How Streetable is this configuration of an SC
 

I'm considering buying a '80 911sc with the following tweaks:

* Stainless steel headers
* Dual in and out exhaust
* Weber 46 IDA Carburetors

Are the webers a pain to maintain compared to the original fuel injection? This car would be for the street, as a toy 3rd car.

Do the webers kill your fuel economy?

Advice please!

David

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Don't have an SC, but I can tell you that the car would sound great with headers and carbs! All your neighbors are going to absolutely love you.

Carbs are more tempermental than CIS, but if it's a weekend fun car its manageable. 46's might be a bit big for an apparently otherwise stock 3.0L street car motor though.

Yes, the carbs will kill the fuel economy, but for a fun weekend street car, who really cares??? Hopefully you don't have to worry about smog issues???

Ralph

I'm running a similar setup in my '66 except I have 40mm (36 venturi) Zenith carbs. The only problems I see are poor fuel economy and possibly reduced torque due to the 46mm Webers. I think 40mm are better suited to the street for a 3.0. My car has great torque but it's also a lot lighter than an SC. I get 10-12mpg around town sometimes more if I take it easy on it (rarely). Once you learn how to tune carbs they are simple, mine rarely need adjusting. The exhaust will give you a nice HP boost over a stock SC. Since the car is a toy, I don't see mpg being a factor, mine is also low due to low gears in my 901 so my motor spins faster than if I had a 915 with stock gears. For example I'm always over 3K rpm on the freeway. I also have my idles an mains jetted on the rich side in the event I get some bad gas, I'm sure I good be up around 15 mpg if I leaned it out a bit.

David,

Are these OE 46IDA Webers or PMOs? What is the size of the venture? Does it still have the SC cams?

With a good set of PMO 46s and appropriate (small) venturi, this set-up can work great and get acceptable fuel consumption with proper adjustment.

You don’t list your location. Are emissions testing an issue for you? Does the car come with the CIS parts?

Best,
Grady

I'm in Minneapolis, and am waiting for more details on the engine rebuild.

You guys don't have smog checks in Minneapolis?

Great top end...a Pinto will beat you off the line though....

I have an '83 SC with a lot more tweaks than that, with 46mm PMOs on a 3.4-liter twin-plug engine, S cams, headers, two-in-two-out, etc. etc. It's a marvelous street car, and with 290 hp at the flywheel, ain't no Pinto gonna beat me off the line. Just did about 500 miles to/from Watkins Glen plus track time and got over 17 mpg.

Twice in the last two years I've had to blow a speck of dirt of some sort out of an idle circuit--these carbs hate contamination--but that's a piece of cake to do. Other than that, once I had Rick Deman of Deman Motorsports (Nyack, NY) set the carburetors up properly, the car has been trouble-free. Noncompliant suspension, big torque tubes and some other stuff make me avoid stray twigs in the road, but that has nothing to do with the engine.

Agree that 46mm might be a bit too big, though.

Stephan

I agree...but it takes more than than just tossing carbs and headers on a 3.0 to make it perform on the bottom end.