Thread location help - the simplified CIS
 

There was a thread years ago about taking a later CIS with all the emissions stuff... And stripping it down to simplify it much like the 73-74 CIS.

Can anyone help me find that thread? I have spent a ton of time in the archives and can not find it.

Thanks

Maybe here? A few posts down... Henry...

http://forums.pelicanparts.com/911-engine-rebuilding-forum/865104-how-much-power-increase-3-0-a.html

I might be able to offer some advice, I recently did an R&R on my CIS. All the extra stuff is designed to get air into the engine, either when cold starting, or starting or decelerating. All the extra air enters through the cold start valve. I accidentally reassembled mine with that intake port plugged, effectively backdating the CIS. It didn't add any extra power, but it did make cold starting quite rough. So if you are going to do this you would have to also backdate the WUR, as the newer models will expect more air through the throttle. But IMHO you won't gain any power from the backdate, but it will be simpler to troubleshoot!

Also, you can run the engine with the O2 sensor disconnected (mine is an '82 btw), and it runs a bit better. Idle is smoother. I couldn't feel any power increase, so if there is one its negligible. Mileage may be slightly worse though.

The euro SC CIS is much simpler but you'd have to change out a great deal...dif wur/fuel head.
It controls fuel delivery with the wur vacuum (no lambda/L control unit).
Makes it easier to tune fuel delivery across the spectrum for power. I cruise at an afr of 13.8 - 1 but if I stomp it get an immed 12.3 or so (on board afr)....the mid range is richer too than the normally lean lambda CIS.

i just did this, took apart the whole thing. all youre getting rid of is the 1 or 2 air valves. the ones hanging up by the FD. you definitely want to keep the AAR- the electric one, without it start up is not a happy time. after getting the other valves and associated plumbing out of the way the AAR gets plumbed back in with some creative hose solutions. after i sealed up the airbox and did the runner gaskets and removed the valves in question the car has never behaved better. all the weird gremlins disappeared, it starts immediately and doesnt miss a beat

Jason do you have a write up on what you did? I am still trying to figure out what previous owners have done to mine. I have no Cat or OX sensor and the deceleration valve is there but not the air line that turns it on or off is disconnected. When my shop is up and going i will hunt down some of the vac leak gremlins. Keeping it simple is also what i am after on my 82.