Superbird 6 pac question

[DoubleDlover]

So what is the big difference between the front and rear carbs on a 6 pac for a 70 bird??? I have a set up and just noticed both my front and rear carbs have the same part number and list number.... But in the book they list the front and rear carbs with different numbers... Soo whats the story?? ron

[hemi68charger]

Good question. I have been messing around with a six pack on my cars since '85 and never knew of a difference. The only thing I can think of is the preset positions of the base plate fuel/air metering screws that are plugged from the factory ( both front and rears are pre-set then plugged ).

[DoubleDlover]

Mine were rebuild so those plugs covering those mixture screws are off now. I can see both sets. If I run them would it work just fine? But if theres a difference somehow I hope to find out here. ron

[Ghoste]

A good question for Bob Karakashian maybe?

[RealWing]

Only difference in looking at the specs is that the front and rear are jetted slightly differently (via the secondary metering plate) Other than that, they appear to be identical

[pettybird]

why would they be jetted differently?  that makes no sense (not saying that you're wrong, just that I can't work out why it would be that way)

[A12 Superbee]

I think front and rear are identical, on A12 they are anyway.

[DoubleDlover]

yes that's what has me confussed.  even on my Pontiac tri powers the front and rear are the same. They work together. So this has be baffled...

[hemi68charger]

yes that's what has me confussed.  even on my Pontiac tri powers the front and rear are the same. They work together. So this has be baffled...

Does the Pontiac outboard carbs have idle circuits like the Chyrsler versions do? Since the Mopar six pack intake is of a dual plane design, maybe the rear runners need to have a different setting than the front. The Chrysler outboard carbs do have an idle circuit and are used all the time, albeit not to the extent of the center carb........ Just guessing from a mechanical-point-of-view,

[maxwellwedge]

Front and rear are different on every factory six pack setup. Every year...A12 included. Probably due to the fuel distribution requirements - front and rear on the dual plane intake.

I think the front and rear are identical on a lot of the aftermarket sets.....and probably the early over the counter carbs. Check the dates and see if they are originals.

Either way - they will work fine......it's just not correct if you are a purist.

[DoubleDlover]

hi. no. The Pontiacs don't have idle mixture screws on the outboard carbs. But the mopars do.  well if they will work ok. How about this. what should I set those outboard mixture screws at? r

[62 Max]

A place to start is about 1/8 turn out,they are very critical to adjustment.As for the plates the different jetting is keep air/fuel ratio basically the same due to intake runner design,69 1/2 carbs use a # 6178 plate in the front and a # 6180 in the rear,the 70 carbs use a # 34 front and a # 35 rear,69 anr 70 plates are not interchangeable.

Attached is the easiest way to adjust,when you have no change in idle with or without the air bleeds covered,idle mixture will be correct.

[62 Max]

I think front and rear are identical, on A12 they are anyway.

Actually they are not .