[Meatsaw]

In my quest to get this rig dialed in, I noticed its only getting 75% throttle at best. After playing with the linkage a bit, I think I found the problem. There is a bunch of flex in the plastic pedal pivot under the dash. It may even be cracked. Anyone have any experience teplacing this thing? Does not look fun...

 

[laser-red-nova]

Just an idea. Are you sure the carpet is not stopping you from getting full throttle??

 

[Meatsaw]

Just an idea. Are you sure the carpet is not stopping you from getting full throttle??

Ya. I wish it was that simple. I can see that plastic piece flexing like crazy

 

[g2072]

If your throttle is being operated by the lokar cable there is adjustment there. I can't tell by the picture about where it is hooked to the carburetor but that matters also. The initial set up of the lokar is a two man operation. You need to be holding the pedal up when measuring the cables and outer sheathing. I will be the first to say that the Lokar set up on a first gen isn't very well designed. I'm using it on my car but they should redesign it so the hole in the firewall isn't directly behind the drivers side head. I have run them on third gen cars but used their pedal assembly also. Without looking at it in person it's hard to tell but it looks like you could gain some pedal my moving the two adjusting nuts back some.

 

[sbc1320]

The plastic pedal piece on the outer firewall can be bought new in plastic or aluminum/metal.

I converted mine to a rod instead of the cable using a bolt in 1st gen. Camaro pedal and a threaded rod I shortened and rethreaded that I purchased from Summit. I did put an engine mount hold down also with this setup.

 

[Meatsaw]

I tried the cable adjustment both ways. It doesnt seem to make much difference as long as all the slack is out. I tried shoving a clothepin under the plastic pivot piece and gained a bit but it is still flexing.

 

[Alf]

When I replaced the plastic rod support that passes thru my firewall I discovered that the replacement plastic piece did not follow the contour of the firewall so care has to be taken to not over tighten it......it will break.

That said, I cutoff the fixed end of the cable under the dash and replaced it with an adjustable cable stop. Dorman makes a nice one, part number 03339.
You can gently take out the cable slack and tighten the cable stop then do any fine adjustments at the carburetor end of the sheath.

 

[Meatsaw]

When I replaced the plastic rod support that passes thru my firewall I discovered that the replacement plastic piece did not follow the contour of the firewall so care has to be taken to not over tighten it......it will break.

That said, I cutoff the fixed end of the cable under the dash and replaced it with an adjustable cable stop. Dorman makes a nice one, part number 03339.
You can gently take out the cable slack and tighten the cable stop then do any fine adjustments at the carburetor end of the sheath.

I ordered an aluminum replacement for the plastic pivot piece from Jegs. Were you able to replace it with the engine in the car?

 

[Alf]

I ordered an aluminum replacement for the plastic pivot piece from Jegs. Were you able to replace it with the engine in the car?

Sorry, I replaced mine during a resto and the engine was out.
Seems to me you could, however.

 

[ccvair]

I did mine with the engine in the car wasn't too bad of a job

 

[Meatsaw]

Well I got er done. The aluminum pivot piece from Jeg’s fit pretty well. I did have to grind the end of the tube down a bit to get the e-clip on. The plastic piece was def cracked when I removed it. This new on flexes way less and should be a lot more durable. Still need that last lil bit to get full throttle though. I have played with all the adjustments on the bracket and cable. I also moved the throttle ball to the upper hole on the arm. It seems like all any of the adjustable points, whether on the cable housing, the bracket on the carb studs, or the one at the ball end can do is take out slack. It seems what I need is more travel.

 

[FrankyM]

Linkage

The higher you go at the carb linkage, the longer gas pedal stroke you will need. On my 66 with rod linkage I ended up drilling a hole in the carb linkage.
The difficulty is that rod or cable applies a straight movement to a linkage that goes through a rotation. Closer to the throttle shaft is a shorter stroke but more curve (ends up going from a horizontal movement to almost a vertical movement).
I also have a 68 Firebird with exactly the same pedal assembly as you. I also cannot get full throttle opening. I found that with the pedal fully depressed, I could pull the cable out of the arm it attached to thus achieving full throttle. I plan on bending the cable connecting arm further away from the firewall. This will result in the gas pedal being farther away from the floor when at rest.

 

[Meatsaw]

Well I got it! There is an L shaped stop where the pedal arm hits the firewall under the dash. I got in there with a dremel and lopped off 3/8” of the downleg. Gave me the range I needed! ??