Single or dual quad 427 s/o?

[Flygirl]

I've driven a couple of 427 side oiler equipped cobras now, as well as a 392 Windsor.

The 392 had a throttle body injection system which seemed to run well but didn't look that good to me.

Both 427s had a single 4bbl carb, and both ran remarkably well on the street.

Now I'm thinking, I wonder how streetable a dual quad setup would be. I imagine vacuum secondaries and a progressive throttle linkage would be the way to go. I happen to be checking out another car with dual quads atop a single plane "tunnel wedge" intake, with the individual runners connected by a plenum.

I've heard these can run really well from idle to redline if set up correctly. And dang, the dual quads look reeeallly good.

Any thoughts about the dual quad setup for street use? Am I getting in over my head? Or just another case of paralysis by analysis?

[fordracing65]

Just get FI and be done with it.

[Jeff Frigo]

Unless you want the looks, the single four barrel will be just as strong (within 10 hp or so).

[blykins]

How good are you at tuning?

A pair of carbs can really test a tuner's patience, not to mention someone who hasn't messed with them before.

If I were to recommend a dual carb setup, it would be on a fairly streetable engine, with a mild cam and a dual plane intake. Trying to tune on an engine with say a Tunnel Wedge and a wild cam with lots of reversion will make you pull your hair out.

As the others have said, a good performing single carb intake will make just as much horsepower.

[Flygirl]

Thanks guys, you're confirming what I suspected. I'll be the first to admit I've never messed with a dual carb setup, for the reasons y'all are mentioning. Combine that with no hands-on FE experience, and I'm thinking that a single carb is the way to go for me.

—Natalie

[RICK LAKE]

Flygirl Natalie What are you looking for? A super cool look when you pop the hood? Something that no one else runs? Or just simple function? Manifolds and carbs come in different designs. Single carb single manifold, dual carb inline manifold, dual carb crossram manifold, ( one of my favorates) This is the same manifold as on the 200 mph Cosby cobra without blowers. It doesn't make the best power and tuning is ok but not great. Weber carbs and 4, 2barrels, what a look and work to get running well. Big price but TOO COOL to look at. Power wise, depending on motor a 10-30 torque and HP increase over any carb or carbs. If you have about 7g a set of 58MM webers will leave them with dropped jaws. The easiest is a single carb and manifold that has been ported to even up the Air/Gas flow to all 8 cylinders. I built a FI system 14 years ago for my car. Have not had a problem with it. IMO carbs are original and look great but other systems all need more work and time to get them to run right "everyday". IF you put a Large air cleaner assembly on the carb or carbs, you can't see them to well. I would say to have the intake manifold flow checked and ported to help the motor run better and pickup a couple of extra HP's. Rick L. Ps weather it's 1 carb or 8, it's the equipment for checking and testing for having the carbs work at there best. An A/F exhaust meter is a great place to start and vacuum gauge. If running a weber get an air flow meter that sit in the opening. When motors run right there is a sound they make that sounds like music. You will learn this with time and tuning. I heard a 482 motor and a set of 58MM OLbergs at a Run&gun in 01, there is nothing like it when they clear out and sync with the motor. It is one of the fastest street car without poweradders and under 12.0 compression. Have a nice day.

[Flygirl]

I'd like to be able to pop the hood and see the 427 logo on the pentroof rocker covers that matches the one on the outside of the car, and when I'm driving know it's a real side oiler. Why I can't tell you, it's kind of an emotional reaction.

Makes no sense in a way, a newer replica Cobra with a 45 year old engine.

But since the hood will (we hope) be closed most of the time, idling in traffic and not overheating and being reasonably tractable at lower speeds is important. A nice lumpy idle but nothing too extreme. A 427 s/o in that little car is extreme enough for me, even in lower powered (relatively) street tune.

Sometimes I wonder if I'm asking too much.

[patrickt]

It's pretty tough to wrap a Turkey Pan around dual carbs. Personally, that's one of my favorite looks to these cars -- you don't see it anywhere else. That's the main reason I went with a single. Plus, it's ridiculously easy to tune my single Holley four barrel and the center hung floats are an advantage in the corners (that's at the bottom of the importance scale to me, but to others it can be at the top).

EDIT -- btw, I'm told that the Turkey Pan increases steetability by helping to prevent the heat soak percolation in the carb from the heat. I don't know that to be a fact, though.

[elmariachi]

My engine dyno'd at 452 HP with a single 750cfm Demon. I was never happy with it, probably due in part to being at sea level and burning this crappy coastal gas. I messed with a couple of other 4-barrels but didn't have much luck. I scored an original 2x4 intake and found correct carbs and linkage. Bolted it all on, started it and have never looked back. My car runs much stronger and I feel like I am getting all the available power. It starts quick when cold, restarts easily when hot and who knows why, but while dozens in our club have suffered from issues from high ethanol, I have not had one problem in 4k miles.

You could buy the car with the 2x4s and if it doesn't suit you, trade down. Single 4 intakes and carbs are everywhere. Regardless, unless someone has had DIRECT experience with 2x4, their opinion here is just that.

Jim

[Dennis Mosley]

I couldn't agree with Jim more.

On my first cobra, I had a 428 FE and went through a number of different intake set ups, 2x4, 6x2 and stack FI system. Of them all I think the 6x2 was the most unique but not the best performer, the stack system was awesome looking but the 2x4 was just old school like the car and ran great. I never got really good at tuning the stack system but it ran nicely as well.

My current cobra has a 427 S/O with a 2x4 set up. LOVE IT!!!! Car is super strong and starts with the slight touch of the push button start. I won't be changing this intake system anytime soon....although I might be tempted if I found another 6x2 system....but that would just be crazy I do still have that 428 in the garage...hummmm.

[FUNFER2]

Jim- do you think the original 2x4 intake made the difference or the correct carbs ? What carbs are they ?

[elmariachi]

Originally Posted by FUNFER2

Jim- do you think the original 2x4 intake made the difference or the correct carbs ? What carbs are they ?

Kevin, that's a great question. I am sure naysayers will say the performance increase was because the 4-barrels I had tried were tuned all wrong but I even had Keith Craft's guys dyno tune a Holley 3255-1 LeMans and the 2x4s were a vast improvement over it.

I bought a set of original BC/BDs, list 3300 and 3301 that had been restored/rebuilt. I literally took them apart to notate jets and PVs, bolted them back together and slapped the whole assembly on. I came back after an initial weekend of running, reset the float levels and decreased primary jet size to 66 from 68 and that's been all I have done.

The MR intake seems to sit a tad tale than the Sidewinder, which probably helps and having a package of carbs and intake that were factory tested and matched must count for something. For what its worth, about the highest vacuum reading I could ever get on the Sidewinder was about 6.5" Hg. I even changed intake gaskets to be sure, still no change. On this intake I am getting 9" Hg at idle.

I have not yet had the car on a chassis dyno but I plan to this winter. If nothing gets any better I am a happy camper.

[patrickt]

If you do end up going the Turkey Pan route, make sure you have one fabbed that is easily removable. If you have large hands (no offense), it is a real nuisance to do anything with a carb in a Turkey Pan. I had mine custom fabbed to be removable, and that's going on six years ago. Since then a couple of folks on here now provide "removable Turkey Pans" and they are well worth the added expense. See, Turkey Pans bolt under the carb, and over the intake manifold, so if you wanted to do somethink like change the little cam for the squirter, or even just adjust the idle mixture screws, it's almost impossible to get your hands down there. I tune my carb with a vacuum gauge and I don't think I could even get the hose on the fitting under the front of the carb if the TP wasn't removable. Some TPs have little holes in the side, which helps, but if you want to do somthing other than just turn a screw a TP that is not removable becomes a huge PITA.

[undy]

Short of stack injection the dual 750s with the Tunnel Wedge really tripped my trigger. The setup works terrific from idle to 6200 RPM, no flat spots or dead areas anywhere. The idle, part throttle and WOT AFRs were text-book on the chassis dyno too!

Barry_R can hook you up with a custom set of QuickFuel carbs (like mine) too.

[patrickt]

Now on the other hand, Undy would have no trouble getting his dainty paws in there to switch out the pump cam.

[elmariachi]

Pat, you aren't doing a very good job of convincing us that less is more.

Dennis, doesn't your car have a tunnel wedge intake?

Jim

[patrickt]

Originally Posted by elmariachi

Pat, you aren't doing a very good job of convincing us that less is more.

Well, it's pretty clear. If you want more power, and more WOW factor when folks are looking at your carbs, then you go for the dual quads. If you enjoy people staring at your Turkey Pan and saying "WTF is that?" then you go for what I have.

[elmariachi]

Originally Posted by patrickt

Well, it's pretty clear. If you want more power, and more WOW factor when folks are looking at your carbs, then you go for the dual quads.

Or if you don't mind stopping twice as much for gas as your buddies with only one carb...............

[Flygirl]

I do really like the look of the turkey pan, although there must be some setups with a custom pan for dual quads.

[patrickt]

Originally Posted by Flygirl

I do really like the look of the turkey pan, although there must be some setups with a custom pan for dual quads.

There aren't. El M., I win.