# Running CIS-e knock box / sensor with 16v carbs



## Justin 123 (Apr 11, 2005)

I'd like to use a cis-e knock box as the ignition source for my carbed 16v so I have a few questions.
Can the throttle switches be safely eliminated? Would putting in a manual toggle switch be a better option?
How dependent is the knock box on vacuum? Is running the vac line necessary? Is tapping one runner sufficient to determine engine load? I'd definitely not like to tap every runner.
Are these diagrams correct?
1) http://www.icstew.com/caddy16v/16v_diagram.jpg
2) http://members.shaw.ca/rgustaf...l.jpg
Where would I pull tach signal?

Thanks guys.


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## Big CADDY (Aug 28, 2001)

*Re: Running CIS-e knock box / sensor with 16v carbs (Justin 123)*

why?
you want timing advance, not retard which the knockbox does
vacuum won't work with carbs unless you use a plenum box and that still doesn't really work. 
Pull a tach signal from the coil.

Just use your ICM, distributor, coil and it will work 
You won't have any timing curve doing it that way, but that requires a timing computer or the dreaded saab distributor.


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## B4S (Apr 16, 2003)

*FV-QR*

I run the CIS-E knockbox setup and it's perfectly fine. I deleted the switches, which isn't optimal, but it does the job. I was originally using the vacuum port off the brake booster one-way valve, with a .030" MIG welder tip in the line to smooth out the pulses. It worked really well, but I recently switched to using two cylinder pulses (tapped the manifold), and it works a bit better. The knockbox has a 3D ignition map in it, basically, and it uses manifold pressure as well as RPM to determine advance. Without cruising advance, you sacrifice some fuel economy, so I recommend using at least one runner http://****************.com/smile/emthup.gif.


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## littlegti84 (Aug 18, 2001)

*Re: Running CIS-e knock box / sensor with 16v carbs (Big CADDY)*

Big Caddy,
I myself have wondered about this... Seems to me if you use your stock distributor, have your timing set correctly, and are running proper octane fuel to coincide with your compression ratio, that you shouldn't need the knock sensor ignition...
Is there any performance advantage to running the knock box? I can see the protection advantage, but is there any other reason?


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## Justin 123 (Apr 11, 2005)

*FV-QR*


_Quote, originally posted by *littlegti84* »_Big Caddy,
I myself have wondered about this... Seems to me if you use your stock distributor, have your timing set correctly, and are running proper octane fuel to coincide with your compression ratio, that you shouldn't need the knock sensor ignition...
Is there any performance advantage to running the knock box? I can see the protection advantage, but is there any other reason?


The reason is that static ignition timing is no good. I need advance off idle. I need a decent curve.


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## B4S (Apr 16, 2003)

*Re: Running CIS-e knock box / sensor with 16v carbs (littlegti84)*


_Quote, originally posted by *littlegti84* »_Big Caddy,
I myself have wondered about this... Seems to me if you use your stock distributor, have your timing set correctly, and are running proper octane fuel to coincide with your compression ratio, that you shouldn't need the knock sensor ignition...
Is there any performance advantage to running the knock box? I can see the protection advantage, but is there any other reason?

The stock dizzy is a vacuum advance unit. How do you propose to utilize it to it's fullest potential without the ported vacuum source needed?








The main reason for the electronic dizzy setup is fuel economy IMO. You can use a vac advance dizzy without the vacuum, the performance will ultimately be the same, but you'll really lose in cruising fuel economy. It's up to you to decide how efficient you want your setup to be. Many folks don't take the time to optimize their carb setups, which results in a lot of carbs for sale after a few months. The rest of us can then swoop in and scoop them up for cheap







. As a point of reference, I'm getting 32 MPG with my dual carbs on CIS-E knockbox ignition.


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