convert to cis?

[pjh69911]

Hi all,
does anyone know what would need to be changed to use cis in a non-cis car? (1972). I know I need a later pump. Can the existing fuel lines be used ? Any suggestions are appreciated. Paul.

[JK-81SC]

If you are considering a change, why not go more modern. Install a EFI system and forget about all of the 25 year old problems with the CIS. Do a search for "cis to efi". Tony (tbitz) has a nice solution, a complete kit ready to install.

[ubiquity0]

CIS needs a very mild cam- you may find you'd need to change cams & pistons.

i.e. its not worth it

[jpnovak]

I guess we need more info. ARe you:

using CIs on a non-CIS motor?
Installing a CIS motor in place of a non-CIS motor.

The first is probably not possible as defined above.

The second is most possible and will vary depending on application.

Fill in the blanks with as much info as you can and we will help.

[pjh69911]

Hi, Thanks all.
I am looking to place a complete cis motor in a 72, non cis car. I suppose the 72 had mfi? I am most concerned with the higher pressure of cis. Hope this helps. Paul.

[jpnovak]

Depending on the year it can be simple. The motor will bolt to the existing 72 tranny. You will have to use a CIS fuel pump and adapt to its intallation. The necessary supply and return lines are present for an MFI car (your 72).
If the motor is post 77 you will need some of the electronics board, (6-pin CDI).

then its just a matter of moving the pin configuration in the 14 pin harness plug so that the later engine pin-out matches the 72 pin-in. Takes about 20 min to swap wires.

Have fun.

[chuckw951]

Your post doesn't provide much detail about your project or your goals. The more you tell us the more we can help

I have a 69 911E which had MFI. I was considering the same swap...pulling the MFI motor and adding a 3.0CIS engine. One of the problems I ran into was fuel delivery. The CIS pump puts out much more pressure than the MFI pump. Something like 100PSI. I was worried that the fuel lines from the pump (under the tank to the engine bay) would not be up to the task over time. One option was to install better lines to handle the pressure, but that is not very easy to do as the line run through the tunnel. So instead I went to carbs. You might be better of selling the 72 and buying a 73.5 911T which came stock with a CIS engine. Seems like a swap into that car would be much easier. Anything can be done, just a matter of time and money. Which CIS engine are you considering? 2.7? 3.0? If a 3.0 consider getting the 78/79 model. That way you don't need to worry about the O2 sensor/02 box.

[chuckw951]

Originally posted by jpnovak
The necessary supply and return lines are present for an MFI car (your 72).

JP,

While supply and return lines are there, are they up to the task of supporting the higher fuel pressures generated by the CIS pump?

[pjh69911]

Thanks all for the input. I am considering a 731/2 t engine into a 72. I am considering this as it is a package deal. My biggest concern is over the high pressures of the cis, and would special fittings or whole, front to back, metal fuel feed line be needed? All I need is a gas leak...

[jpnovak]

It depends on the chassis. My 71 has metal lines through the tunnel and rubber (cloth covered) from there. AS part of the restoration I replaced all the fuel lines.

Yes, the metal will hold the pressure. most fuel line is rated to 250+ psi. 100 is only 40% of capacity. I see no problems.

Yes, special fittings may be needed. It is not plug and play.

The biggest issue I see is just replacing the lines. These simply unclamp and pull off the tub. Keep track of input and return and run lines to the engine through the proper accumulator and filters. I think the 72 has the fuel pump up front. If so, it should be a fairly simple operation. Just make sure to get the banjo fitting for the pump. Any junkyard should have that.