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Dual Carbs and Stiff Gas Pedal #1446905
06/03/13 02:29 PM
06/03/13 02:29 PM
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Wisconsin
Mopar_Mudder Offline OP
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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?


Last edited by Mopar_Mudder; 06/03/13 02:35 PM.

1971 Hemi Cuda 2005 SRT-10 Regular Cab Flame Red. 12.771 @ 109.67<---TIME SLIP--Video
Re: Dual Carbs and Stiff Gas Pedal [Re: Mopar_Mudder] #1446906
06/03/13 02:43 PM
06/03/13 02:43 PM
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Blair County,PA
62maxwgn Offline
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From what I see,you are opening both carbs at the same time,no problem here with factory linkage.

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Re: Dual Carbs and Stiff Gas Pedal [Re: Mopar_Mudder] #1446907
06/03/13 02:44 PM
06/03/13 02:44 PM
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So Near, Yet So Far
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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.

Re: Dual Carbs and Stiff Gas Pedal [Re: Mopar_Mudder] #1446908
06/03/13 02:50 PM
06/03/13 02:50 PM
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Bend,OR USA
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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


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Dual Carbs and Stiff Gas Pedal [Re: Cab_Burge] #1446909
06/03/13 02:59 PM
06/03/13 02:59 PM
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California
mickm Offline
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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.

Re: Dual Carbs and Stiff Gas Pedal [Re: mickm] #1446910
06/03/13 03:09 PM
06/03/13 03:09 PM
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Wisconsin
Mopar_Mudder Offline OP
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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.


1971 Hemi Cuda 2005 SRT-10 Regular Cab Flame Red. 12.771 @ 109.67<---TIME SLIP--Video
Re: Dual Carbs and Stiff Gas Pedal [Re: mickm] #1446911
06/03/13 03:15 PM
06/03/13 03:15 PM
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Kent, Wa
340SHORTY Offline
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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..


I am truckless..
Re: Dual Carbs and Stiff Gas Pedal [Re: 340SHORTY] #1446912
06/03/13 03:53 PM
06/03/13 03:53 PM
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Wisconsin
Mopar_Mudder Offline OP
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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.


1971 Hemi Cuda 2005 SRT-10 Regular Cab Flame Red. 12.771 @ 109.67<---TIME SLIP--Video
Re: Dual Carbs and Stiff Gas Pedal [Re: Mopar_Mudder] #1446913
06/03/13 04:28 PM
06/03/13 04:28 PM

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

Re: Dual Carbs and Stiff Gas Pedal [Re: Mopar_Mudder] #1446914
06/03/13 04:56 PM
06/03/13 04:56 PM
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California
mickm Offline
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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.

Last edited by mickm; 06/03/13 04:57 PM.
Re: Dual Carbs and Stiff Gas Pedal [Re: mickm] #1446915
06/03/13 05:04 PM
06/03/13 05:04 PM
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U.S.S.A.
JohnRR Offline
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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 ?

Re: Dual Carbs and Stiff Gas Pedal [Re: JohnRR] #1446916
06/03/13 05:11 PM
06/03/13 05:11 PM
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Wisconsin
Mopar_Mudder Offline OP
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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.


1971 Hemi Cuda 2005 SRT-10 Regular Cab Flame Red. 12.771 @ 109.67<---TIME SLIP--Video
Re: Dual Carbs and Stiff Gas Pedal [Re: mickm] #1446917
06/03/13 05:14 PM
06/03/13 05:14 PM
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Wisconsin
Mopar_Mudder Offline OP
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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.


1971 Hemi Cuda 2005 SRT-10 Regular Cab Flame Red. 12.771 @ 109.67<---TIME SLIP--Video
Re: Dual Carbs and Stiff Gas Pedal [Re: Mopar_Mudder] #1446918
06/03/13 05:16 PM
06/03/13 05:16 PM
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JohnRR Offline
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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 ?

Re: Dual Carbs and Stiff Gas Pedal [Re: JohnRR] #1446919
06/03/13 05:21 PM
06/03/13 05:21 PM
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Wisconsin
Mopar_Mudder Offline OP
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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.


1971 Hemi Cuda 2005 SRT-10 Regular Cab Flame Red. 12.771 @ 109.67<---TIME SLIP--Video
Re: Dual Carbs and Stiff Gas Pedal [Re: 62maxwgn] #1446920
06/03/13 05:39 PM
06/03/13 05:39 PM
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California
mickm Offline
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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.

Re: Dual Carbs and Stiff Gas Pedal [Re: mickm] #1446921
06/03/13 06:14 PM
06/03/13 06:14 PM
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Wisconsin
Mopar_Mudder Offline OP
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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

Last edited by Mopar_Mudder; 06/03/13 06:29 PM.

1971 Hemi Cuda 2005 SRT-10 Regular Cab Flame Red. 12.771 @ 109.67<---TIME SLIP--Video
Re: Dual Carbs and Stiff Gas Pedal [Re: Mopar_Mudder] #1446922
06/03/13 07:03 PM
06/03/13 07:03 PM

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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.

Re: Dual Carbs and Stiff Gas Pedal [Re: Mopar_Mudder] #1446923
06/03/13 09:02 PM
06/03/13 09:02 PM
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Greer, SC
TooMany62s Offline
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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.

Re: Dual Carbs and Stiff Gas Pedal [Re: TooMany62s] #1446924
06/03/13 09:07 PM
06/03/13 09:07 PM
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PA
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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.

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