Dumb questions about my 79' SC - CIS

[Hulley]

A couple questions,

1. Is the CIS a stand alone system?

2. Is the ignition system a stand alone system?

The main thing is, is there a main DME that if I were to change the fuel injection and/or ignition system, would that effect any other body functions? I did a search and cannot seem to make the determination that the 79' SC even has a DME.

For example, if I did a PMO carb conversion, would I have to reprogram a control unit to not look for the CIS? or would it be as simple (right?) as removing the CIS system/wiring/control unit and then installing the carbs and of course correct fuel components.

Thanks,

[icarp]

A simple swap, Why would you want to change?
Power? CIS not working? feel like spending money?
Ian

[Hulley]

Originally Posted by icarp

A simple swap, Why would you want to change?
Power? CIS not working? feel like spending money?
Ian

Well, the car is actually running great, so no hurry on my end. A little more power or responsiveness would be nice but I really want a nice, clean looking engine bay. The goal is to build a nice little motor someday but mine is currently in excellent shape.

So basically, feel like spending a little money.

When you say "a simple swap" does that mean that the CIS is a stand alone system? No DME?

[boyt911sc]

Originally Posted by Hulley

Well, the car is actually running great, so no hurry on my end. A little more power or responsiveness would be nice but I really want a nice, clean looking engine bay. The goal is to build a nice little motor someday but mine is currently in excellent shape.

So basically, feel like spending a little money.

When you say "a simple swap" does that mean that the CIS is a stand alone system? No DME?

Hulley,

Your 1979 SC does not have an ECU nor DME. If you have a desire to make your CIS motor to run faster and quicker, contact Ian Carpenter (ICarp). I had been on Kermit and could not believe how well this car with CIS performs on the road. I though it had carbs in it.

Tony

[RDM]

The first step in cleaning up your engine bay is a heater backdate. This is aided by installation of SSIs, which will get you a bit more responsiveness and performance. Many threads on that topic.

A CDI+ box will give you programmable spark advance, which again gives you a bit more responsiveness and performance.

And no- no DME. No interface between intake and ignition systems.

[MichaelSJackson]

As stated earlier, no DME/ECU on a '79 CIS. My CIS never gave me any problems.

I'd also agree the fugly-est thing in the engine bay is that heater fan and the plastic and paper hoses running all over. But heat might be a requirement? (It is up here in PNW.) Later models hid two fans up front. If you have a sunroof, cracking it open about an inch creates a vacuum that pulls more heat than the heater fan ever does.

CIS has a large air-flow meter plate that is sensitive to blow-back that might be caused by intake valves opening too early. Therefore, you'll read about CIS owners trying to find the best cams that don't step over this line. Or they replace the CIS. Maybe your driving goals won't require you take that step? It's already a Porsche and has wonderful performance.

If you start down the slippery slope, it's a good idea to know where you are going to get off.

Michael J.
'78 SC (CIS replaced by BITZ EFI)

[HaroldMHedge]

Based on your questions about CIS, ignition and DME you need a better understanding of the CIS system before making changes. May I suggest you review the CIS Primer for the 911.

[Hulley]

Originally Posted by RDM

The first step in cleaning up your engine bay is a heater backdate. This is aided by installation of SSIs, which will get you a bit more responsiveness and performance. Many threads on that topic.

A CDI+ box will give you programmable spark advance, which again gives you a bit more responsiveness and performance.

And no- no DME. No interface between intake and ignition systems.

Thank you, I had seen where a guy had backdated his heater and looked pretty good, definitely on the radar.

[Hulley]

Originally Posted by MichaelSJackson

As stated earlier, no DME/ECU on a '79 CIS. My CIS never gave me any problems.

I'd also agree the fugly-est thing in the engine bay is that heater fan and the plastic and paper hoses running all over. But heat might be a requirement? (It is up here in PNW.) Later models hid two fans up front. If you have a sunroof, cracking it open about an inch creates a vacuum that pulls more heat than the heater fan ever does.

CIS has a large air-flow meter plate that is sensitive to blow-back that might be caused by intake valves opening too early. Therefore, you'll read about CIS owners trying to find the best cams that don't step over this line. Or they replace the CIS. Maybe your driving goals won't require you take that step? It's already a Porsche and has wonderful performance.

If you start down the slippery slope, it's a good idea to know where you are going to get off.

Michael J.
'78 SC (CIS replaced by BITZ EFI)

Heat is a requirement as I like to drive year round, it doesn't get that cold here but heat is nice. The car does run quite well right now so I am hesitant to make any changes anytime soon but still want to have a plan.

[Hulley]

Thank you all for the input, Pelican really is a great place to be!