I got the car 4 years now, 81 SC. usa model.
CIS drove good, i have nothing really bad to say about how it drives...when it runs properly. I loved driving it, MUCH more fun than my 1969 T on carbs.
then winter came, and i noticed that my WUR wasn't working properly, impossible cold starts, started learning about jetronic, WUR fixed, then i had other cold start issues, chased it for months until i found a block off plate in the CSV flange.
The car seemed to run fine, until i put on a wideband gauge and noticed pretty awful AFR's.
Started digging further into the whole system...WUR still not good, AAR not working 100%, lambda system not doing what it should do, etc
honestly, 81-83 USA CIS cars are a complete mess, and are ridiculously hard and expensive to troubleshoot and fix. You got that whole array of stupid bandaid junk and overcomplication (AAR, AAV, decel valve, etc etc etc) and the lambda brain is a big black magic box which nobody knows how to fix or check. 78-79 cars are a little bit better i presume.
I bit the bullet 2 years ago: i decided to not spend another dime on an old and flawed fuel intake system (no new parts available and super expensive crappy second hand parts) and changed over to Bitz kit, installed it in a couple of days, tuned it on a dyno, and drove 1,5 years without any issues, loved it. -10°C starts each and every time.
Last month, my old distributor failed, no way i'm buying a 40 year old 2nd hand dizzy for 1500 €, and i swapped to full EFI with distributorless ignition. Got the car running from the first crank. I am not looking back, screw resale value, screw originality...i just want to use this car and drive the hell out of it, not worry all the time when the next 2000€ thing will break. Gimme modern reliability, power, driveability and old skool driving character, yes please.
some people should be a little bit more honest with themselves and just aknowledge that 40 year-old lambda CIS is old junk, plain and simple. it really is. Overcomplicated bandaid engineering.
But i do love the 915
it's mechanical, deliberate, feelsome...and hasn't missed a shift in 4 years, so reliable as well? knock on wood.