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Registered
Join Date: Sep 2008
Location: Rio Rancho, New Mexico
Posts: 200
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The CIS intake limits the amount of cam duration due to revision and the effect upon the fuel metering.
The stock 2.7 cam runs 224 degrees of intake duration, the SC through carrera cams run 234 degrees of intake timing.
Expecting a big improvement from a simple 10 degree's of additional intake duration without any other improvements is not realistic.
By comparison Solex cams from the early '65 911's run 248 degrees and the "S" cams on the Weber equipped 67/68 911's ran 268 degrees of intake duration.
If you want decent performance from your 2.7, get rid of the CIS, add some 40 Webers, higher compression pistons, open up the exhaust system, and install Solex cams for street use. "S" cams for the track. Dual plug ignition is a great upgrade as well.
Another tact is to dump the 2.7 and go for a larger engine, your choice and budget.
Back dating my transaxle to a 7:31 ring and pinion added substantialy to street performance, at the cost of high end, 125mph plus, speed.
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Doug
Was 2.7racer.
'76, 2.7 w/Webers, JE pistons, Solex cams. Elephant bushings front & rear, 23mm & 28mm torsion bars, big brakes front & rear, Pertronix. Track car.
'85 3.2 stock, Orient red, comfy street car.
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