[Bob's66396]

This is the original carb(3139) with the matching Holley intake on my 1966 396/325. I am having some trouble with the carb sticking open after depressing the gas petal down more than 75%. All the linkage is working fine,and any worned parts has been replaced with NOS parts were needed. It does not happen every time,but often enough,and sticks around 2500 rpm's.I do not want to replace it with any other carb, but I can't deal with this sticking open issue. Any one have any thoughts or suggestions,and any rec's? Thanks,Bob

 

[Xplantdad]

I Pm'ed Eric (Vintage Musclecar). He should have some helpful hints!:thumbsup:

 

[Spooky]

Could it be the linkage and not the carb? Just a thought.

Scott

 

[Tom Mobley]

do you have the mechanical linkage with the rod running from the throttle arm to the carb? If so there's an excellent chance it has a bad motor mount on the drivers side, allowing the engine to lift up against torque and bind the linkage.

Don't fool around here, people have died over this back in the 60s and 70s.

 

[Bob's66396]

Linkage is good,so are the motor mounts. I am thinking that maybe the butterfly is sticking. That make any sense? When it sticks,I can knock it back down by hitting the gas petal once or twice...Bob

 

[Tom Mobley]

is there a choke not coming all the way off? fast idle cam popping up?

 

[Vintage Musclecar]

What is the status of the carb--rebuilt/restored or unmolested original?

One of the most common causes of a sticky throttle shaft in a carb is over-tightening the mounting fasteners. The spec for carb studs is no more than 5-6 ft.lbs (60-80 inch.lbs), anything much over that will likely warp/bow the throttle body (if it doesn't snap an ear off first) which can easily cause the shaft(s) to bind.

Also check the condition of the return spring, and make sure it's installed correctly.

Eric

 

[The Devil's advocate]

My neighbor's big block 1966 396 Caprice did that. Upon closer inspection, it had a broken driver's side engine mount, allowing the engine to lift in the frame, locking the linkage down. The carb was OK when the engine was not running, and the only reason we found it was with the engine running and hood up, he locked the brakes, and revved it. I watched the engine go up, the linkage locked, he hit the key to OFF, and it all went back to OK.

Just a suggestion to check the driver's side engine mount.

Regards,

Milton

 

[Guest]

I ran a big return spring w/ a little return spring inside it.

pdq67

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[langss]

I ran a big return spring w/ a little return spring inside it.

pdq67

That's how the return spring is on my car and it came that way.I have a 66 325/396.I'm not saying you don't have some other problem.Just for your info.