Newbie needs accelerator help

[BRADVAN 10]

New to the site though I have been reading and using the search engine, but now need to ask a few questions about my son's 69 coupe.

To let you know my experience level, I have a 65 Fastback street rod I'm finishing, mildly built 302, C4 transmission, 8 inch rear. I watched and kind of helped rebuild the 302, installed a different torque converter in the C4 (but ruined a set of seals in the process), put a disc brake conversion on the front (but had to take it to a shop cause I couldn't get them bled), installed new uphostery, headliner, carpet, dash pad etc with no problems.

There is a Edelbrock 1406 on my son's 69 coupe. The 302 came from a 66 Mustang (before that who knows) and has Offenhauser 360 intake, looks like stock non-adjustable heads, maybe a mild cam?

Heres the problem. The accelerator is very stiff and won't move, then all the sudden gives away and you spin the tires. Once that happens you can drive, but the pedal still seems stiff making acceleration jumpy. The throttle cable moves freely, although it has been broke right on the carb end and is about an inch short, so I built a metal extension that fits over the 1/4 inch carb stud and this all moves freely.

Other than possibly needing a new cable, what else could make the accelerator so stiff? My son turns 16 in Sept and he really does not need a car that burns the tires. Thanks.

[BRADVAN 10]

New to the site though I have been reading and using the search engine, but now need to ask a few questions about my son's 69 coupe.

To let you know my experience level, I have a 65 Fastback street rod I'm finishing, mildly built 302, C4 transmission, 8 inch rear. I watched and kind of helped rebuild the 302, installed a different torque converter in the C4 (but ruined a set of seals in the process), put a disc brake conversion on the front (but had to take it to a shop cause I couldn't get them bled), installed new uphostery, headliner, carpet, dash pad etc with no problems.

There is a Edelbrock 1406 on my son's 69 coupe. The 302 came from a 66 Mustang (before that who knows) and has Offenhauser 360 intake, looks like stock non-adjustable heads, maybe a mild cam?

Heres the problem. The accelerator is very stiff and won't move, then all the sudden gives away and you spin the tires. Once that happens you can drive, but the pedal still seems stiff making acceleration jumpy. The throttle cable moves freely, although it has been broke right on the carb end and is about an inch short, so I built a metal extension that fits over the 1/4 inch carb stud and this all moves freely.

Other than possibly needing a new cable, what else could make the accelerator so stiff? My son turns 16 in Sept and he really does not need a car that burns the tires. Thanks.

[mikem 13]

Try disconnecting the accelerator cable at the carb and move the carb linkage by hand. Do you have a binding return spring or something else the carb linkage is catching on? Check the pedal side also to make sure there isnt something binding when you initially apply pedal. If the carb throttle moves freely by hand without binding and the same for the pedal, could you possibly have a bend in the accelerator cable that might be catching? I think i would replace that accelerator cable at any rate.

[mikem 13]

Try disconnecting the accelerator cable at the carb and move the carb linkage by hand. Do you have a binding return spring or something else the carb linkage is catching on? Check the pedal side also to make sure there isnt something binding when you initially apply pedal. If the carb throttle moves freely by hand without binding and the same for the pedal, could you possibly have a bend in the accelerator cable that might be catching? I think i would replace that accelerator cable at any rate.

[69RavenConv 286]

Agree with Mikem. I'd look for a defect in the cable first, then look at the gas pedal for bends or binding. Maybe watch the carb (engine off) while an assistant slowly depresses the gas pedal to see when and where it breaks loose. If nothing under the hood looks bad, do the same while watching the gas pedal. (Youngsters are better suited for that). Welcome to the forum, you watching Kansas in the NCAA?

[69RavenConv 286]

Agree with Mikem. I'd look for a defect in the cable first, then look at the gas pedal for bends or binding. Maybe watch the carb (engine off) while an assistant slowly depresses the gas pedal to see when and where it breaks loose. If nothing under the hood looks bad, do the same while watching the gas pedal. (Youngsters are better suited for that). Welcome to the forum, you watching Kansas in the NCAA?

[BRADVAN 10]

Thanks for the replies. The cable is going to be replaced, though as I said it moves freely,and we'll try the other suggestions this weekend. Couple more questions. To attach the cable to the carb, I bought a 1/4" stud that bolts to the carb, $4.95 type thing at the local suto store. Good enough? Also could the return spring be too stiff? It's really seems stiff, but I don't know how much pressure it is supposed to have? And yes KU is my team.

[BRADVAN 10]

Thanks for the replies. The cable is going to be replaced, though as I said it moves freely,and we'll try the other suggestions this weekend. Couple more questions. To attach the cable to the carb, I bought a 1/4" stud that bolts to the carb, $4.95 type thing at the local suto store. Good enough? Also could the return spring be too stiff? It's really seems stiff, but I don't know how much pressure it is supposed to have? And yes KU is my team.

[StephenC 10]

I had the same problem with mine not really a fix for I recommend getting a Lokar cable they look great and are the smoothest feeling cable I ever had on my 69

[StephenC 10]

I had the same problem with mine not really a fix for I recommend getting a Lokar cable they look great and are the smoothest feeling cable I ever had on my 69

[stangme428 33]

any special part number on the lokar cable? or order a generic?

 

I had the same problem with mine not really a fix for I recommend getting a Lokar cable they look great and are the smoothest feeling cable I ever had on my 69

[stangme428 33]

any special part number on the lokar cable? or order a generic?

 

I had the same problem with mine not really a fix for I recommend getting a Lokar cable they look great and are the smoothest feeling cable I ever had on my 69

[StephenC 10]

Heres the link for the cable http://www.jegs.com/i/Lokar/625/TCP-1000HT36/10002/-1

You will also need this http://www.jegs.com/i/Lokar/625/SRK-4000/10002/-1

Same exact one I have on my 69 fastback looks great.

[StephenC 10]

Heres the link for the cable http://www.jegs.com/i/Lokar/625/TCP-1000HT36/10002/-1

You will also need this http://www.jegs.com/i/Lokar/625/SRK-4000/10002/-1

Same exact one I have on my 69 fastback looks great.

[BRADVAN 10]

Original poster here. I'm back after a multitude of issues. Any way, the old throttle cabel worked freely, but due to how it was goobered together, I took the suggestions and bought and installed a new one. It moves very smothly, but the accelerator is still quite stiff. The carb linkage moves freely. I am now convinced the problem is the throttle-return-spring tension. Any ideas how much spring tension shoud be? Thanks.

[BRADVAN 10]

Original poster here. I'm back after a multitude of issues. Any way, the old throttle cabel worked freely, but due to how it was goobered together, I took the suggestions and bought and installed a new one. It moves very smothly, but the accelerator is still quite stiff. The carb linkage moves freely. I am now convinced the problem is the throttle-return-spring tension. Any ideas how much spring tension shoud be? Thanks.

[foothilltom 33]

Perhaps pictures of your throttle cable setup (coming out of the firewall, the angle at which it comes in to the carb, the bracket that holds it, and the attachment to the carb itself) would help. The geometry of the cable bending toward the carb could cause the stiffness you are describing.

 

Can you try the experiment mikem suggested? This mystery can be solved by removing variables in a controlled way.

 

And speaking of variables, it's unlikely, but perhaps the bushing in your throttle pedal is bad and causing it to hang up?

 

Good luck.

[foothilltom 33]

Perhaps pictures of your throttle cable setup (coming out of the firewall, the angle at which it comes in to the carb, the bracket that holds it, and the attachment to the carb itself) would help. The geometry of the cable bending toward the carb could cause the stiffness you are describing.

 

Can you try the experiment mikem suggested? This mystery can be solved by removing variables in a controlled way.

 

And speaking of variables, it's unlikely, but perhaps the bushing in your throttle pedal is bad and causing it to hang up?

 

Good luck.

[BRADVAN 10]

OK, when I disconnect the accelerator cable the carb linkage moves smoothly but the return spring seems way too tight/strong. When I remove the return spring the carb linkage moves/feels just like the brand new Edelbrock 1406 I put on my 65 fastback. With the accelerator cable removed from the carb the accelerator pedal moves freely without binding. As I posted earlier, I have purchased a new accelerator cable and it moves smoothly. If I knew how to post pictures I woould. Maybe my son can teach an old dog a new trick? Thanks.

[BRADVAN 10]

OK, when I disconnect the accelerator cable the carb linkage moves smoothly but the return spring seems way too tight/strong. When I remove the return spring the carb linkage moves/feels just like the brand new Edelbrock 1406 I put on my 65 fastback. With the accelerator cable removed from the carb the accelerator pedal moves freely without binding. As I posted earlier, I have purchased a new accelerator cable and it moves smoothly. If I knew how to post pictures I woould. Maybe my son can teach an old dog a new trick? Thanks.

[foothilltom 33]

Based on what you've described, the return spring is the next best suspect, but the "jerky" behavior you initially reported doesn't quite square with an overly energetic spring. You'd think it would just be consistently harder to open the throttle.

 

One way to find out...swap out a weaker spring! Best of luck.

 

Tom

[foothilltom 33]

Based on what you've described, the return spring is the next best suspect, but the "jerky" behavior you initially reported doesn't quite square with an overly energetic spring. You'd think it would just be consistently harder to open the throttle.

 

One way to find out...swap out a weaker spring! Best of luck.

 

Tom

[MikeStang 247]

Sounds like the VEnturi / carb butterflys in the carburetor may either be Dirty or slightly bent or distorted.........take the carb off....clean venturis ....just take some carb spray and spray in the venturi, and wipe em with a rag .....get it all nice and clean ....see if this frees them up some....had this happen and it produce the exact symptoms your talking about....Same things happen to throttle body chevys....you gotta kinda snap the throttle to make it open smooth and then it learches and away you go.......also try adjusting the idle up a little bit. if the blades are going into the venturis too far when you release the throttle......if the return spring is too heavy it can help contribute to SLAMMING the throttle blades into the venturi, thus causing a sticking symptom.....raise the idle and see what happens....I would do this first....carb may be way out of adjustment

Mike

[MikeStang 247]

Sounds like the VEnturi / carb butterflys in the carburetor may either be Dirty or slightly bent or distorted.........take the carb off....clean venturis ....just take some carb spray and spray in the venturi, and wipe em with a rag .....get it all nice and clean ....see if this frees them up some....had this happen and it produce the exact symptoms your talking about....Same things happen to throttle body chevys....you gotta kinda snap the throttle to make it open smooth and then it learches and away you go.......also try adjusting the idle up a little bit. if the blades are going into the venturis too far when you release the throttle......if the return spring is too heavy it can help contribute to SLAMMING the throttle blades into the venturi, thus causing a sticking symptom.....raise the idle and see what happens....I would do this first....carb may be way out of adjustment

Mike

[DRASTiK 22]

+1 to what Mike said above.

 

Also, since the individual pieces all seem fine when disconnected from one another, maybe it's related to the setup of the bracketry the cable is attached to putting a bind on something when everything's connected. As mentioned earlier, pics would be needed to see what you're working with if you're still having issues.