Hp advantage of carbs over cis

[greyes59]

I have a 1979 3.o cis motor and modified it a ff:

964 cam
backdated exhaust
je 9.5 to pistons

if i change my cam to 911s and use weber 40, about how much more hp will i gain? Is it worth the cost and trouble to do this second upgrage?

[Scott R]

I'm getting power on the dyno from my CIS than I did with my webers, and I have this same engine configuration. If you decrease the warm control pressure and use a euro SC distributor (or have yours re-curved a bit) you'll do better than webers and be able to retain the warmup characteristics of CIS.

[greyes59]

Wow thanks for the useful info!

[greyes59]

Where did you have your distibutor recurved?
I have an adjustable wur regulator. Can you tell me what warm up pressure value you recommend?

Thanks

[Scott R]

Barry Hershon did my distributor to euro specs and removed the retard pod. My WUR is from Brian Leask and has been modified with an "HD Diaphram."

Control pressure is 3.2 bar
CCP is 2.3 bar at 20 deg C

If you make these small adjustments you won't be disappointed. I pulled about 10hp more over the carbs at 33 deg advance after this and my CO% is still within emissions spec.

[RWebb]

El Centro = Calif.? CARB issues?

carbs will give you much better throttle response rel. to CIS