CIS Big bore throttle body
 

http://forums.pelicanparts.com/porsche-cars-sale/1018302-1978-porsche-911sc-ca-car-many-upgrades.html

This listing in the classifieds lists a big bore throttle body and sensor plate. I've never heard of a big bore throttle body for CIS. Now, I know that 78-79 used the bigger intake valves (I know because my brother has it on his '79 and it does make a difference) and perhaps the owner is talking about that.

If there is a big bore throttle body out there, enlighten me please.

Jameel, do you know what size intake valves are on the 78-79?

you can put the 3.0 TB in a 2.7 and go bigger, I did. don't know if there is anything out there for a 3.0 unless you can put a 930 one on there, but I don't think it will work.
unfortunately my car was not running right before I did it so I could not compare before and after.

only place you will notice a difference is WOT. just my opinion.

38mm if memory serves.

I’m pretty sure the U.S. ‘78-‘79 and euro SC used a higher flow CIS set-up, with larger 38mm intake ports. Car and Driver tested a ‘78 SC targa and that rascal was quick. I don’t think it was a fluke. I’ve driven several early stock SC’s and they were all quicker than the later SC’s I’ve driven, even some Carrera 3.2’s.

After reading numerous pros and a few cons (cost and fuel economy mainly), I sourced early heads, CIS, distributor, etc., for my pending build. I feel that along with 964 cams, lightweight clutch/flywheel, and SSI’s I will have a nice gain (currently stock ‘82).

I think the throttle body on all SC's are the same size. The intake runners and ports on some are bigger. The bigger port 78-79 and Euro heads with large port runners and latter 9.3 (or 9.8) pistons is the best power output with everything else being stock. The small port SC engines have the same size runners as 2.7. Headers or early exhaust helps a lot too.

john

Ask the seller? Since he specified a bigger TB and plate, maybe they're custom, someone milled it out and made a new plate.