Stiff gas pedal on 74 road runner (why are there two springs on carb?)

[tonyp25]

My gas pedal is quite stiff. I took a few pictures of my setup below. I can’t see anything suspect near the pedal itself but I did notice there’s two springs on the carb (only one of which has a dedicated hole to go into) creating some solid resistance. I swear the previous cars I’ve had only had one spring.

Is there a reason for the two springs or a specific one I can do without? Or possibly different springs in general.

I’m doing my best to become familiar with carbuerated cars (this is only my 3rd one and really the 1st I’ve heavily worked on). Looking to clean it and possibly rebuild with new gaskets soon but trying to figure this out first.

Really appreciate all the knowledge and advice you’ve all passed onto me this past week.

 

[Islandkent]

Did you check your cable by it self? Smooth operation? Unhook at the carb and see what it feels like? Check the carb linkage/ action while the springs are unhooked. Most guys run one spring. But if the do run two they usually run a smaller one inside a bigger one. Yes looks like lots of pressure to push that one to the floor. Certainly not factory springs there. Like I said check to see if anything is holding the return action back.

Another thing to remember to keep in your head. If your carb linkage does hang up/ wont return to idle. Shut the ignition off. Had it happen to me when I was kid took me about three seconds to come to my witts and shut off car and throw it in neutral. Lots can happen in three seconds. Go safe

 

[multimopes]

I only have one spring! i I suppose I should get a second one for reasons specified in this thread.

 

[halfafish]

In my area, if you take your car to the track the basic tech requirement is two springs. If it's not a stiff pedal, cable, or throttle plate you can replace the springs. Any auto parts store should have a spring kit. You can swap springs till you're happy. I'd still run two, even if they were light ones.

 

[DeltaV]

Really appreciate all the knowledge and advice you’ve all passed onto me this past week.

In general, another aid is a Factory Service Manual

You can get a used one from eBay for around $25 or an official reprint for around $60. It is probably available on CD-ROM, or some type of digital format too.

Also, a Parts Catalog is a handy reference. The authorized reproduction catalog I bought for my '70 Charger is very good and the diagrams/pictures are sharp and clear with good contrast.

Illustrated MoPar Parts Manual 1974 Plymouth - Dodge - Chrysler - Imperial

 

[DeltaV]

My gas pedal is quite stiff. I took a few pictures of my setup below. I can’t see anything suspect near the pedal itself but I did notice there’s two springs on the carb (only one of which has a dedicated hole to go into) creating some solid resistance. I swear the previous cars I’ve had only had one spring.

Is there a reason for the two springs or a specific one I can do without? Or possibly different springs in general.

I’m doing my best to become familiar with carbuerated cars (this is only my 3rd one and really the 1st I’ve heavily worked on). Looking to clean it and possibly rebuild with new gaskets soon but trying to figure this out first.

Really appreciate all the knowledge and advice you’ve all passed onto me this past week.

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Don't mess with the transmission kickdown linkage while you're troubleshooting the stiff pedal.

 

[toolmanmike]

My gas pedal is quite stiff. I took a few pictures of my setup below. I can’t see anything suspect near the pedal itself but I did notice there’s two springs on the carb (only one of which has a dedicated hole to go into) creating some solid resistance. I swear the previous cars I’ve had only had one spring.

Is there a reason for the two springs or a specific one I can do without? Or possibly different springs in general.

I’m doing my best to become familiar with carbuerated cars (this is only my 3rd one and really the 1st I’ve heavily worked on). Looking to clean it and possibly rebuild with new gaskets soon but trying to figure this out first.

Really appreciate all the knowledge and advice you’ve all passed onto me this past week.

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Boy, that's all F**ked up

 

[hunt2elk]

Go to Mega Parts or somewhere like it and get the correct spring and bracket.

 

[DeltaV]

My gas pedal is quite stiff. I took a few pictures of my setup below. I can’t see anything suspect near the pedal itself but I did notice there’s two springs on the carb (only one of which has a dedicated hole to go into) creating some solid resistance. I swear the previous cars I’ve had only had one spring.

Is there a reason for the two springs or a specific one I can do without? Or possibly different springs in general.

I’m doing my best to become familiar with carbuerated cars (this is only my 3rd one and really the 1st I’ve heavily worked on). Looking to clean it and possibly rebuild with new gaskets soon but trying to figure this out first.

Really appreciate all the knowledge and advice you’ve all passed onto me this past week.

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Your car started life as a 318-2V and now has a 4 barrel carb. That isn't an unusual upgrade.

4 Barrel Conversion: Necessary Brackets and Linkages?

 

[WileE]

It's a good thing to be stiff. Now, about your pedal. Dual carb springs is a GOOD idea. I know, 50 years ago when my only spring sprung. Just use a lighter, thinner spring inside your main spring.

 

[mrmolding]

Did you check your cable by it self? Smooth operation? Unhook at the carb and see what it feels like? Check the carb linkage/ action while the springs are unhooked. Most guys run one spring. But if the do run two they usually run a smaller one inside a bigger one. Yes looks like lots of pressure to push that one to the floor. Certainly not factory springs there. Like I said check to see if anything is holding the return action back.

Another thing to remember to keep in your head. If your carb linkage does hang up/ wont return to idle. Shut the ignition off. Had it happen to me when I was kid took me about three seconds to come to my witts and shut off car and throw it in neutral. Lots can happen in three seconds. Go safe

I wanted to reply after your post. I was 19 and it was very cold and my spring popped off/broke off during acceleration. The car hit an ice patch, kept accelerating and took off up a curb and into a tree, then bounced around and hit another tree in the right rear quarter. I did not come to my wits and totaled my prized 340 Dart. If I'd had two springs, nothing would have happened. What's funny is I sold it totaled to a collector for more than I paid for it.
I just bought a two spring concentric set from Ehrenberg on the bay. Each mopar since my 340 Dart gets two springs.

 

[Islandkent]

Like I said. Lots can happen in a few seconds. Always keep in mind they have a off-on switch. Use it if need be. See we're not the only ones to have crap like that happen. People get in trouble in split seconds.

 

[Black_Sheep]

IMHO your springs are stretched way too tight which will make the throttle pedal seem stiff and cause premature wear to the throttle shaft bushings. The coils should be almost touching with the throttle arm in the idle position. The wire diameter looks a little heavy too. I would start over with a couple “universal” springs that you can cut to fit.

Not the best picture, but you can zoom in and see what I’m talking about…

 

[toolmanmike]

IMHO your springs are stretched way too tight which will make the throttle pedal seem stiff and cause premature wear to the throttle shaft bushings. The coils should be almost touching with the throttle arm in the idle position. The wire diameter looks a little heavy too. I would start over with a couple “universal” springs that you can cut to fit.

Not the best picture, but you can zoom in and see what I’m talking about…

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THis ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Put a double spring on if you choose but get the right length springs so they aren't stretched so tight.

 

[Rishi]

If you need more or less pressure, I don't recommend modifying the spring.

On two different occasions, years apart, I was in a vehicle where the throttle return spring failed. In both of those cases, the owner had modified a single spring. In both cases, the failure point was the end hook where the owner had used needle nose pliers to alter its length. The springs failed at or near those bending points.

Whether you run one spring or two, swap in/out firmer or softer springs to your preference for foot pressure. But make sure the spring is sufficient for throttle closure.

A fresh spring, that hasn't been subject to fatigue by bending, will normally serve its function for decades before failure.

As others have said, disconnect the springs and confirm the throttle cable moves freely in and out without binding, and the carburetor butterflies open and close smoothly.

Be careful over-stretching a spring, because the resulting fatigue on the spring may cause premature failure.

For automatic transmission cars, yea, don't mess with the throttle pressure spring at the rear of the assembly.

 

[1967coronet]

Like posted above, use 2 springs but get some the correct length and a little smaller gauge.
Looking at the pics, check your throttle cable at the manifold end. That cable housing may be mashed under the retain clamp causing part of the problem.

 

[mrmolding]

Figured I'd share. I got this set in the link below, like in the engine pic above. Got my current 70 RR with one spring and the accelerator would not return completely -- the car would just go on its own with one spring. A little tighter with two but feels correct! Just realized it said out of stock! Hmm...anyway, I'm sure others have something similar.

ForMopar OEM-spec THROTTLE RETURN SPRINGS Small/Big-Block Plymouth Dodge A/B/C/E | eBay

 

[tonyp25]

If you need more or less pressure, I don't recommend modifying the spring.

On two different occasions, years apart, I was in a vehicle where the throttle return spring failed. In both of those cases, the owner had modified a single spring. In both cases, the failure point was the end hook where the owner had used needle nose pliers to alter its length. The springs failed at or near those bending points.

Whether you run one spring or two, swap in/out firmer or softer springs to your preference for foot pressure. But make sure the spring is sufficient for throttle closure.

A fresh spring, that hasn't been subject to fatigue by bending, will normally serve its function for decades before failure.

As others have said, disconnect the springs and confirm the throttle cable moves freely in and out without binding, and the carburetor butterflies open and close smoothly.

Be careful over-stretching a spring, because the resulting fatigue on the spring may cause premature failure.

For automatic transmission cars, yea, don't mess with the throttle pressure spring at the rear of the assembly.

Thanks for the info (and to everyone else who replied)! Disconnected the springs and the pedal moved great. Put just one spring back on and it was a normal amount of pressure. I’m buying a few new sets of springs and I’m going to try and get two on with the right pressure.

I know you mentioned not touching the rear throttle pressure spring (and maybe the picture below isn’t what you were referring to) but it seem precariously attached in the front (circled in yellow). So I really shouldn’t pull it about 1/2 inch forward so it can be on the same bolt the throttle return springs are on? Just seems like it could easily come off.

 

[tonyp25]

Like posted above, use 2 springs but get some the correct length and a little smaller gauge.
Looking at the pics, check your throttle cable at the manifold end. That cable housing may be mashed under the retain clamp causing part of the problem.

So after taking the two springs off it works great. Clearly just need a couple good set of springs that are the right size and gauge. I did notice the cable house seems to be deteriorating leaving just the metal thread exposed. Would you wrap that with some electrical tape?

 

[tonyp25]

Figured I'd share. I got this set in the link below, like in the engine pic above. Got my current 70 RR with one spring and the accelerator would not return completely -- the car would just go on its own with one spring. A little tighter with two but feels correct! Just realized it said out of stock! Hmm...anyway, I'm sure others have something similar.

ForMopar OEM-spec THROTTLE RETURN SPRINGS Small/Big-Block Plymouth Dodge A/B/C/E | eBay

Those do look perfect! Thank you. I shot the guy a message to see if he has anything similar or if he plans to get them in stock again