Single Carb or Dual Quads which is better?

[Power Surge]

I like the look of the 1x4 with the turkey pan, which is why I chose that for my car. It went a little against my grain of originality, since S/Cs came with 2x4s. But since S/Cs were leftover comp cars, and comp cars used 1x4, well that worked for me . I think the 1x4 with T-pan looks more period correct than the 2x4 does, but that's just my personal taste.

I have tuned plenty of cars with 2x4s, and as long as they are setup right, they run great. In particular, the throttle response from the dual 450 mechanical setup is unlike anything else.

[601HP]

I am a big fan of horsepower and torque, but that twin Paxton setup intimidates me. You'd have to drug me into a stupor to get me in that car as a passenger.

David

[patrickt]

Originally Posted by Power Surge

I like the look of the 1x4 with the turkey pan, which is why I chose that for my car.

Absolutely correct.

[Power Surge]

Originally Posted by 601HP

I am a big fan of horsepower and torque, but that twin Paxton setup intimidates me. You'd have to drug me into a stupor to get me in that car as a passenger.

David

Those old ball drive Paxtons were complete junk. They couldn't make squat for power. That's why two were needed on a 427, because I am sure shelby put one on and realized it didn't do crap.

They look cool as hell, but you could make just as much power with a nice hi-rise 12.5:1 NA motor.

[Power Surge]

Originally Posted by patrickt

Absolutely correct.

I went one step more and put the grate from the S&H around the K&N element. The flash makes the K&N oil show up in the pic, but in person you'd never know there was a K&N on there...

[Power Surge]

Originally Posted by olddog

I have read that in a Cobra, the 2x4 actually produces more hp. Not because of the carbs, but because you can get more air through two filters than one filter. Again this only applies to the Cobra due to under the hood space limitations.

On original cars, I believe the 2x4 air cleaners were actually each smaller than the single 1x4 cleaner. Together they may still have had more surface area, but it was not two 1x4 air cleaners.

[Naumoff]

Sal, Your rear view mirrors in the wrong place.

I have seen pictures of vintage full comp cars without the turkey pan.
I think a lot of mechanics threw them away. They look like a royal PIA.
I am collecting parts to do a full comp car and I think I will not get a turkey pan just because I have seen original ones without them. But to each there own.

[patrickt]

Originally Posted by Naumoff

I think a lot of mechanics through them away. They look like a royal PIA.

They are... unless you have the foresight to have them fabricated to be easily removable.

[RodKnock]

Originally Posted by patrickt

They are... unless you have the foresight to have them fabricated to be easily removable.

Excellent! How or who did that for you?

[Power Surge]

Originally Posted by Naumoff

Sal, Your rear view mirrors in the wrong place.

I know . But that's not easily changed. And at least it's the RIGHT mirror

[patrickt]

Originally Posted by RodKnock

Excellent! How or who did that for you?

That was handcrafted by Bob Putnam at ERA using an English wheel, ball peen hammer, meticulous measuring and hours upon hours of labor. Here are two shots of it. You'll note that the english "Terry Body Springs" are safety wired even though they never seem to vibrate loose.

[Excaliber]

I never thought about the Turkey pan being in the way of the carb, but now that I do, man what a hassle that would be! I've had a bunch of carbs on my ride and tinkered and tweaked them no end until I finally got a combination I liked. That T Pan would have drove me nuts while getting stuff dialed in.

[patrickt]

Originally Posted by Excaliber

I never thought about the Turkey pan being in the way of the carb, but now that I do, man what a hassle that would be! I've had a bunch of carbs on my ride and tinkered and tweaked them no end until I finally got a combination I liked. That T Pan would have drove me nuts while getting stuff dialed in.

I do my carb with a vacuum gauge. I believe it would be physically impossible for me to get my fat, stubby fingers around the vacuum fitting at the base of the carb without my T-pan being removable.

[SuperHart]

Not to get into a discussion about mechanical versus vacuum secondaries, but Shelby used vacuum secondary carbs for a good reason, the secondaries open as engine demand increases rather than being either closed or wide open with those extra pump shots of fuel to cover the flat spots which is a waste on the street. Of course, I talk about only Holley carbs. Sorry Edelbrock and Carter AFB lovers, those carbs just don't cut it on a Shelby Cobra. Using a pair of 600 cfm carbs on your 427 is still overkill. A 427 at 7000 RPM assuming 100% efficiency will only need 875 cfm of venturi area. I had a friend who used a pair of Holley #8007 390 cfm carbs on his 427, fiddled with the jets a little and loves them to death. Then again, he drives 100% on the street and never pushes the motor to the breaking point. In addition, when mounted on the intake and covered with the S&H air cleaners, they look identical to the 600s. One last point, if you choose to run dual Holleys, ALWAYS use the dual quad secondary diaphragm cover kit to equalize the secondary diaphragms.

[patrickt]

Originally Posted by SuperHart

Not to get into a discussion about mechanical versus vacuum secondaries...

There are many nay-sayers on this board, but the truth is that mechanical secondaries offer our cars no advantages whatsoever over a properly sized and tuned vacuum setup. When properly adjusted, vacuum secondaries get the nod every time.

[Excaliber]

I was running mechanical secondaries with a pair of 600 cfm 'center squirters', which are basically 'drag race' carbs, not even a power valve on them! I did like the 'instant kick' they provided when you mashed the gas (this assumes all the planet were lined up, the atmospheric conditions were perfect and Jupiter also aligned with Mars). When they were working man it was great (mpg was horrible, by the way). I swapped them out for vacuum secondaries, same size, smaller jets with a power valve. I DID feel the loss of 'kick' when you mashed the gas hard, BUT, 1/4 mile times were virtually the same (as measured to the hundredths of a second)! They were also more reliable, but then again, those center squirters were old and finicky on the best of days.

[Silverback51]

Originally Posted by Excaliber

I was running mechanical secondaries with a pair of 600 cfm 'center squirters', which are basically 'drag race' carbs, not even a power valve on them! I did like the 'instant kick' they provided when you mashed the gas (this assumes all the planet were lined up, the atmospheric conditions were perfect and Jupiter also aligned with Mars). When they were working man it was great (mpg was horrible, by the way). I swapped them out for vacuum secondaries, same size, smaller jets with a power valve. I DID feel the loss of 'kick' when you mashed the gas hard, BUT, 1/4 mile times were virtually the same (as measured to the hundredths of a second)! They were also more reliable, but then again, those center squirters were old and finicky on the best of days.

I have the 660 center squirters and love them. And personally I also prefer the mechanical secondaries. My foot controls when they open.

But as some have mentioned. They can be a pain in the butt to tune.

[patrickt]

Originally Posted by Excaliber

I swapped them out for vacuum secondaries, same size, smaller jets with a power valve. I DID feel the loss of 'kick' when you mashed the gas hard, BUT, 1/4 mile times were virtually the same...

The mechanicals were giving you a "bog and rally," which fooled you in to thinking you were accelerating faster than you really were. The vacuums were coming on evenly and efficiently -- the proof is always in the numbers, not in the seat of the pants.

[Excaliber]

"Bog and Rally", thats fairly accurate patrickt, describes it well. But every once in awhile (planet alignment) they would hit 'just right' and it was great!

[Michael C Henry]

I have inline dual fours on a Dove tunnel wedge intake manifold. I'm limited to the little trimmed down S&H aircleaners . I think that is my limiter. I need another hoodscoop to get taller elements up into the flow. I'm leaning towards a reversed scoop ,like cowl induction. If I had nothing ,I'd buy a single four intake manifold Like a new Edelbrock Victor set up for multi-port fuel injection and a large single four style air door. and a huge aircleaner.