spyderman

ok,

here is what I got, a 2.4 T motor with cis, i rebuilt it, shuffle pined, oil bypass mod, cut the heads, align bored the case, new bearings, valves, springs, guides, chains, tensioners, RS pistons and cylinders, bored the intake port to 35mm, stock CIS, stock T cams, SSI's and a sport muffler. This motor along with the stock trans, makes for one great street motor, there is not waiting for power. in second, at 1500 you step on it, and there is instantly response. untill about 5500 rpms, the the power drifts off. what i want to do now is get some more top end, but still keep the great bottom end. my firt option is a set of webers, with everything else left alone, I should have more top end, but will the bottom end be the same? also I could install the webers with a set of GE-40 cams, i would definatly have more top end, but what about the bottom? what i want in this motor is a hot rod street motor, that is also good for the track. any suggestions or direction?
-Thanks

Steve Weiner-Rennsport Systems

What you are feeling is completely normal.

Chalk that up to those T cams and some CIS limitations.

I would suggest different cams (Solex or GE-40's) and a set of 40mm PMO carbs, properly setup and jetted of course. That will make your engine do what you want.

spyderman

cool,
Will I still have a good bottom end? I drive it almost everyday, so I need a lot of torque on the bottom end. it is sort of a daily driver for me. how badly will it suckdown the gas?
-thanks

Steve Weiner-Rennsport Systems

As longas the carbs are configured & jetted right and you use the cams I recommended, you will be fine.

There is no question that CIS cars get better mileage than carbureted ones do, but the performance is incomparable.

FWIW, my 2.7 twin-plug, S-cammed motor gets 17 mpg in town and 27 mpg on the road. Very aggressive driving nets me 12,....

Chris Picklo

27 mpg - that's crazy!

How is your throttle response?

I'm guessing what Steve mentioned would enhance it quite a bit.

Steve Weiner-Rennsport Systems

Hi Chris:

IMHO,..carbs get a bad rap,....

Throttle response is neck-snapping, razor sharp. Its all about proper venturi selection, jetting, fuel pressure and very careful attention to float levels.

spyderman

Hey Steve,

What do you suggest for venturi size, and jetting? can you really get 28 MPG? that sounds almost too good to be true.
Thanks
-Ken

Steve Weiner-Rennsport Systems

Let me know what your final engine configuration will be and I'll make some recommendations.

Mileage is all about dealing with many factors:

Engine configuration

Engine tune; ignition, carbs, valve adjustment, compression, etc.

Tires and pressures

Chassis setup

27 MPG is possible, but everything must be spot-on and you gotta drive it gently,...

spyderman

Steve,
Here's what i got, 2.7 RS pistons, on a bored out 2.4 case. stock valves, intake ports bored to 35mm, exhaust stock, ssi heat exchangers, sportmuffler. ill be using the GE-40 cams. the heads were cut, so that will raise the compression a little.
thanks
-Ken

Steve Weiner-Rennsport Systems

Ken:

Depending on where you want your power to come in, I'd use:

1) 34mm or 36mm venturies

2) Tall aux venturies

3) 155 main jets, 180 Air correctors

4) 60 idle jets

5) F3 emulsion tubes

Set fuel pressure to 3.5 psi and use a regulator. Spend the time to get the floats spot-on.

34mm venturies will make better power from 2500-6000 and the 36mm ones will make better power from 3500-7000.

Hope this helps,

Jim Florance

When I put my motor together I started with a C6 cam and 40 PMO Webbers. The motor screams and has as much or more bottom end and just as much mid range umph as remember my 72 911S had. It pulls like a rocket from 5500rpm through 7800rpm. I don't see many posts from guys using these cams. This car is a used regularly on the street and I have no complaints, the car is a blast to drive and so far I have no problems in traffic or any other driving conditions. I've been told by several people that this is too much cam for a street car. Why is there so much difference between my personal experience and the many comments from other people who supposedly know what their talking about?
I'd really like to hear from others on this, I'm baffled that so few people are running these cams.

Steve Weiner-Rennsport Systems

Hi Jim:

Well Sir,.....the main reason why people do not use those cams anymore for street or race cars is they have some flat spots and reversion problems that are difficult to fix.

Its an old profile and there are much better cams nowadays that retain the upper end pull without compromising the low and mid-range as much.

Try the Webcam 120/104, GE-80 or Webcam 149/171 (more top end) for nice high end power and a much wider RPM & torque range. I'd guess that Elgin has some profiles that retain the C6 cams high end power and much better low end, too.