or wrong parts possibly. This all assumes the barrel nut on the carb lever can be adjusted correctly. Read notes #1 and #2 carefully. I assume you've checked under the gas pedal for obstructions, too thick carpet, etc.. A bit of obstruction there can make a significant difference in the engine bay, lever (D) in picture, position AND that the nylon slider on the back of the rubber gas pedal is in place and the metal rod moves fully (and smoothly) across it when operating the pedal.

[Harry S.]

Re: Primary Throttle Travel Carter AFB Carburetor

Please post a picture of the engine side linkage. Firewall to carb. in one picture.

[Frank D.]

Re: Primary Throttle Travel Carter AFB Carburetor

I was assuming his measurement of lever (D) at 2" from firewall was with the carb rod disconnected...he needs to clarify...

[Harry S.]

Re: Primary Throttle Travel Carter AFB Carburetor

I was assuming his measurement of lever (D) at 2" from firewall was with the carb rod disconnected...he needs to clarify...

Bent or Rod B has a problem.

[Ed S.]

Re: Primary Throttle Travel Carter AFB Carburetor

Daniel, its a long shot possibility but I will tell you that I had the same problem with my 64 L76. What I discovered is that the PO attached the grounding strap that goes between the intake manifold and the throttle linkage arm incorrectly. It was attached to the next to last bolt on the manifold - it should have been on the last bolt. The grounding strap is short - so when the gas pedal was "floored" the linkage's travel was restricted by the ground strap. I was getting a little more than half throttle. I gained about 150 HP by moving that strap to the last bolt on the manifold!

[Frank D.]

Re: Primary Throttle Travel Carter AFB Carburetor

Daniel, its a long shot possibility but I will tell you that I had the same problem with my 64 L76. What I discovered is that the PO attached the grounding strap that goes between the intake manifold and the throttle linkage arm incorrectly. It was attached to the next to last bolt on the manifold - it should have been on the last bolt. The grounding strap is short - so when the gas pedal was "floored" the linkage's travel was restricted by the ground strap. I was getting a little more than half throttle. I gained about 150 HP by moving that strap to the last bolt on the manifold!

That's one to remember...!

[Harry S.]

Re: Primary Throttle Travel Carter AFB Carburetor

Like this....

IMG_1199.jpg

[Ed S.]

Re: Primary Throttle Travel Carter AFB Carburetor

Actually, the g/w on my car in that position is considerably shorter than what is in the pic. Not sure if it is the "correct" length g/w for that location. If mine was as long as yours it would not have restricted the throttle linkage travel even if it was attached to the wrong manifold bolt. Have to check the length for correctness. With my g/w on the last bolt of the manifold there is more than enough slack to allow full travel of the throttle.

[Harry S.]

Re: Primary Throttle Travel Carter AFB Carburetor

Actually, the g/w on my car in that position is considerably shorter than what is in the pic. Not sure if it is the "correct" length g/w for that location. If mine was as long as yours it would not have restricted the throttle linkage travel even if it was attached to the wrong manifold bolt. Have to check the length for correctness. With my g/w on the last bolt of the manifold there is more than enough slack to allow full travel of the throttle.

I'll check also.

[Frank D.]

Re: Primary Throttle Travel Carter AFB Carburetor

Here is my 63, have to say, I'm skeptical that this is your problem - the interference from the strap would be pretty apparent I would think.

[Harry S.]

Re: Primary Throttle Travel Carter AFB Carburetor

Found this in a 2011 thread.

John Hinckley (29964)
Beyond Control Poster

Join DateDecember 1st, 1997Posts16,500

Re: 1965 327 accelerator rod ground strap length

Originally Posted by Brian Martinak (47979)
I have a 1965 327/350 car. What is the correct length of the acceleartor ground strap?



Brian -

That's P/N 2981858; it's 5" long overall, 4.3" between hole centers. Has a 1/4" hole in one end, 3/8" in the other end.

[Richard G.]

Re: Primary Throttle Travel Carter AFB Carburetor

Confirm the threaded part of the rod is against the firewall. If installed backwards it can hit the bottom of the air-cleaner.
Don't ask how I know.
Rick