I understand that. But can't you get TDC info from dizzy hall-sender and skip the aftermarket sender on the rear? It rotates in synchrony with cam, no?

Sure, the dizzy would work fine to detect TDC, but mine doesn't have a hall-sensor? Does yours?

Is there an aftermarket hall-sensor that can be fitted to our dizzies?

Trog,
Cool project.
The 3.6 distributors have a hall sensor. They would also support twin plug. I believe you could take the guts and put them into another early distributor, too.
They are modestly priced, as well.

Before Goran wrote to you, I was thinking it would be far easier to use the distributor than adapting the signal to the cam. Also, I would suspect you could add an aftermarket hall sensor. I can't believe this is treading on much new ground.

Doug

Though on how to get the cam out. Would it work to drill a 1/4" hole then tap it. You could then thread a bolt in and as you put the bolt in it would push the plug out. Not sure if that would put to much pressure on the oposite end of the cam. Just a thought

I thought of that, however like you, I'm concerned about the loads on the cam. No worries though, I just picked up a slide-hammer. I plan to attack this task tomorrow. Stay tuned.

How much clearance is there between the cam and plug. Will there be enough room to get a screw or what ever to go in enough to hold before it hits the cam.

There should be some sort of sensor there in order for Motoronic to trigger?
There are converters that can translate from variable-relictance sensor to Hall sensor. Also, some EFI (MSII for example) can be configured for both Hall-sensor and VR sensor.

I believe the Motronic relies on the reference sensor located at the flywheel.

Progress Report #4
 

Qapla (Klingon for success). The cam-end plug is out!

It took a couple of tries. Here’s how I did it.

First, I carefully drilled a small exploratory hole in the center of the cam-end plug to see just how far back the camshaft rests. In my case, the cam was about 2mm behind the back of the plug. Not good.

http://forums.pelicanparts.com/uploa...1221619089.jpg


That was going to seriously limit my options. No way was I going to be able to tap the hole, or thread in a sheet metal screw to accommodate a slide hammer. So, I drilled a second small hole adjacent to the first one a threaded some baling wire into a hoop.


http://forums.pelicanparts.com/uploa...1221619127.jpg


I then attached the slide hammer and gave a couple of tugs…. The wire broke on the third tug….. Damn!

OK, so that was dumb. I then drilled a larger hole next to the small one to create a keyhole. I located a flat-headed screw that fit behind the plug and secured it into the sliding hammer chuck.

http://forums.pelicanparts.com/uploa...1221619053.jpg

A couple of tugs of the slide-hammer and out she came.

http://forums.pelicanparts.com/uploa...1221619174.jpg


Here’s a coupe of shots of the tool assembly and the back of the cam.

http://forums.pelicanparts.com/uploa...1221619215.jpg
http://forums.pelicanparts.com/uploa...1221619250.jpg

Be sure to use a magnet to remove all the metal filings.

Next, I’ll be drilling and tapping a hole into the back of the cam. The cam-sensor comes with a drill guide to ensure the hole is square. The instructions state that I have to place the crank 90-degress before TDC on the compression stroke. Then use the cam-sensor mounting plate and drill guide to drill your hole. Accuracy is not all that critical. I believe there’s an 80-degree window to locate the target. I presume the cam-sensor triggers a flag in the TEC-gt software to tell it that the next crank-trigger will be TDC on the compression stroke.

I’ll cover the cam-sensor installation in my next progress report.

It seems that CDI box (on cars without Hall sender) relies on six-pronged trigger in distributor to know when to fire CDI (and generate spark).

So theoretically, only thing you need to do to generate TDC signal from distributor on non-Hall equipped 911 engine is to:
1. Remove five prongs and leave 1:st cylinder prong (or configure EFI to 6-tooth signal).
2. Lock/remove mechanical advance signal.

In that case cam position sensor isn't needed anymore, even if you want sequential ignition/injection.

CDI schematics can be found in this thread, courtesy by Warren Hall (RIP):

http://forums.pelicanparts.com/porsche-911-technical-forum/226517-history-bosch-cdi-toubleshooting-info-parts-list-changes-schematics.html

I understand that you want to install cam sensor anyway, but it's a interesting possibility.

Outstanding project! Wish I was up to it for my car.

Just a thought. I know a sophisticated aftermarket EFI offers some advantages but why not consider using the stock Motronics w a Vac sensing conversion from Prototec instead. Would save a lot of effort getting alternate sensors in place, wiring and such?

Because it wont look nearly as cool as this:


http://forums.pelicanparts.com/uploa...1221663647.jpg

Oh that is sexy! Be still my heart...

There is not reason for it to look different except it would need a dizzy.

My dizzy is long gone. I've been running a wasted-spark system for about a year now.

http://forums.pelicanparts.com/porsche-911-technical-forum/320455-vitesse-racing-wasted-spark-ignitions.html?highlight=trog

Trog,

Great stuff! It is really fun to follow your progress.

Two questions if you will: What is the diameter of the two holes in the end of the cam (not the one in the center). and what is the depth from the end of the cam to the flat surface that has the three mounting holes for the Clewett sensor?

Brian

Brian, I'll get back to you on these dimensions in a day or two.

Progress Report #5
 

It's time to complete the cam-sensor installation.

With the cam plug removed, rotate the crank until you’ve reached 90-degrees before TDC on the compression stroke. No need to be balls-on accurate as you have an 80-degree window.

The Clewett cam-sensor comes with a pretty comprehensive set of installation instructions, so I wont repeat the details here. I believe the instructions are available on the Clewett website.

As I’ve been running without a dizzy for some time now, finding TDC without removing the valve covers can be a bit tricky. Fortunately, I have the infamous ACME inflatable TDC detector in my toolbox. Simple to use… insert tool, rotate crank, when the balloon inflates, you’re found TDC on the compression stroke.

http://forums.pelicanparts.com/uploa...1221711026.jpg

http://forums.pelicanparts.com/porsche-911-technical-forum/393216-porsche-mother-invention.html?highlight=trog

With the crank at 90-degrees before TDC, install the Clewett cam-sensor mounting bracket and the drill guide. Drill a 4.2mm hole 13-16mm deep.

http://forums.pelicanparts.com/uploa...1221711072.jpg

Flush out the filings with solvent and a magnet. Chamfer the hole, and then tap the hole with a M5-0.8 thread.

http://forums.pelicanparts.com/uploa...1221711108.jpg

Again, clean out all the filings. Then install the bolt.

http://forums.pelicanparts.com/uploa...1221711141.jpg


With the bolt lightly tightened, install the cam sensor and bracket and check tolerances. The top of the bolt should be 33.0 – 33.5mm to the top of the cam sensor-mounting surface. If too close, add another gasket under the cam sensor-mounting bracket. If too far, place a washer under the bolt. In my case, I had to add a 1mm thick washer under the bolt to satisfy the recommended gap.

http://forums.pelicanparts.com/uploa...1221711179.jpg


When you’re satisfied with your installation, remove the cam-bolt and reinstall with Loctite 271 (red).

Next task will be to re-install my exhaust and the engine tin. I’ll have to cut a hole in the tin to accommodate the new cam-sensor.

I would give this task a difficulty rating of 2.5

Brian,

The diameter of the two holes is 3/16" (and have a depth of 29mm).
The depth of the end of the cam to the flat surface is 13mm.

I trust this helps.

T...

Trog,

Most helpful. Many thanks.

Brian

Progress Report #6
 

With the crank and cam sensors installed, it’s time to focus on the wiring. The TECgt manual is very comprehensive. With detailed wiring diagrams and installation recommendations. Still, you have to decide where you want the major components. I elected to install the TECgt CPU, fuses, and relays under the drivers seat in place of the Motronic. In addition, I decided to use industrial terminals for the power distribution. This is strictly optional but I feel it will help with troubleshooting should it be necessary.

The first step in the installation is sourcing a constant 12VDC and a switched 12VDC source. The switched power source must be “Hot” with the ignition switch in both the engine cranking and running positions. Fortunately, the DME relay offers these signals. In addition, the DME provides a good source for the system ground and power to the fuel pump.

In order to take advantage of the DME relay location, I gutted an old DME relay I had lying around. The specific pin-outs are:

Pin #30 for constant 12VDC
Pin #85 for ground
Pin #86 for switched power (cranking and running)
and Pin #87b to send 12VDC to the fuel pump.

The following photo’s are self-explanatory:

http://forums.pelicanparts.com/uploa...1222231389.jpg

http://forums.pelicanparts.com/uploa...1222231409.jpg

http://forums.pelicanparts.com/uploa...1222231432.jpg

The following photo shows one of two backplanes. The forward most backplane has the fuses and relays in place of the Motronic. The location allows easy access to the fuses and relays should replacement be necessary.

The TECgt CPU and wideband-O2 controller will be mounted on a separate backplane, just aft of the relays.

http://forums.pelicanparts.com/uploa...1222231484.jpg