Linkage might kill carbs !!

[whitelightning777]

An interesting & disturbing thing happened.

This morning, my gas pedal somehow fell off and I put it on. I had to lift the linkage up just a little bit higher then it normally goes to flip it back right side up instead of upside down.

So, thinking nothing of it, I start up the cougar to go to work to make sure it doesn’t fall off again.

When the engine warms up, the same symptoms that induced me to change to my new Edelbrock carb from the old one have returned.

I still have to investigate in daylight to make sure it’s not a coincidence and something else, but I think I either killed it or knocked it out of adjustment big time.

The link between the carb and the throttle pedal is a solid piece of what looks like 1/8th inch rebar with a series of right angle bends.

The point is that if the gas pedal is raised, the primary linkage will be rotated counter clockwise well past the normal stopping point, thus creating excessive torque on the primary shaft.

If cables attached the carb to the gas pedal shaft, there would’ve been some slack in the linkage which would protect it from damage.

With the throttle fully held down, I could have set it so it would fully open. When the throttle goes up, the carb shaft the the throttle should lift independently.

That’s not how it is. It’s one solid link. I better find out how the OEM one works. This is probably a serious mistake by whoever restored it. The thing doesn’t look stock.

Hopefully, I’ll make it home from work. It probably looks like there’s a 50-50 chance I have to get another carb. The linkage looks ok, but it probably isn’t.

Excessive torque in the wrong direction and carbs don’t play well together.

In any event, the old Holley carb has a new home to go to. The one I have now will either be fixed or stored for spare parts.

Wish me luck.

[Smilodon]

There should be finite limits to gas pedal travel, but my first thought on this is that perhaps the linkage wasn’t slotted into the right position on the carb in the first place? Properly adjusted, the pedal limits and carb limits should coincide, so you’re not over-stressing the throttle plate assembly on either end.

The factory linkage, while nothing fancy, offers good positive feel and a very direct connection. I’ve never had mine bind. It would take a tremendous amount of force to jam the throttle blades beyond their normal travel, at least on my setup! Further, the skinny threaded rod involved in throttle actuation is not that beefy. I’d expect it to flex or even bend if you tried exerting that much torque on the carburetor by pulling up on the pedal.

Is it possible that the mounts for your gas pedal are loose or damaged, and that’s causing trouble?

I can say from personal experience, I will never use a cable pull throttle linkage again, if I have the choice. It was nothing but trouble when I had one on my car, and the simple, plain-Jane, boring el-cheapo factory linkage is superior in every way.

I hope your problem turns out to be a simple one! Definitely wishing you good luck. =)

[robert_campbell]

Some pictures would be a huge help. Smilodon is right on. Your stock linkage is the best and simplest design for your car. You need two people to properly adjust it. Remove the linkage from the carb. Have one person in the car hold the gas pedal comfortably on the floor. No need to mash it. Hold the carb in the wide open position and adjust the rod so it slips into the clip or hole on the carb. Done.

Also Smilodon is correct. The hole on a Holley or Edelbrock may not work well with the old style clip. You may need to drill a small hole in the rod for a cotter key to secure it to the carb.

Pics dude!!

Rob

[whitelightning777]

It’s not factory!! It’s basically rebar with one spring and no stops.

There is literally nothing like the factory linkage left what so ever. I’m going to repurpose a section of manual choke cable, possibly double wound or a really stiff throttle return spring as a stand in. The fact that there is only 1 throttle return spring also needs to change.

The fellow was going for road feel and the pedal DOES feel precise, but if getting something under it grenades the carb, no good.

In fact, it wouldn’t surprise me if that’s what killed the last carb on the vehicle!!

[whitelightning777]

Very well. There’s just no way this is OEM, can’t be.

[whitelightning777]

I got lucky. I was able to readjust both the fast idle and cold idle. The vents still switch and the headlight doors still work. If it had a vacuum leak, it isn’t that bad.

Wow was it knocked for a loop though!!

I also put a new Edelbrock air cleaner on so I can actually adjust it should misbehavior arise.

[xr7g428]

That sure looks like the stock linkage. The spring arrangement is not stock but neither is the carb so that is expected. Usually on a Ford installation the driver side fuel inlet is used just because there is less in the way on that side. You might want to see what is holding the rod at the carb. Stock used a special clip. On an Edelbrock you might need to drill a very small hole and use a cotter pin to keep it from coming lose.

[robert_campbell]

Drill a small hole as I said earlier to attach to the carb. Yes, it is a stock linkage. Adjust it properly and it is the best Ford linkage ever made. Simple and totally trackable. Thanks for the pic.

Rob

[Smilodon]

The main problem most people have with aftermarket carbs using this setup is that sometimes the travel of the throttle lever doesn’t match the travel of the hole they choose. Obviously that’s not a good compromise.

If the hole for the primary linkage is too close to the shaft in the carb, then it doesn’t move far enough, so you bind at ‘closed’ or ‘wide open’. If it’s too far out, then you can’t adjust enough to ever get the butterflies fully open. The ‘easy’ way to correct this would be to measure travel of the throttle link bar (with it disconnected) and then test different holes on the carb to find one that has similar full travel from closed to open. Once you get there, you can adjust the length of the link bar by screwing it in or out, and make the end of it match the hole you chose.

If none of your carb’s holes are appropriate on the primary linkage, it’s usually not too hard to fabricate a small metal plate and attach it, or just drill a new hole where you want it. You want the hole to be above the butterfly shaft, and remember, you only need about 90 degrees of travel, so you don’t have to be ultra-precise about where it is on the plate except for its fore-and-aft motion.

The very worst choice for ‘fixing’ this problem is a cable pull pedal. Second worst would be an aftermarket throttle linkage with more complication, expense, and the potential to jam or bind on you later. I’ve seen a lot of sweet looking billet setups that cost a ton, and only cause problems.