3.2 46 PMO ignition question

[MRCarrera]

Hi all!

Intro of myself
I will give you a small introduction of myself and my car story, feel free to skip to the next paragraph. I am from the Netherlands and I own a dark grey 81' 911 SC Targa. I bought the car when I was 20 - crazy story, still can't believe I managed to do it - as a project to work on with my dad, I have owned it for 7 years now. We were both new to the classic car world, and it's fair to say we have learned and been through a lot since. Sadly my dad past away at the end of last year after a two year sickness. This project is now extra dear to me and I would sell my house before I sell my 911. Now I do the project on my own and I am not as technical as my dad so it's quite the challenge. I take things slow and careful and hope to get through on this method. Anyway on to the real question!

Engine specs
The original 3.0 engine (US) died two years ago. That 3.0 engine was according to the papers I got with the car enlarged to 3.2 with if I am correct Mahle pistons. Now I have a 3.2 Carrera engine from the EU installed by my Porsche guy. The inlet and outlet systems of the 3.0 have been transferred to the 3.2. Those are: 46 PMO Carburetors (originally made specifically for the 3.0), SSI heat exchangers with a Dansk exhaust and a 123ignition distributor that has been rebuilt to fit the clockwise rotation of the 3.2. This distributor is programmable with an app. Also the 915 gearbox is still the same. Please note that all of the systems were made for 3.0. I don't exactly know what has happened with the inlet en outlet systems when the "new" engine was installed.

Question
Now this engine is not running optimal at the moment, for sure the Carbs need quite some tuning. I want to do that myself with some help from this website. However in order to tune these the ignition and valves must be in order too. Valves is not a problem but ignition is and I am unsure what to do with it.

PMO specifies the following numbers regarding the ignition: The timing should be set 5-8° at idle and between 35-38° at 5000 rpm. 32° is about right for an engine above 9.5-1 compression ratio. My current distributor set up is shown in the pictures below. As you can see those numbers are very different from what PMO suggests. What should I do? Should I recurve the distributor to the numbers PMO suggests? And how can I check if the ignition is correct and healthy for the engine? Also currently the vacuum on the distributor is not used nor is it plugged. Should I attach this vacuum to the carbs or should I plug it?

I hope you guys can help me! Any suggestions are welcome.

[Dmitry at Pelican Parts]

Hello and welcome to the forum!

It's great to hear that you're continuing to take on this project to honor your Dad. I'm including a link to our site's DIY tech articles - I think you'll find them super useful as you're digging into more repairs and maintenance.

https://www.pelicanparts.com/Porsche/techarticles/tech_center_main.htm


We also have a very active and knowledgeable community, they'll be able to assist you as well.

Let us know if you have any other questions!

[MRCarrera]

Thanks Dmitry! Those have indeed been of great help on many occasions already! Sadly I can't find a guide on my specific problem. I have scouted multiple forums but can't find a guide on which curve to use.

[icarp]

MrCarrera, for a proper timing curve, Please repost pictures , Plug any open vacuum from the carbs .
First you must set the 123 distributor to 0* @ TDC, When you do this you can be sure of the accuracy of the timing degrees. To do so ,,,, Once the car is idling it is important to set the baseline of the 123 !!!!!! . turn the car off, now you need to program your timing curve from your phone to the 123 , set the internal curve to 0* through 2000rpm, make a custom curve map with the app, that way you know that you can't make a mistake setting the distributor to TDC and 0*,,,,,,,,, then put a timing light on the pulley, you must then turn the distributor , either way, to match the Z1 mark, on the crank pulley, to TDC, now you know the timing is correct . 0* on the crank and 0* in the distributor .,,,,,,,,,,,,,,,,,, Now you can set the curve that I suggested, or any other . I know my curve is a great starting point .
If you need more help to achieve this projectI understand. I am just assuming that a timing light is something that you know about . Feel free to ask for more direction .

What is your compression ratio, and what camshafts are in the engine

"you can get the 123 app for your phone from the 123 website "

Now you can program your "driving timing curve" from your phone to the 123 ,,,,, @8* BTDC. at 900rpm - 16* @ 1,800 rpm - 24* @ 2,400 rpm - 29* @ 3,000 rpm , this will rewrite and replace the 0* idle start up curve
no need for more advance unless you have dyno access , then maybe 1* to 4* more to 4k or 5.5k rpm all in
I know this works well
Ian

[cabmandone]

Here's a good thread on PMO tuning.
Gordo's PMO Carb Tuning

Looking over your setup, I'm not sure he'll be able to give much advice on it ignition. But his thread on tuning the carbs has a lot of good info.

[MRCarrera]

Hey Ian,

Thanks a lot for your great answer. I will try to work on the car this weekend and try what you suggest. Thanks for the offer of extra help, I should be able to manage I will let you know how it went.

My engine is a 3.2 Carrera from Europe, so the compression ratio should be: 10.3-1.
The standard 3.2 cams are in.

Many thanks again!

MrCarrera

[MRCarrera]

Thanks for your Nick,

In my search for the right ignition I already came across it, I’m for sure going to make use of it.
This forum is amazing it contains so much information!

MRCarrera

[icarp]

MrCarrera,
with that comp ratio and the timing curve I gave you , you should be very close.
Ian
only push the curve if you are on a dyno

[MRCarrera]

I have done what you recommended and the engine seems to knock once I step on the throttle.

I have an adjustable timing light which I used to check what position the idle was at. It said in my previous curve 9degrees. So I put my timing light on there and put it on 9 degrees. And cilinder 1 exactly lined up with the mark on the pulley. So this tells me the distributor is in the correct position right?

After that I have altered the curve to what you recommended. The car definitely idles better but knocks once I step on the throttle. Any thoughts?

[icarp]

MRcarrera, For the 123 program to work you must use the system that I wrote for you
That is the only way to sync the 123,,,,,,, , 0* z1 to 0* to the 123
otherwise you can get an incorrect timing , which is what it seems you have gotten.
let me know what happens
icarp 26 at gmail ........ if you prefer
IAN

[icarp]

please post timing curve pictures