webers vs CIS

Are webers considered an upgrade from the stock CIS systems on a 74 911? If so, why? Is adjusting webers a hard thing to do? They look so intimidating to me.

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Mark Isaak
'74 Targa

Better is relative to your needs. The carbs give you more horsepower though. I think about 10hp. Your trade off is gas mileage though. Also you need to check what your smog requirements are in your state to see if they are legal on your car.
Bobby 72' TE

I wanted to hear more on this as well, so I placed a responce to get the top back on top.

It would seem that a set of well tuned Webers or even Makinui's would easily out perform CIS.

Anyone gone this route?

I don't know much about CIS -- but one advantage of it is that once it is set up properly, it stays that way. Cold, hot, whatever. Not nearly as much fiddling as w/ carbs.

Webers sound 200% better though, no doubt.

Webers don't really start to wake up an engine until you decide to get deep inside and do some hotrod work with cams and pistons ... a 9.5:1 compression engine with Solex, 'E,' 'S,' or GE-40, 60, or 80 cams can turn heads and get the adrenaline going as it gets on the cams!!!

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Warren Hall
1973 911S Targa

My experience has been:

I never liked or understood carbs. OTH, the CIS is so simple and you can get a manual just for the K-Jetronic system from the manufacturer that explains all. I had a 74 and loved on that one and every one I've had since. I stick with the older ones just ot keep the K-Jetronic i don't like computer chips since I can't get my hands on the internals (and I'm a professional computer guy!). For me the extra horsepower I've heard you can get isn't worth it. I tuned each of my 911s CIS once and never messed with them again. If any of the peripheral parts get out of whack (warmup regulator, etc) I don't mess with testing them, I just replace the part with new and it works perfectly. I guess this is just a lazy man's opinion but I find the 911 is powerful enough for my needs just as the factory made it.

The Webers give you a throat for each cylinder so response is much crisper and maybe a few more horse power. With cams matched to the carbs there would be a much bigger effect. Carbs seem to be affected by the poor gas we have in CA now so if the car sits for a week or two then you get that goop that forms in the float bowls and won;t come out. You could do even better with a programmable FI system and individual throttle bodies but the cost is really high.

I have heard that CIS can be pretty darn good once it is modified. A fellow here in Colorado opened his up using some VOLVO parts. I am here to tell you that it did in fact make a diffrence. He is going to put in some cams and then he will tune her up. In the mean time, I will try to run down some part numbers etc for us!

I'm glad folks besides me have spoken out for CIS, so I can play 'devil's advocate.' But first...Tog is right on. I've owned CIS cars continually since 1984 and, once they're adjusted, you just check them for kicks once in a while. If they act up, a component has failed. find out which one, replace it...voila. They start and run as if they're all warmed up, regardless of engine or air temperature. they are fuel efficient as well.

Now for the best part. Carburetors are cooler. No doubt about it. first, they clean up the engine compartment and they look really tough (that's old guy talk for 'cool'). If I had them on my car, my oil thermostat o-ring would be easily reachable. As it is, I'll remove my engine to get at it rather than reach around the CIS. Really. I'd like to open my hood and see six carburetors on tall intakes.

Next, they SOUND cool. You can hear them such air and growl. Cool.

Finally, they are virtually necessary after engine modifications. CIS systems have fixed 'mixture curves' for wont of a better term. They are designed to operate at a particular engine air volume range.

No, I don't think they woudl be finicky to maintain, but they would require checking from time to time.

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'83 SC