Throttle Rod To Cable Conversion

[Stepsides 4Ever]

I'm going to convert my throttle rod setup to a throttle cable type from a '71 that I got from the boneyard today. I noticed that the square hole for the cable is about 1 5/16" on center directly below the hole for the plug connection for the tail light/brake light wiring, but I neglected to measure where the mounting for the accelerator pedal is.

Can one of the fine members of this board take a measurement for me, using the center of the plug connection hole as a reference? So, if you were to drop a perpendicular line down the center of both holes (plug connection hole and square hole), how much down and right (facing firewall) does the lower hole of the pedal attachment need to be? In the attached photo, my existing hole is about 1/4" to the right (dotted line) of center, and about 4 5/8" down from center.

Also, the rubber bushing that secures the cable to the cable bracket at the carburetor was split, meaning that the cable won't be secured in the bracket. Is there a fix for this, or do I need to replace the cable? Are they still available?

Thanks!

[Don Smith]

I made an adapter and used the existing bottom hole for the cable setup. You may want to use search function under "throttle cable" a lot of discussion.

[Stepsides 4Ever]

Don, I read your instructions on how you made the swap:

http://www.67-72chevytrucks.com/vboa...throttle+cable

but to be honest I couldn't understand what you were trying to say.

Would you mind rehashing this again?

My plan is to go back to the boneyard this Saturday with some poster board and make a template.

One surprising thing...the bump on the floor where the old pedal used to mount is still there, even though the pedal isn't.

Oh yeah, I do have a digicam...maybe we can work together on documenting this...

[70c10]

That bump on the floor is a threaded stud if I remember correctly.

[bigskiohio]

I installed a cable throttle in a I6 to v8 swap, I used cable off the 1980 . I put isquare hole with die grinder for cable that was easier
than i thought. I used the pedal assembly of of the 80. took awhile to get right position then i just drilled thr 3 holes and bolted it to fire wall. the flat spot is a little tight so you have to compromise a little. will post pic later today. not factory but it works pretty good.

[Stepsides 4Ever]

That bump on the floor is a threaded stud if I remember correctly.

My '70 short step has two threaded ball-end studs that the accelerator pedal pivots on. The bump I was referring to is the cab floor stamping (see attached pic).

[Stepsides 4Ever]

Actually, what I mean to say is this...the donor truck came from the factory with an automatic, but it still had the clutch rod hole that has a patch screwed over it. The bump is still in the floor, even though the floor mounted pedal was not. My conclusion is that the cab (and hence, the firewall) is the same, at least between 1970 and 1971. Others have expressed the opinion that the firewall may be different in the area that the accelerator pedal is mounted to, but it doesn't appear that way to me. Why would they change the tooling for the firewall yet leave the bump and clutch rod hole?

I welded a patch in my clutch rod hole and have yet to finish it smooth with some filler, waiting until I weld up the hole where the original accelerator pedal passes through as well. My plan at the moment is to make a template of that area of the firewall from the donor truck this weekend and see what the differences are. If needed, I will grind, drill out, or chisel off the original weld nuts, fill the holes, and relocate the pedal in as near stock position as I can.

The cable throttle is a great improvement over the throttle rod, IMHO, and worthy of the effort it takes to get it there...but I'm looking for ideas on the best way to do this...

[72c5]

So Stepsides, I have a Q for you...........

I just bot a 69 blazer and it has the rod type accelerator.....it is a bit stifff and not too linear, also has a very short throw....

I think I'm looking for the same thing as you.........does the 71 and up cable setup give a more linear and smoother throttle actuation?

Anybody done this that did not like the results?

[Stepsides 4Ever]

Well, I don't think you can find too many vehicles these days that DON"T have a cable-type throttle. There a fewer disadvantages with a cable system than a mechanical system, and many more advantages. One of the major advantages is a flexible, nearly friction-free system that is far more forgiving about alignment issues.

Another significant advantage is that the pedal is suspended off the floor, which makes it easier to keep the area around the accelerator pedal clean. Have you ever noticed how, when the pedal is mounted to the floor, it seems to collect all the dirt and debris around the base of the pedal? And have you ever had anything lodge behind the pedal when you were driving? Much more likely to happen with a floor-mounted pedal...

[Orange70chevy]

I went out and took a measurement off my cab it looks like 7 inches here is a photo if this don't help let me know the cab is right outside my door I can take more measurements if needed.

[Stepsides 4Ever]

GREAT JOB!!! Now that is what I wish I would have done (with the tape measure). I will take another picture tomorrow.

While you can't see it in my photo, your photo clearly shows that the factory has moved the hole for the plug connector up so that it is almost on the same horizontal line as the firewall grommet at the upper edge of your photo. Judging from that reference, as well as the indented areas at the back of your firewall to the left of the tape measure, the square hole for the throttle cable, at this point, looks like it shoud be above the plug connector on the pre-'71 trucks...at this early stage in the game, roughly about where the firewall retainer plug goes through the firewall above the plug connector in my picture.

So the common locating point can't be the plug connector hole, because it has been moved. The hole from the firewall grommet and the indented areas are in the same location, so they are the new reference points. It also appears that the upper mounting hole that is partially hidden behind the tape measure is about 1/2" to the right center of the square hole, which is in keeping with the way the throttle arm is offset in the nylon block.

Tomorrow I will try to duplicate your setup and post a revised picture, using the center line of the indented area as a reference point and measuring up from there about 2 7/8" for the center of the 1/2" square hole.

Thanks for your help, amigo!!!

[Stepsides 4Ever]

Ok, here's what it looks like to me. I took the center of the indentation to the left on the firewall and measured up about 2 7/8", which puts me right on center of the firewall insulator pad hole above the plug connector hole. It also is 6" above the lower original accelerator arm mounting hole, so the lowermost hole on the new throttle cable would be 1" lower, at 7".

[Stepsides 4Ever]

...and the throttle arm where the cable attaches is pretty close to being at a 90 degree angle to the bend area where it pivots, which looks to be about 7/8" to the center of the mounting hole at the upper right in the attached pic. Sooooo...without bending the arm either left or right, the bracket should go about 7/8" offset to the right of the center of the square hole in your picture, which, if your tape measure is 3/4" wide, looks to be about right. The left-right offset is not really critical, as the arm could be bent to adjust.

[Stepsides 4Ever]

...and here is the stock (I6) throttle arm for reference. Notice that the intended throttle cable location is slightly lower than the lower hole (not shown) in the arm...not that it matters, but just another point of reference.

[Stepsides 4Ever]

...if you have a picture of the accelerator pedal from the inside of the cab looking straight on so I can get an idea of where the pedal rests against the floorboard, it would be very helpful for me to find the left-right location, especially if the cab doesn't have carpet or a mat!

Thanks!

[bpmcgee]

Originally posted by Stepsides 4Ever
Actually, what I mean to say is this...the donor truck came from the factory with an automatic, but it still had the clutch rod hole that has a patch screwed over it. The bump is still in the floor, even though the floor mounted pedal was not. My conclusion is that the cab (and hence, the firewall) is the same, at least between 1970 and 1971. Others have expressed the opinion that the firewall may be different in the area that the accelerator pedal is mounted to, but it doesn't appear that way to me. Why would they change the tooling for the firewall yet leave the bump and clutch rod hole?

I have the factory assembly manual for these, and there is no reference that I've ever seen for two different cab assemblies. Also, any other time there are cab differences (i.e. low vs. high hump), they solve the problem with a patch. Both of these facts support your conclusion Stepsides.

Brian

[Stepsides 4Ever]

Here is where our accel pedal rests. Note that the pedal arm rests on top of the firewall insulator mounting washer, making it impossible for the arm to go all the way to the floor. also, the pedal matches the angle of the bend in the sheet metal on the right as it makes the transition to the floor board.

[Orange70chevy]

Here it is from the inside hope this helps. Again I will be happy to post more photos if needed.

[Bowtie67]

I just replaced my rod setup with one out of a 79, I also pulled the throttle cable from that units as well and it had a I6 engine in it and the throttle cable is real long. Anyone with a cable setup could you post the length of the casing from the dash to bracket from any year would be helpfull. I need to do something about this, it looks like $hit. I would think the V8 cable might be shorter.

[72c5]

Wow! Bowtie that is some fancy looking mill in there! 413 cubes! Your truck must Rip!

[72c5]

Orange70, thanks for the pic! That is very clear.....I'm doing the same thing as Stepsides....very helpful......

[Stepsides 4Ever]

Bowtie67, the cable casing out of a '71 with v8 measures 11" from firewall to bracket. The free travel length is about 3" if you use the stock bracket. There is an excellent thread on making your own custom length cable here.

Orange70chevy, again, thanks for your help! Notice that the bottom hole of the throttle mount is in line with the bottom of the clutch rod hole. Today I will try mocking up the throttle pedal so that the lower hole is down 1" and over 7/8" to driver's side and see what it looks like in comparison to the stock floor-mounted pedal.

[Stepsides 4Ever]

After mocking this up in the 1" down x 7/8" left position, I was unhappy with the accel pedal being too close to the brake pedal. If I moved the assembly further to the right, the upper arm was misaligned with the intended cable hole. I could not move it far enough to the right to make the cable pedal align with the existing floor-mounted pedal...the offset between the intended cable mount hole and the pedal is too much.

Plan B: I have an cable accel pedal out of a mid-70's Chevy truck (see attached pic). Note how Chevrolet resolved this problem by bending the pedal arm. This pedal comes closer to what is needed, but I will still need to heat and bend the arm that attaches to the cable to the driver's side to get it to align with both the intended cable hole and have the pedal in the same position as the floor mounted pedal...

[dubie]

do you guys know if you are able to cut down the existing inline 6 throttle cable to fit a 4 barrel on a 350 that is in the I6 position?

[crazy longhorn]

Dubie, I have cut those cables down.....but its a bunch of work! If you look at the 73 up trucks ,with a 4brl sb, i think you will find a very short cable that will work for you. Good luck,crazyL