CIS tuning with the LM-1 and my '80SC

[PcarPhil]

I've had the LM-1 installed in my '80SC for about a week now.

Day 1: Innovate LM-1 and my 1980 911 SC

Since then I fixed a minor vacuum leak and set my CO at warm idle to 3.5 (13.2 AFR) from a previous setting of 4.6. Now at cruise/part throttle the car is running around 13.8-14.2 AFR and at WOT the AFR is around 13.0-13.3.

One thing I've noticed is that it takes a few seconds once at WOT for the AFR to go from 14.0 down to 13.0-13.3.

Soon I'm going to hook up the LM-1 CIS trick and set the AFR at WOT to 12.8. I'm really curious to see how quickly the AFR will change when I trigger WOT (instant vs. a few seconds).

I'm going to try and do some datalogging before and after the CIS trick to see if I can plot any acceleration differences with and without the CIS trick.

Stay tuned,
-Scott

[Hladun]

It's that 14.0 on CIS WOT that's sold a lot of Webers. There are WUR's that have an accelerator pump feature..they're an emissions no-no of course, but you're obviously not meeting emissions. Has anyone ever tried a WUR that richens the mixture on low vacuum?

[PcarPhil]

I've been researching the adjustability of warm control pressures. This should lower WOT AFR.

I'm actually getting 13.0-13.3 AFR at WOT with my CIS (without the LM-1 mod). It just takes a second or two to get there. In other words, it's not intantaneous like the Webbers are.

Hopefully the LM-1 trick will make the 12.8 AFR change instantly.
-Scott

[KobaltBlau]

Cool Scott! I will be very curious as well whether the trick improves the response.

Hladun, What CIS vehicles have this type of WUR, or roughly what could one look for?

[Hladun]

Here's where I learned how the WUR really operates;

Let's Connect the WUR Right

Earlier (non emissions) 911's might have had this type of WUR.