# Slow Acceleration After Edelbrock Carbuerator Installation



## shimelhoch (Dec 9, 2009)

*Slow Acceleration After Edelbrock Carburetor Installation*

Hello,

I installed and Edelbrock 1406 onto an Edelbrock 2156 intake on a 1969 Pontiac 350 V8 (Pontiac LeMans/Auto/Turbo 350). The engine starts and idles great. Transmission shift smoothly and engine runs smooth at low and high speeds. Problem is that acceleration is slow, even with the pedal to the metal.

Any thoughts on the correct order of trouble shooting?

Thank you,

Scott


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## 05GTO (Oct 6, 2004)

Sounds like a kickdown switch problem to me,


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## NorwalkNugget (Aug 5, 2011)

I'm no expert but I've been doing a ton of research as I plan to replace my Holley carb at some point.

I think you got to keep in mind the Edelbrock won't give you the same "punch" you may have had from previous carb... especially if it was a Holley. You may have to adjust the jetting on that carb to get the power your looking for.... Or a bigger carb... meaning one size up.


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## jetstang (Nov 5, 2008)

Keep tuning on it. Jet rods pull right out the top, get a trick kit and tune for your setup. I got the same issue with my car, I want to put a holley back on, I don't like Edelbrocks, but am running the same carb. Put a good holley on and see the dif, right out of the box tuning.


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## Instg8ter (Sep 28, 2010)

or two...., could be any or all of the above. What gear is in your rear end? Does it stumble when you accelerate quickly, rattle, or just accelerate slow? Did it run better with the previous carb? Did you check for vacuum leaks?...eliminate whats right and you'll be left with whats wrong. Eddy's don't like more than 5lbs fuel pressure, could also be low fuel pressure from old rubber lines bleeding air into the mix or bad pump/fuel sock clogged......lol aren't old cars fun!!!


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## shimelhoch (Dec 9, 2009)

Thanks for the comments so far.... A little more info on the symptoms:

*Car just accelerates slow but there are no issues with stumbling or rattling
*Car starts and idles better than it ever has
*Automatic Turbo 350 which shift smooth and reliably
*Power brakes work very well
*No vacuum leaks that I can tell
* Previous setup was the stock intake with a 2 barrel rochester carb (the carb was not the stock carb for the 69 Pontiac 350 but appears to be from 1974)


Any additional thoughts or suggestions are welcome! Thanks again everyone!


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## Eric Animal (Oct 28, 2007)

Not enough cam for a 4bbl carb?


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## ALKYGTO (Mar 29, 2010)

Sounds basic, but did you check that the carb throttle plates open all the way when the pedal is on the floor. Have someone depress the pedal in the car and look down the throttle bores to verify. I recommend doing this with the engine off of course.

True story. I had an old 65 Plymouth that I used to take to the strip. Ran consistent high 13's until one trip where it ran 14.3 -14.4 consistantly. Thought it could be weather, tune......did'nt check for full throttle until I got home that evening and sure enough, the carb was'nt opening all the way. Sometimes it's the simple things.


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## Instg8ter (Sep 28, 2010)

:agree trouble shooting 101, start with the simple, eliminate whats correct until you find whats wrong. I picked up a new eddy 750 from a guy cheep, found out why when i got it....tang was bent on the linkage and it was preventing the secondaries from opening fully. Carb problems suck.


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## SDGoat619 (Mar 21, 2011)

Any updates on this I am having trouble still with my 800 cfm eddy on my 455. Slow accelleration not snappy by any means. Thinking of trying different jet combo, also thinking of looking for a q-jet 

Sent from my PC36100 using AutoGuide.com App


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## NorwalkNugget (Aug 5, 2011)

Could also look into a torque converter upgrade... I know when I did that to my car it brought it to life.


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## SDGoat619 (Mar 21, 2011)

SDGoat619 said:


> Any updates on this I am having trouble still with my 800 cfm eddy on my 455. Slow accelleration not snappy by any means. Thinking of trying different jet combo, also thinking of looking for a q-jet
> 
> Sent from my PC36100 using AutoGuide.com App



Update: I got a chance to tinker today on my Eddy 800cfm and wanted to share some info as to what helped me to tune my 1412. First of all edelbrock tv on you tube is a good resource for tuning and according to the tech there are two vaccum ports on the front of the carb. Mine I installed on the left side and according to the tech the right vac port is the port you cant to use as it is better for vac on high performance motors. Made the switch and WOW much better. After that slight adjustment to fast idle srew and the air/fuel mixture screws and the 455 is now very responsive at the gas pedal. 

Apparently using the vac port on the left side of the carb didnt have enough vac to properly operate the metering rods action. 

Cant wait to road test it maybe next week


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## NorwalkNugget (Aug 5, 2011)

Congrats!

How involved was the install. Did you do it yourself? I'm looking to ditch my holley for an edelbrock unit but curious as to see what your thoughts are.


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## SDGoat619 (Mar 21, 2011)

I have never had a holly. I have only used edelbrock as that is what I have had laying around to use. I think that if you set up the carb to run with our combo all the carbs will run well and all have their advantages as well as disadvantages. However many will say when its all said and done nothing beats a properly gone through Q-jet. 

Sent from my PC36100 using AutoGuide.com App


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## shimelhoch (Dec 9, 2009)

Hello Norwalk, the install was not bad at all. I replaced the intake as well as the carb. Intstalling the intake and property sealing it to the water pump was probably the hardest part. The car runs very smooth, I am now just trying to get more power from the engine.


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