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Dual Carbs and Stiff Gas Pedal

Posted By: Mopar_Mudder

Dual Carbs and Stiff Gas Pedal - 06/03/13 06:29 PM

This is my first time having dual carbs, have driven triples though. Any way I have a return spring on each carb and everything is nice and smooth when it isn't running.

But when it is running it take alot of pedal pressure to get the carbs off idle, this makes taking off nice and easy difficult. Once you get off idle it is smooth again. Seems like it is trying to break the suction of the engine trying to pull the plates shut or something. Never ran into this before, any ideas?

Posted By: 62maxwgn

Re: Dual Carbs and Stiff Gas Pedal - 06/03/13 06:43 PM

From what I see,you are opening both carbs at the same time,no problem here with factory linkage.

Attached picture 7729580-Picture081.jpg
Posted By: topside

Re: Dual Carbs and Stiff Gas Pedal - 06/03/13 06:44 PM

My Street Hemi - original carbs, intake, springs - takes noticeably more pedal pressure than say a stock 383 car, but I wouldn't say excessive. Same pressure running/driving as not. I can feel when each of the 4 stages open, which is common to every Street Hemi I've driven.
Only thing I can think of on yours is maybe some binding that's aggravated by heat - which would be odd - or your butterflies are somehow closing over-center - which I don't should be possible - or too tightly.
Posted By: Cab_Burge

Re: Dual Carbs and Stiff Gas Pedal - 06/03/13 06:50 PM

Put weaker springs on it or stretch the ones you have The last thing is to check both carbs for binding on the throttle linkage, also try looseing the fasteners on the carbs base plate a little, not real loose, just barely snug and try that from the driver seat If is better looser then you know what to work on
Posted By: mickm

Re: Dual Carbs and Stiff Gas Pedal - 06/03/13 06:59 PM

what cab said. it's easy to see in the picture that you have too much pressure on those springs. at idle, mine are barely extended, and i have roughly the same setup as you.
Posted By: Mopar_Mudder

Re: Dual Carbs and Stiff Gas Pedal - 06/03/13 07:09 PM

I will mess with the springs and see what I can do. Just odd how much difference their is from not running to running. It is not a heat issue because you can tell it right away when you start it up cold.
Posted By: 340SHORTY

Re: Dual Carbs and Stiff Gas Pedal - 06/03/13 07:15 PM

Raise the mounting point of your throttle cable. Some Mopars have a little 90 degree bracket that will raise it by about 3/4" to 1".
You need springs capable of closing the butterflys not barn doors..
Posted By: Mopar_Mudder

Re: Dual Carbs and Stiff Gas Pedal - 06/03/13 07:53 PM

They are the stock springs for a hemi, well reproduction so I don't know how close the pull it on them. But the carbs are not stock so I am guessing the arms are in a different place then stock creating more stretch on the spring.
Posted By: Anonymous

Re: Dual Carbs and Stiff Gas Pedal - 06/03/13 08:28 PM

I would temporarily remove just the green spring and see what happens. Problem might be the carb butterflies sticking, not too much spring pressure.
Posted By: mickm

Re: Dual Carbs and Stiff Gas Pedal - 06/03/13 08:56 PM

Quote:

I will mess with the springs and see what I can do. Just odd how much difference their is from not running to running. It is not a heat issue because you can tell it right away when you start it up cold.



i'm not sure what you mean by this, can you elaborate?

it looks to me like the angle that the throttle cable is at in relation to the position on the linkage is good. check it by going to WOT. the cable should be at roughly the same angle, i.e. the cable should not be at a different angle than what the clamped section in the bracket is.

it also looks like your setup is not progressive. with the stock manifold there is no reason that it shouldn't be, as far as i know.

i use the stock repop springs on mine, and they work well.
Posted By: JohnRR

Re: Dual Carbs and Stiff Gas Pedal - 06/03/13 09:04 PM

What the 2 guys above me said , you are pulling on 2 carbs at once . pull the spring off the front carb and see how much that lightens it up.Plus opening both carbs at once is not going to help the taking off easy part.

Are those carbs 650's or 800's ?
Posted By: Mopar_Mudder

Re: Dual Carbs and Stiff Gas Pedal - 06/03/13 09:11 PM

Quote:

What the 2 guys above me said , you are pulling on 2 carbs at once . pull the spring off the front carb and see how much that lightens it up.Plus opening both carbs at once is not going to help the taking off easy part.

Are those carbs 650's or 800's ?



They are 1406's which are 600cfm I believe?

They came set-up with a 1:1 ratio from the engine builder so I left it alone and didn't want to mess with retuning it for pregressive.
Posted By: Mopar_Mudder

Re: Dual Carbs and Stiff Gas Pedal - 06/03/13 09:14 PM

Quote:

Quote:

I will mess with the springs and see what I can do. Just odd how much difference their is from not running to running. It is not a heat issue because you can tell it right away when you start it up cold.



i'm not sure what you mean by this, can you elaborate?





When it is not running the trottle pedal is real easy to move and start opening the carbs. When it is running the force on the pedal is much greater to start opening the carbs. It is bizzar, maybe I am just lossing it

I will try removing a spring. Just like the idea of two springs, plus must race events require dual springs.
Posted By: JohnRR

Re: Dual Carbs and Stiff Gas Pedal - 06/03/13 09:16 PM

Interesting if they are 1406's , they have the Thunder AVS tops , 1406's are performer series carbs.

Is the intake stock or Vanke modded ?

Did you ask the builder why he set them up 1:1 ? is it stock cubes or a stroker ?
Posted By: Mopar_Mudder

Re: Dual Carbs and Stiff Gas Pedal - 06/03/13 09:21 PM

Quote:

Interesting if they are 1406's , they have the Thunder AVS tops , 1406's are performer series carbs.

Is the intake stock or Vanke modded ?

Did you ask the builder why he set them up 1:1 ? is it stock cubes or a stroker ?



It is a 472 with the Mopar #P5153737 intake. Now I am taking the carb based on what he sent me in an e-mail that he was going to use. I never actually looked for numbers on the carbs themselves.
Posted By: mickm

Re: Dual Carbs and Stiff Gas Pedal - 06/03/13 09:39 PM

something that may help right away. on the rear spring bracket, the throttle spring goes in the hole at the bottom of the bracket. the top hole is the spring for the kickdown linkage.

i think that will reduce the tension on that rear spring some.
Posted By: Mopar_Mudder

Re: Dual Carbs and Stiff Gas Pedal - 06/03/13 10:14 PM

Quote:

something that may help right away. on the rear spring bracket, the throttle spring goes in the hole at the bottom of the bracket. the top hole is the spring for the kickdown linkage.

i think that will reduce the tension on that rear spring some.



Yes it would, good catch on that, learned something new today

Also I know they are suppose to be swaped around. Green in front and Red in back, but it was way stiff when I did that, maybe using the lower hole I could.....will test. Yea I get to take all the Shaker stuff off again, man the guy who figured that mess out
Posted By: Anonymous

Re: Dual Carbs and Stiff Gas Pedal - 06/03/13 11:03 PM

Quote:

I will try removing a spring. Just like the idea of two springs, plus must race events require dual springs.



My suggestion was just to remove one of the springs temporarily to see if reducing spring tension solves your problem. Problem may be something else entirely. Not sure what, but maybe the linkage connecting the two carbs is sticking a bit from the vibration when the motor's running, but not when it's not. ?? I know it only took a tiny burr on the connector linkage on my Hemi to cause a problem.
Posted By: TooMany62s

Re: Dual Carbs and Stiff Gas Pedal - 06/04/13 01:02 AM

I think that linkage kit came with some brass bushings that allow you to move the mounting/pivot points up to the larger top holes. That's the way I have mine set-up and the pressure to operate doesn't seem excessive. It seems to work fine.
Posted By: Jack Zupan

Re: Dual Carbs and Stiff Gas Pedal - 06/04/13 01:07 AM

I had the same issue on mine. I have two springs and stretched the tightest one a bit. That seemed to take care of it.
Posted By: ProStDodge

Re: Dual Carbs and Stiff Gas Pedal - 06/04/13 06:39 AM

Quote:

Raise the mounting point of your throttle cable. Some Mopars have a little 90 degree bracket that will raise it by about 3/4" to 1".
You need springs capable of closing the butterflys not barn doors..



After looking at the photos, I would have to agree 100% with the above comment!
Posted By: Stanton

Re: Dual Carbs and Stiff Gas Pedal - 06/04/13 01:56 PM

Absolutely. The way it is now you're tugging almost directly against the throttle shaft. If your bracket were slightly lower you'd have bent the shaft by now !
Posted By: Mopar_Mudder

Re: Dual Carbs and Stiff Gas Pedal - 06/04/13 02:50 PM

I know what you are saying about the angle of the cable. If anything I would probably make a bushing to go under the existing bracket and raise is up. I hate to mess with the stock mounting locations too much, trying to keep it as stock appearing as possible.

On the mounting location of the linkage connecting the carbs are you saying to use the large hole above where it is mounted now? If so I don't know that I would have enough pedal travel to get full throttle then, would have to look into it.

Here is a better picture of the throttle cable. Didn't have time to mess with it last night, had T-Ball, maybe tonight.

Posted By: 62maxwgn

Re: Dual Carbs and Stiff Gas Pedal - 06/04/13 02:56 PM

If you look at the picture I posted with factory linkage,the linkage is connected to the upper part of the throttle shaft on the read carb,much less effort than where you have it,also compare the angle of the cable.
Posted By: Mopar_Mudder

Re: Dual Carbs and Stiff Gas Pedal - 06/04/13 02:59 PM

With out having an actually dimension is it hard to tell. The front carb looks like the linkage is way down low. On the back carb the linkage from front to back carb is up high but the cable looks lower.
Posted By: 62maxwgn

Re: Dual Carbs and Stiff Gas Pedal - 06/04/13 03:44 PM

Here is a picture of a set of 70 Hemi carbs,maybe you can compare linkage locations with the Edelbrocks.

Attached picture 7730559-P6040567.JPG
Posted By: Mopar_Mudder

Re: Dual Carbs and Stiff Gas Pedal - 06/06/13 03:15 PM

I did some messing with stuff last night and think I have found the problem. The rod ends on the linkage bewteen the two carbs is very tight. The balls do not move nice and free in the ends at all. Looks like a good system but not very smooth, gives a ratchety feeling when you try and open the carbs slowly. So I either need to find a way to loosen the balls up or just make my own linkage.

Oh I also found out what the carbs are, not what I was told originally they were going to be They are 1804 Thunber Series AVS 500cfm .
Posted By: JohnRR

Re: Dual Carbs and Stiff Gas Pedal - 06/06/13 03:26 PM

Quote:

I hate to mess with the stock mounting locations too much, trying to keep it as stock appearing as possible.





There is nothing even remotely STOCK APPEARING about the linkage between the 2 carbs. You can buy linkage that will work correctly and look a lot more stock appearing even with those carbs.

On the smaller carbs , the throttle response would be a little more crisp , but not sure how crisp with them opening together on that manifold ?
Posted By: Mopar_Mudder

Re: Dual Carbs and Stiff Gas Pedal - 06/06/13 03:33 PM

Quote:

Quote:

I hate to mess with the stock mounting locations too much, trying to keep it as stock appearing as possible.





There is nothing even remotely STOCK APPEARING about the linkage between the 2 carbs. You can buy linkage that will work correctly and look a lot more stock appearing even with those carbs.

On the smaller carbs , the throttle response would be a little more crisp , but not sure how crisp with them opening together on that manifold ?



I know the linkage is no where near stock, but it is what came on it so I just left it. With the shaker step up on top you can't see any of it. If anything I will just make my own linkage so connect them, if I can't get the one in it to loosen up.
Posted By: JohnRR

Re: Dual Carbs and Stiff Gas Pedal - 06/06/13 04:45 PM

Loosen the bolts up , I'm going to guess how the guy cobbled that setup together that he just used full length threaded bolts instead of a shouldered type bolt and tightened it all up.
Posted By: sixpackgut

Re: Dual Carbs and Stiff Gas Pedal - 06/06/13 04:57 PM

ITS THE ANGLE OF THE CABLE!
Posted By: Mopar_Mudder

Re: Dual Carbs and Stiff Gas Pedal - 06/06/13 05:00 PM

They are shoulder bolts, I made them myself on the lathe starting with a piece of 1/4" smooth rod, so I am the cobbler. Originaly yes they did come with an allen bolt, but you can't over tighten a rod end, it's just not possible.

The problem is not the bolts. It is the rod ends themselves. The ball is too tight in the nylon lining of the rod end. It is the way they are manufactured, made by Edelbrock.
Posted By: Mopar_Mudder

Re: Dual Carbs and Stiff Gas Pedal - 06/06/13 05:06 PM

Quote:

ITS THE ANGLE OF THE CABLE!



I raised up the cable last night just to try. It made no difference having the cable straight in line.
Posted By: Cab_Burge

Re: Dual Carbs and Stiff Gas Pedal - 06/06/13 05:28 PM

When your running one to one linkage the interconnecting linkages need to be at the same distance from the throttle shafts, not one higher than the other I've used the Eddy carbs and linkage like your suing and if you want one to one lower the linkage mounting hole on the back carb. to macth the front carb. If you want it to be progressive linkage then the back one needs to be higher than the front so the back carb.(primary carb.) can open some before the front carb. starts to open
Posted By: JohnRR

Re: Dual Carbs and Stiff Gas Pedal - 06/06/13 05:46 PM

Quote:

When your running one to one linkage the interconnecting linkages need to be at the same distance from the throttle shafts, not one higher than the other I've used the Eddy carbs and linkage like your suing and if you want one to one lower the linkage mounting hole on the back carb. to macth the front carb. If you want it to be progressive linkage then the back one needs to be higher than the front so the back carb.(primary carb.) can open some before the front carb. starts to open



With this is mind , if he moves the one down in the rear that will change the pull ratio , have the COBBLER in you , , eliminate that hokey 2 piece setup between the 2 carbs , that is more than likely what is causing some of the binding due to the downward angle of the 2 parts.

Keep in mind the 2 ball joints need to be in the same hole on the lever or one carb will open at a different rate than the other and cause binding.
Posted By: Mopar_Mudder

Re: Dual Carbs and Stiff Gas Pedal - 06/06/13 05:54 PM

Quote:

When your running one to one linkage the interconnecting linkages need to be at the same distance from the throttle shafts, not one higher than the other I've used the Eddy carbs and linkage like your suing and if you want one to one lower the linkage mounting hole on the back carb. to macth the front carb. If you want it to be progressive linkage then the back one needs to be higher than the front so the back carb.(primary carb.) can open some before the front carb. starts to open



They are both in the same mounting location. Picture might make it look like they are different.
Posted By: mickm

Re: Dual Carbs and Stiff Gas Pedal - 06/06/13 07:35 PM

that setup should work if adjusted correctly.

i have a repop stock linkage on mine, and it works well, and i like the fact that even though it is far from stock, it still looks more stock than not, if you know what i mean

i custom made all my linkage and brackets, as i run a stage V manifold, where the carbs are farther apart, and the bosses on the manifold where the brackets sit don't exist, all the bolts are the same length.

there really shouldn't be any issue getting that linkage working, (i had exactly the same thing on my car when i first bought it years ago), but if you want, i'll post pictures of my stuff.
Posted By: Mopar_Mudder

Re: Dual Carbs and Stiff Gas Pedal - 06/06/13 07:59 PM

Quote:

that setup should work if adjusted correctly.

i have a repop stock linkage on mine, and it works well, and i like the fact that even though it is far from stock, it still looks more stock than not, if you know what i mean

i custom made all my linkage and brackets, as i run a stage V manifold, where the carbs are farther apart, and the bosses on the manifold where the brackets sit don't exist, all the bolts are the same length.

there really shouldn't be any issue getting that linkage working, (i had exactly the same thing on my car when i first bought it years ago), but if you want, i'll post pictures of my stuff.



I know it will work and I am 99% sure that the only problem is the tight rod ends in the linkage, they are really hard to turn. I have tried putting a bolt in them and then hooking a drill to the bolt to spin them. Thought maybe they would wear in and loosen up, but not luck with that.
Posted By: a12superbee

Re: Dual Carbs and Stiff Gas Pedal - 06/07/13 09:27 AM

If the balls are riding in plastic you can try boiling them in water for a few minutes then pulling them out and spinning the ball.
Maybe you can reform the high spot that seems to be dragging.
Posted By: BB65Barracuda

Re: Dual Carbs and Stiff Gas Pedal - 06/07/13 02:26 PM

Those Springs are actually rather wimpy.
I don't think I would remove them and operate the peddle. It's a [Edited by Moparts - Family Friendly Site - Keep it clean] when your gas peddle sticks open at high rpm.
First I should mention Im using the correct Linkage on the Hemi but the edelbroke one should be fine also.
I Had a similar problem the other day with the Hemi Coronet.
I had some help from a buddy of mine the other day.
Try starting the car, get out of the seat and operate the cable with your hand and see if you have a smooth transition without using the gas peddle.
As goofy as it sounds it turned out the neighbor must have mashed the peddle hard as he climbed his fat behind out of the driver seat and bent the arm the comes of the peddle that connects to the cable and it was no longer lined up correctly.
Same issue you are having.
Like I said my car is an older B Body and I am not sure if the E body is the same but it is exactly what turned out to be my problem.
Hope this helps.
Posted By: Mopar_Mudder

Re: Dual Carbs and Stiff Gas Pedal - 06/07/13 02:31 PM

I worked on the rod ends last night. I actually put a bolt in the rod end ball that I could put in a drill to spin the ball around. Then I submerged it in water that I mixed some glass polishing compound with. Took a few minuted for each end but after enough spinning in the solution they finally loosened up to where they move freely.

The pedal does feel better now but it is hard to say until I can drive it, and I can't do that until it stops raining some day
Posted By: BB65Barracuda

Re: Dual Carbs and Stiff Gas Pedal - 06/08/13 10:01 PM

Still Raining?
Posted By: Mopar_Mudder

Re: Dual Carbs and Stiff Gas Pedal - 06/10/13 02:39 PM

It was actually nice Saturday. But I had to work until noon and then I had to make a trip to help put a new garage door in my sister's garage, so that about killed the entire day. Sunday, yep it rained all day long, didn't get lawn mowed or nothing I wanted to done

Nice today so far, but have T-Ball with my son after work. Suppose to rain tomarrow, Wednesday looks good though. I can't believe the crazy weather we are having this year, feels like April not June.
Posted By: Mopar_Mudder

Re: Dual Carbs and Stiff Gas Pedal - 06/14/13 06:54 PM

Got to go for a drive last night finally. Pedal feel is much improved now.
Posted By: mickm

Re: Dual Carbs and Stiff Gas Pedal - 06/14/13 07:05 PM

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