Ok since my 383 is almost ready to be lowered into the car i had to figure out a way to solve the cam and crankshaft trigger for my Autronic Sm4 system. This is what i came up with. What do you think? The Sm4 need a 4-tooth on the crank and a single zero sync on the cam @ tdc.

Please feel free to comment.

This is the crank trigger. I cutted it from 3mm steel in a lasercutter. As you can see it´s fully adjustable depending on where i can fit the sensor


Here i have began to make the camsync. I used the standard oli-pump drive and threaded the top of it. Then i made a separate piece and tight fitted it so it guides up with the standard shaft. Only needed a lathe and a mill to make this.


Here´s the camsync installed and ready to go. I had to mill a small bracket for the sensor. Using self locking washers and a lot of oilresistable loctite so it stays in one place but if it falls loose the engine stops so no problem.


The reason that i made my own is two things, the aftermarket is expensive ( this was´nt ) and the other reason is that i have´nt find any aftermarket that i´m satisfied of yet. I now only use the optispark so send the spark.

/Svante.

 

Even though I know nothing about this subject, your setup looks very interesting.

 

LOL. problem was that i did´nt find any trigger system for my aftermarket ECU, that´s why i had to do this. The thread was mostly started to see if anyone had done anything like this before. Because i don´t know if it works yet

/Svante.

 

I've made my own crank triggers in the past for different projects, and I'll tell ya that the notches or ecentricies have to be exactly like the ones from the factory setup for whatever your using. And it always smart to have it based on the crank and keyed so that there isn't a possibility of the timing changing.
For example: if the ECM is looking for a high pulse from the hfet that is only .015 sec in length and it sees one that is .15 sec in length, it's gonna go apesh!t. And vise versa, if it's looking for a low And gets a different length of signal then it's not going to so what you think it should.
Usually GM crank trigger setups have an even o respective number of triggers and a reset trigger to tell the computer where the crank is in it's rotation. For example: the 60 degree V6 uses a reluctor wheel that is actually the crank it's self, the notches are cut directly onto the cranks balance weight and it has 7 notches. These notches indicate tdc for the respective cylinders. The 7th notch is located closer to the 6th and further from the 1st, this indicates the restart count of the high signals. It's allows the computer to see what's going on and where the next cyl to fire is.
The single notch on the cam is to mark where the cam is in reference to the crank, using this the computer can detect which cylinder misfired ( cause it knows which cyl is firing and which is on the combustion stroke vs which is on the exhaust stroke). This is also how the compute controls the sequential injection.

I take it this is using a different setup than the optispark, which has 360 slits in a metal plate for the high resolution and less for the low resolution. Do you have more details on the ECM your running and what ICM you're using?

 

Sure. Here you can read anything you like on the Autronic Sm4
http://www.mrm-racing.se/index.php?pageid=SM4e

I have made a similar setup of the trigger for my other Vette. But that is a l98 from the beginning so the camsync is in a modified distributor.

But the crank setup i pretty much the same.

Here´s a picture of the recommended crank and cam trigger for the Autronic.

It´s based on a 4-cyl engine the crank need 4-tooth for a V8

http://www.mrm-racing.se/bag/Sm4Scyl_triggerHHe.pdf

/Svante.

 

If it helps, http://www.eficonnection.com makes a setup to run an LT1/4 with an LS computer.

 

Well that would have been a good thing to have, if i was using separate coils and CDI ignition, but now i´m in the need of a distributor to send the spark :/