Throttle linkage bell crank

[Gas Pig]

I’m a little perplexed on this V8 throttle linkage mechanism and throttle bell crank. Over the years I have seen guys omit the crazy linkage mechanism and just use the throttle linkage bell crank.

I know some of the parts houses carry throttle bell cranks but they seem like they have a little different geometry on their arms. It appears the aftermarket bell cranks don’t have any offset on the arms while the original bell cranks I have seen have a pretty large off set on arms.

Anyways I want to omit throttle mechanism and only run with the throttle bell crank by itself. What should I look for in the way of new and used parts?

Thanks Jeff

 

[BronCowie]

It was an engineering marvel at its time, point being to lessen the effect of body to frame flexing to give smoother throttle response on rough terain. At least, thats my understanding. Those here that are more knowledgeable can correct me if I got that wrong. Anyway, I elliminated mine years ago and installed a throttle cable in its place... works great for street driving anyway.

 

[DirtDonk]

I think that’s correct, or at least that’s what I’ve heard as well.
But remember even Ford eliminated it in 73 so there doesn’t seem to be any downside to it.
So unless you lose some aspect of the pedal to throttle ratio, I don’t see any reason not to.

 

[jamesroney]

I think that’s correct, or at least that’s what I’ve heard as well.
But remember even Ford eliminated it in 73 so there doesn’t seem to be any downside to it.
So unless you lose some aspect of the pedal to throttle ratio, I don’t see any reason not to.

Gonna agree to disagree on a small detail. A similar compensation device was installed on Ford Intermediates with unit-body construction. So @BronCowie is mostly right...but absent a "frame" the design intent would be to accommodate engine to body variation.

I always thought it was to mitigate the unintended acceleration associate with engine torque. But body motion makes sense too. Moving the linkage from a "pull" to a "push" at the carburetor can also reverse the effect, and *almost* prevents runaway acceleration in the event of a failed left side engine mount. I can guarantee you that a broken left motor mount in a 68 Montego allows enough flex to pop the clutch z-bar off the pivot ball, and wedge itself against the block and hold the engine against the hood and provide full throttle. The now pivotless z-bar prevents clutch disengagement, and the vehicle propels itself in whatever gear it is in. Full throttle eliminates manifold vacuum, so power braking is defeated. The panic that ensues during the time it takes for the senses to connect to the brain and determine that the clutch pedal is worthless, the brake pedal is worthless, and the gas pedal is stuck to the floor results results in the incorrect conclusion that the appropriate course of action is to force the gearshift into neutral. This results in the vehicle coming to a stop, but the engine has run away. If this happens in close proximity to the garage you were just leaving…your father will suddenly appear, screaming something at you, which you cannot hear over the pandemonium. “Shut it off” can be mistaken for “get out of the way, you idiot..” which is impossible when your father is banging on the very door you need for egress. Precious seconds are lost trying to open the door. This may be the first and only time that the universal “throat slash” gesture has ever been successfully put to good use. The engine racing, the running and shouting, is apparently quite entertaining if you have an older brother. Evidently, comments informing you of what you should have done are especially comical. The takeaway is that a 2bbl Ford 302 will run for a remarkably long time at full throttle in neutral. And yes, next time I will just turn off the key.

Obviously, a throttle cable also negates the effect, and a longer pivot length (like the early mustang rod also minimizes the effect. A simple safety rivet in the left motor mount seems to be the universal solution.

 

[Madgyver]

i built my own. On Taz's Firebronco and on my yellow77 with the 393 Clevor, unfortunately my posting pics here option expired..
pivot point changed and affected ratio in a good way.

 

[Qumanchew]

Gonna agree to disagree on a small detail. A similar compensation device was installed on Ford Intermediates with unit-body construction. So @BronCowie is mostly right...but absent a "frame" the design intent would be to accommodate engine to body variation.

I always thought it was to mitigate the unintended acceleration associate with engine torque. But body motion makes sense too. Moving the linkage from a "pull" to a "push" at the carburetor can also reverse the effect, and *almost* prevents runaway acceleration in the event of a failed left side engine mount. I can guarantee you that a broken left motor mount in a 68 Montego allows enough flex to pop the clutch z-bar off the pivot ball, and wedge itself against the block and hold the engine against the hood and provide full throttle. The now pivotless z-bar prevents clutch disengagement, and the vehicle propels itself in whatever gear it is in. Full throttle eliminates manifold vacuum, so power braking is defeated. The panic that ensues during the time it takes for the senses to connect to the brain and determine that the clutch pedal is worthless, the brake pedal is worthless, and the gas pedal is stuck to the floor results results in the incorrect conclusion that the appropriate course of action is to force the gearshift into neutral. This results in the vehicle coming to a stop, but the engine has run away. If this happens in close proximity to the garage you were just leaving…your father will suddenly appear, screaming something at you, which you cannot hear over the pandemonium. “Shut it off” can be mistaken for “get out of the way, you idiot..” which is impossible when your father is banging on the very door you need for egress. Precious seconds are lost trying to open the door. This may be the first and only time that the universal “throat slash” gesture has ever been successfully put to good use. The engine racing, the running and shouting, is apparently quite entertaining if you have an older brother. Evidently, comments informing you of what you should have done are especially comical. The takeaway is that a 2bbl Ford 302 will run for a remarkably long time at full throttle in neutral. And yes, next time I will just turn off the key.

Obviously, a throttle cable also negates the effect, and a longer pivot length (like the early mustang rod also minimizes the effect. A simple safety rivet in the left motor mount seems to be the universal solution.

Haha, great story!

 

[Gas Pig]

Gonna agree to disagree on a small detail. A similar compensation device was installed on Ford Intermediates with unit-body construction. So @BronCowie is mostly right...but absent a "frame" the design intent would be to accommodate engine to body variation.

I always thought it was to mitigate the unintended acceleration associate with engine torque. But body motion makes sense too. Moving the linkage from a "pull" to a "push" at the carburetor can also reverse the effect, and *almost* prevents runaway acceleration in the event of a failed left side engine mount. I can guarantee you that a broken left motor mount in a 68 Montego allows enough flex to pop the clutch z-bar off the pivot ball, and wedge itself against the block and hold the engine against the hood and provide full throttle. The now pivotless z-bar prevents clutch disengagement, and the vehicle propels itself in whatever gear it is in. Full throttle eliminates manifold vacuum, so power braking is defeated. The panic that ensues during the time it takes for the senses to connect to the brain and determine that the clutch pedal is worthless, the brake pedal is worthless, and the gas pedal is stuck to the floor results results in the incorrect conclusion that the appropriate course of action is to force the gearshift into neutral. This results in the vehicle coming to a stop, but the engine has run away. If this happens in close proximity to the garage you were just leaving…your father will suddenly appear, screaming something at you, which you cannot hear over the pandemonium. “Shut it off” can be mistaken for “get out of the way, you idiot..” which is impossible when your father is banging on the very door you need for egress. Precious seconds are lost trying to open the door. This may be the first and only time that the universal “throat slash” gesture has ever been successfully put to good use. The engine racing, the running and shouting, is apparently quite entertaining if you have an older brother. Evidently, comments informing you of what you should have done are especially comical. The takeaway is that a 2bbl Ford 302 will run for a remarkably long time at full throttle in neutral. And yes, next time I will just turn off the key.

Obviously, a throttle cable also negates the effect, and a longer pivot length (like the early mustang rod also minimizes the effect. A simple safety rivet in the left motor mount seems to be the universal solution.

Yeah that is a great story!

 

[Dne007]

I think that’s correct, or at least that’s what I’ve heard as well.
But remember even Ford eliminated it in 73 so there doesn’t seem to be any downside to it.
So unless you lose some aspect of the pedal to throttle ratio, I don’t see any reason not to.

Just curious, but what was the bell crank replaced with? I'm just using a universal throttle kit for now and is working just fine.

 

[DirtDonk]

They didn’t actually eliminate the bell crank so I misspoke. What they eliminated was the triple jointed cantilevered wacky Jakie thingamajig bolted between the firewall and the intake manifold.
The standard pedal and bell crank remained with a direct rod to the carb linkage.

There are discussions here with pictures showing the linkage on 73 and later broncos. You can still see the two dimples in the firewall where they did not drill the holes.

 

[BronCowie]

They didn’t actually eliminate the bell crank so I misspoke. What they eliminated was the triple jointed cantilevered wacky Jakie thingamajig bolted between the firewall and the intake manifold.
The standard pedal and bell crank remained with a direct rod to the carb linkage.

There are discussions here with pictures showing the linkage on 73 and later broncos. You can still see the two dimples in the firewall where they did not drill the holes.

"the triple jointed cantilevered wacky Jakie thingamajig" ... Love it!

 

[Gas Pig]

They didn’t actually eliminate the bell crank so I misspoke. What they eliminated was the triple jointed cantilevered wacky Jakie thingamajig bolted between the firewall and the intake manifold.
The standard pedal and bell crank remained with a direct rod to the carb linkage.

There are discussions here with pictures showing the linkage on 73 and later broncos. You can still see the two dimples in the firewall where they did not drill the holes.

Yep that is how my firewall looks like. What I been mixing up in my understanding. On my 72 it had the “wacky Jackie thingamajig” but not realizing that ford simplified it in 73. When I saw ‘73 and later bronco I wasn’t sure if the simplified version was factory or the owners of the Bronco did it themselves.

But now I know! That’s what happens when you just spend most of my time building 66’s. So, I just have to broaden horizons!

 

[nvrstuk]

All I know is mine worked perfect for 20 yrs and then long travel suspension came out in the mid '90's and when I was all twisted up my idle speed would increase with the stock bell crank. Little bit hazardous when unexpected.

I immediately removed it and went with a cable throttle. Never had another issue with body flex causing any rpm issues.

 

[1970 Palmer]

All I know is mine worked perfect for 20 yrs and then long travel suspension came out in the mid '90's and when I was all twisted up my idle speed would increase with the stock bell crank. Little bit hazardous when unexpected.

I immediately removed it and went with a cable throttle. Never had another issue with body flex causing any rpm issues.

LOL.....Likely one of the reasons Ford finally got rid of mechanical brakes on their vehicles.

 

[jamesroney]

All I know is mine worked perfect for 20 yrs and then long travel suspension came out in the mid '90's and when I was all twisted up my idle speed would increase with the stock bell crank. Little bit hazardous when unexpected.

I immediately removed it and went with a cable throttle. Never had another issue with body flex causing any rpm issues.

I think it's funny that the first 1966 Bronco's were all equipped with a cable throttle...

 

[nvrstuk]

I think it's funny that the first 1966 Bronco's were all equipped with a cable throttle...

I think those cable throttles (my 68 dash has one) were used for all the farm type implements that Ford & the aftermarket had available for the EB's.

PTO driven post hole auger, PTO winch, etc I used mine all the time (I had a PTO winch) but never used it when moving.

The hand throttle would allow you to increase the engine rpm instead of having to use the manual choke or jam something against the throttle pedal to increase the pto speed.

 

[jamesroney]

I think those cable throttles (my 68 dash has one) were used for all the farm type implements that Ford & the aftermarket had available for the EB's.

PTO driven post hole auger, PTO winch, etc I used mine all the time (I had a PTO winch) but never used it when moving.

The hand throttle would allow you to increase the engine rpm instead of having to use the manual choke or jam something against the throttle pedal to increase the pto speed.

Sorry. I meant cable actuated foot throttle. All of the first 66 Broncos were 6 cylinders, and the 6 cyl had a cable operated accelerator pedal.

 

[Oldtimer]

I used the 6 cylinder accelerator cable when I installed 351W in my 68.
The “wacky Jackie thingamajig” would not clear the valve cover.

 

[nvrstuk]

OK- the hand throttles are cool tho...