Need help tuning a six pack

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dartindanno

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Hey guys, this isn't for me but I have a buddy with a 71 Cuda, 440/six pack. He lives in Southeastern Wisconsin and cannot find anybody that can tune a car with a six pack. This has been an ongoing nightmare for at least a year and a half. Does anybody know of any shops or a guy that can properly tune those monsters?
 
If they are trying to tune it using the factory ignition specs... good luck.
 
Exactly! His 440 is built, big cam, aluminum heads. Doesn't seem to be anyone out there that can get the carbs working right.
 
I usually drink them one at a time until they are all empty and I'm getting tuned right in!!!!!! Sorry, had to go there!!!
 
It's no different than tuning a 4bbl Holley - but you need more parts and it's very likely that if tha carbs are not brandy new someone already messed with them internally...lol. Too bad you weren't closer. I'd love to tune that car :D
 
First step - make darn sure your ignition system is top notch. Many a night I spent trying to figure out what carb issues I had only to find out my ignition wasn't right.

There really is no difference between a four barrel and a sixpack. Make sure the float levels are set right and have no vacuum leaks.

You have to get the idle circuitry right first. You should be able to kill the engine by turning the center air fuel mixture screws in all the way or all the way out. This means your air fuel mixture at idle is in the ball park.

Most people don't know this about six-packs but the outboard carbs do have air/fuel mixture screws. They are located in the front of the base plate behind lead seals. The rear carb needs to be removed to set them. I set mine around a turn to a turn and a half (I think) and that got my idle circuitry in the ball park so that the center carb could be adjusted for the best idle.

After that, I used stock jetting with good results.

You might need to change the secondary springs to get the outboards to open at the right rpms.

Rod
 
Tune in the center carb before you start with the outboards.

They're not much harder than a 4 bbl Holley.

Think of them as a Holley 4 bbl with two sets of secondaries.... (Now that's a spreadbore....)


I'm in southwest burbs of Chicago. I'm a little familiar with Holleys.... I may be able to help a little.

PM me an email address, and I can give you a few tips.
 
The first and most important thing I've found on setting up a Six Pack is to make sure the outboard carburetor's butterflies have a super tight seal against the base plate. This is easy to check: With engine at idle, no air cleaner, put your hand over each carb, one at a time, as if to choke it, and see/feel if either is pulling vacuum.
If either carb is drawing in air you have a butterfly to base plate problem and you'll tear your hair out trying to adjust your primary carb. The only way I can put it is those outboard carbs should be turned off completely- as if they weren't there.
At that point you can set up your primary- with the outboard carb linkage temporarily disconnected. Now your setting up a two barrel- no problem. If your outboard carburetors still have the factory seal you shouldn't have to mess with them unless you have made major cam/compression ratio changes to your engine, then jet changes may be necessary. Basically your outboard carb's are either on or off; your driving around with a two barrel until you step into it. That being said, you can adjust your linkages to bring the secondary carbs in at an earlier RPM for serious thrashin'. Just remember; you will be using twice as much fuel, and if your riding around town like that you will be washing the cylinders with gasoline- Not good.
Hope that'll help you.
TPG
 
I guess I'd want to see pics of his setup
before I'd hazard a guess.
Stock or aftermarket setup?
Carb numbers would be a start.
Manifold vac at idle & rpm and altitude.

That's assuming all the rest of engine/ignition is sorted.
If its that jackedup, I'd install a dual plane and single carb
just to see if its not something else not right before
I would place blame on the sixpac.
He could block off the two outboard carbs
with plates and see what he has.
If it won't run right on a 2bbl at least hes narrowed
it down to one carb or something else.
 
That being said, you can adjust your linkages to bring the secondary carbs in at an earlier RPM for serious thrashin'. Just remember; you will be using twice as much fuel, and if your riding around town like that you will be washing the cylinders with gasoline- Not good.
Hope that'll help you.
TPG


I agree with what you said until you got here.

You cannot/should not open the secondaries with a linkage unless they have been converted to open mechanically and have had accelerator pumps installed on them.

If you want to open the secondaries sooner, you put lighter springs in them until you find the correct ones for what you are looking for. Make sure that you put the same springs in both outboard carbs. The outboard carbs on a six pack are vacuum operated.

Trying to open them mechanically with a linkage will induce a bog because you don't have accelerator pumps to cover up the lack of fuel lean condition when you open them mechanically. This is the most common problems with people trying to set up six packs.

The linkages are used to help them open up evenly together at the same time.
 
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