6 pak choice what do you have?

[davek]

So I have had the 6 pak with vacuum secoundary setup. I liked it and it responded good. No complaints at all. Now I bought this Bee and in the purchase was a 6 pak setup with mechanical outboards. Not installed yet. 1 of my friends says the mechanical setup has a better response. So which setup do you like. My Bee is a 4 spd car. Thanks Dave

 

[lewtot184]

you'll never know until you try them both. pics of the carbs would help.

 

[PurpleBeeper]

I've only run the vacuum secondary 6-pack..... but I have run a 650 double pumper 4-barrel on this same motor and it literally cut my gas mileage in half. I was getting 6mpg city & 8mpg highway with 3.55 gears with the 650 dp. Mechanical secondary six packs are TRIPLE pumpers.

Track-only car....sure, why not run the mechanical carbs. Daily driver or long-distance driving to car shows....no way. Just my opinion.

 

[GetX'd]

I run mine with the mechanical set up and it goes like a raped ape. Not a track car - although it easily could be. Just not my thing. I have deeper gears with 3.91s. My mileage Is best guess at around 5-6 mpg. I have the 440 stroked to a 494 with 555 HP. Love the set up but the mileage is killing me. I really should change the gears so it would be a better cruiser. It's got a 727 auto in it.

 

[rumblefish360]

What I know about the two set ups are the centers are different cfm wise. The mechanical is a 500 and the OE a 350.

I don’t see a reason why you can not get decent mileage out of it if it is well tuned.

 

[493 Mike]

I'm running with the vacuum actuated secondary's and it works great. I have billet metering blocks in all 3 carbs so I can use regular jets in all 3. Tuning takes some time but the results are great!
Mike

 

[davek]

wow 493 mike never seen someone paint their carbs. thanks for all the replies.

 

[WileE]

Back in the day, I ran mechanicals when I raced. Unless that's your purpose, vac' s are fine, which I have now.

 

[Bill Monk]

The mechanical progressive linkage carbs are an old direct connection setup and were more race oriented. Either setup will work but all things equal, if it's a street car, then the original vacuum outboards, race then mechanical would probably work better. No doubt you are going to get better mileage with the vacuum outboards

 

[lewtot184]

the center carbs on the vac and mech are the same size. throttle bores and venturi are the same for the rear carbs. the mech are easier to tune but I think properly set up vacs could give a little more mid-range torque. on top end one shouldn't make anymore power than the other. I've used them all at one time or the other; even corvette carbs.

 

[493 Mike]

wow 493 mike never seen someone paint their carbs. thanks for all the replies.

Powder coat. The original finish was removed by TOO long a dip in my carb cleaner. You learn by mistakes!
Mike

 

[lewtot184]

something I've always found amusing is that the mech crabs have nearly identical air flow with a larger venturi area than a 1050 dominator, but people would consider the 1050 too large a carb to run on the street. i'm not advocating 1050's just wondering what goes thru peoples minds.

 

[Bill Monk]

something I've always found amusing is that the mech crabs have nearly identical air flow with a larger venturi area than a 1050 dominator, but people would consider the 1050 too large a carb to run on the street. i'm not advocating 1050's just wondering what goes thru peoples minds.

Yeah, mechanical CRABS flow a lot of air LOL!

 

[Daves69]

wow 493 mike never seen someone paint their carbs. thanks for all the replies.

My 2300 carb on the boat is painted red (same as engine) from the factory.

 

[62MAX]

Original mechanical carbs for reference.

 

[rumblefish360]

Original mechanical carbs for reference.

Nice pictures

The mechanical progressive linkage carbs are an old direct connection setup and were more race oriented. Either setup will work but all things equal, if it's a street car, then the original vacuum outboards, race then mechanical would probably work better. No doubt you are going to get better mileage with the vacuum outboards

How would you get better mileage?
Cruise is on the primary or should be alone.

the center carbs on the vac and mech are the same size. throttle bores and venturi are the same for the rear carbs. the mech are easier to tune but I think properly set up vacs could give a little more mid-range torque. on top end one shouldn't make anymore power than the other. I've used them all at one time or the other; even corvette carbs.

Are you sure the centers are all the same size?
Also, how do you figure the vacuum will make more torque over the mechanical if the Venturi sizes are the same?

 

[Bill Monk]

Nice pictures

How would you get better mileage?
Cruise is on the primary or should be alone.


Are you sure the centers are all the same size?
Also, how do you figure the vacuum will make more torque over the mechanical if the Venturi sizes are the same?

The mechanical carbs have a progressive linkage, they will come on faster than the vacuum secondaries

 

[rumblefish360]

So, in other words, as long as I keep my foot out of it I’ll get the same mileage. Correct?

 

[Bill Monk]

So, in other words, as long as I keep my foot out of it I’ll get the same mileage. 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

 

[lewtot184]

Nice pictures

How would you get better mileage?
Cruise is on the primary or should be alone.


Are you sure the centers are all the same size?
Also, how do you figure the vacuum will make more torque over the mechanical if the Venturi sizes are the same?

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.