440 six pack help

[sixmanfan]

I have a 1970 440 six pack that i can't get to run like I want it too. It idles fine after the engine warms up {but not cold}. The engine seems to have a lope or surge {not sure what to call it at} when cruising. When you put your foot in it the engine runs fine. When you shift down it doesn't really have a big back fire but it has a crackle to it.
Any Ideas on what might be the problem. This is a new six pack that was just put on.

[ChallengerHK]

How were the carbs tuned? Have you checked for vacuum leaks?

[sixmanfan]

I can't answer how the carbs or tuned. i had a hot rod shop do the installation. {I knew that a six pack was hard to tune so I had it done by someone who I thought knew what they were doing.
 But have checked for vacuum leaks. bust didn't find anything.

[Jamiez]

There are mechanical six pack set ups too aren't there?  I guess finding out what you have would be a good first step

[Chryco Psycho]

the surge could be just in the dist , was it running before the 6 pack ?
 Do you know what the vacuum is at idle , in gear if Auto trans , the power valve may not be staying closed causing a surge.
 Timing could be over advanced as well , you want total of 36-38*

[VTMopar]

I don't want to hi-jack this thread - but mine needs tuning (and it is not something that I have the expertise to even try) - my local mechanic (who is very good) suggests installing this -- suggesting that it makes it significantly easier and allows for a much better tune-up.....   What do you guys think?   Is it worth it?   

Billet throttle base from ProMAx Performance:   Our billet Six Pack throttle base is designed so you can get to the idle mixture screws while the motor is running!   The new base has angled mixture screws for access, so you don't have to take the carb off anymore to adjust.  Base comes with new top and bottom gaskets.  Just transfer over your old throttle shaft and plates and you are ready to go! 
 

[Chryco Psycho]

looks like a great idea , you only need one base though for the rear carb

[VTMopar]

Thanks Chryco........ I was hoping you would respond......

[73Chally]

I had a similar problem and it turned out to be the float was set too high.  It would kind of "buck" when cruising between 30-40 mph, and would almost die when I down shifted approaching a stop sign.  Once the float was lowered a bit, it ran great.

[Chryco Psycho]

There really is nothing difficult about setting up a 6 pack ..... think of it as a 4 bbl carb everything is run off the center carb [primary] . All the idle , accelerator pump , choke settings as well as jetting for cruise , power valve for added power with low vacuum are controlled from the center carb , the outboards [secondary] barely come into play , all they have is an idle screw to assit the idle circuit . The Springs can be swapped to allow faster opening , you can use to different springs to blend to opening rate if they open too fast it will bog so often it needs to be slower  . There is no accelerator pumps to deal with , set the float levels & there is very little else to adjust . You can buy metering plates to go inside the outboard carbs to allow for jetting changes .
 This all applies to the stock vacuum secondary 6 pack systems , if youhave the race carbs then you do not need to buy anything to adjust jetting as they all have metering plates already & you have to deal with acceleraor pumps on all 3 carbs .

[Cuda Cody]

I will add this....  I just built a 383 and used a cam recommended by the machine shop, but the motor never ran "right".  Much like you I was chasing little things and not happy.  Changed cams to a Mr. Six Pakc cam and EVERYTHING was better.  I could not believe the difference a good cam can make. 

Was the motor running fine before the new carbs or is this a new build?

[Chryco Psycho]

Cam choice can make a huge difference . What cam did you remove Cody ?

[Cuda Cody]

I have the specs at home on the first cam, but I remember it wasn't real aggressive on paper.  112 grind with good vacuum.  It sounded real good in the car, but I couldn't get it to run right.  That might have been because I was using all stock stuff.  The cam really wanted more than the stock carb could give it.

Mr. Six Packs grind is so freaking awesome with stock components.!  The sounds good, runs like a new motor should and has WAY more seat of pants HP.  He doesn't give out his grind info, but I will look to him first now for all my cams.

Cam choice can make a huge difference . What cam did you remove Cody ?

[Chryco Psycho]

you can usually get there with stock carbs , but there is a lot of tricks to make that happen !!
 I am glad the 2nd cam worked better.
 How did you like the cam we picked for the SE years ago ??

[TinCuda]