6 pak choice what do you have?

[68 HEMI GTS]

Mechanical outboards will flow a bit more than the vacuums. Easier to jet. Unfortunately they have preset idle metering using weep holes on the outboards vs the vacuum outboards having fuel adjustment. It Is easier to step up to a 500 cfm center with the mechanicals. Either set up your crusing on a very small center carb, should be a wash as far as that. You can slow the vacuum carbs down to suit what the motor will handle. Being a stick car the pumpers should be funner if the motor will handle them when you go WOT.

I have this pair I built for the roadrunner. I may put adjustable idle circuits in the outboards depending on how they act. Center is a 4412. I don’t expect them to be any faster than the vacuum carbs, just something different. Plus I plan on going back to a clutch in the near future.

 

[lewtot184]

the mechanical carbs were the "cure" for the slower opening rate of the '69 carbs. the '70-'71 had modifications that increased the opening rate. a guy has to just pick his poison. personally, if I had a complete set of mechanical carbs i'd just sell them to someone who wants them and use the money somewhere else in my car.

 

[62MAX]

Also,as for mileage keep in mind even though the amount of fuel is minuscule,all three have accelerator pumps.

 

[rumblefish360]

Also,as for mileage keep in mind even though the amount of fuel is minuscule,all three have accelerator pumps.

Another member said all the centers are the same. 350 cfm. You have a 500 cfm center, correct?

probably not, with the vacuum outboards, they only come in at WOT, the other set up comes on as you step on the peddle. The linkage brings in the outboards quicker. In other words, you are bringing them in at partial throttle as well

That would also be vacuum secondary spring dependent. And properly set up for the intended performance of the engine. Even if the mechanical secondaries open up sooner on getting on the Hwy. or passing, I submit the extra power uses more gas but will get the car where it needs to be sooner saving gas.

If the outboard carbs are opening partially on cruise, something is off balance. should you not be cruising on the primary alone? It would seem stupid otherwise IMO.

Truly gas mileage between the two set ups is right foot controlled and not if it is vacuum or mechanical in operation.

I've had both vacs and mech. throttle bores and venturi are identical. the vacs will expose the engine to venturi area in a more controlled manner maintaining air velocity. velocity is torque.

While velocity is torque, so ids feeding the engine more air and fuel. IF the engine likes it.


Sorry gents, this is hair splitting and engine combo dependent. Your all wrong as well as right. The blanket statements are blanket statements.

 

[lewtot184]

i'm very comfortable in my wrongness.

 

[rumblefish360]

https://www.forabodiesonly.com/mopa...-6bbl-carburetor-4782.370095/#post-1971531379

https://www.forabodiesonly.com/mopa...-6bbl-carburetor-4782.368078/#post-1971500752

 

[68 HEMI GTS]

https://www.forabodiesonly.com/mopa...-6bbl-carburetor-4782.370095/#post-1971531379

https://www.forabodiesonly.com/mopa...-6bbl-carburetor-4782.368078/#post-1971500752

View attachment 585957

4782 stock center for the mechanical set up is a small 350cfm type carb. I have one from my set, I’ll snap a picture later. Nothing special.

My dad started converting 4412 (500 cfm) 2 barrels years ago for the vacuum centers. That’s what I run on my vacuum set up, I used the same main body and just swapped parts to try it with my mechanicals.

 

[62MAX]

Another member said all the centers are the same. 350 cfm. You have a 500 cfm center, correct?

That would also be vacuum secondary spring dependent. And properly set up for the intended performance of the engine. Even if the mechanical secondaries open up sooner on getting on the Hwy. or passing, I submit the extra power uses more gas but will get the car where it needs to be sooner saving gas.

If the outboard carbs are opening partially on cruise, something is off balance. should you not be cruising on the primary alone? It would seem stupid otherwise IMO.

Truly gas mileage between the two set ups is right foot controlled and not if it is vacuum or mechanical in operation.


While velocity is torque, so ids feeding the engine more air and fuel. IF the engine likes it.


Sorry gents, this is hair splitting and engine combo dependent. Your all wrong as well as right. The blanket statements are blanket statements.

Another member said all the centers are the same. 350 cfm. You have a 500 cfm center, correct?

All the centers are 350 cfm,Holley made a 500 cfm carb for many applications but not the Direct Connection set.Here is a set I'm trying to salvage with the correct bases and messed up linkage.

 

[POMONAMISSEL]

the all mechanical types are fords 406 . note the fuel entree is on the ford fuel pump side of the engine . i've run the set up before . on a 383 , would let the motor rev up there and pull hard . but those are gone . this package is on a rb in a hotrod driver p/u . still building on it . i have another 440 6pck in a challenger r/t . that motor sings to 8k . carrillo rods keep it together . and i have a few more in the wings . i like that set up alot , lol .

 

[493 Mike]

One other point to remember: Holley flowed 2 Bbl. carbs at a different vacuum to establish CFM than they used to rate 4 Bbl. carbs. Gotta wonder why.
Mike

 

[68 HEMI GTS]

4782 base vs 4412

4782 Venturi

 

[rumblefish360]

Now that right there is interesting for sure.

 

[lewtot184]

One other point to remember: Holley flowed 2 Bbl. carbs at a different vacuum to establish CFM than they used to rate 4 Bbl. carbs. Gotta wonder why.
Mike

marketing. 1350 is a cuter number than 1030. the originals were flowed at 1.5", not 3".

 

[lewtot184]

the original 401hp 390 and 405hp 406 three carb set-ups were called 6bbl. I always thought 6bbl was a mopar thing but ford used that term first.

 

[davek]

thanks for the schooling,never to old to learn.

 

[brian6pac]

I'm just finishing a set for a guy in Hawaii 7448 350 center and 4412 outer's

 

[davek]

this is what I got with the car was told intake and carbs are correct date for 1970

 

[davek]

on the charger I had the fuel line was on the passenger side-vac setup-why is the mechanical on the driver side?

 

[brian6pac]

on the charger I had the fuel line was on the passenger side-vac setup-why is the mechanical on the driver side?

Side pivot floats on drivers side, center pivot floats could be on ether side, Mopar right side, Chevy left side.

 

[Bill Monk]

i'm very comfortable in my wrongness.

as am I