Im wanting to swap to a rear mount HEI style distributor. I saw on a show about using dual sync distributors to accomplish this on fuel injected vehicles. I did a search and found hardly any info other than it is possible. So,....you guys that have had the ***** to try it, how did it work out for ya and how hard was it to re-wire this setup for a STOCK PCM type setup. I understand the basics of why you need the dual sync but how tough is it to get this working? Also, I was wondering if you really need to pull the engine to drop it in, or if you can remove the intake and distributor together as I know theres no way in hell it will clear the cowl but if you pull it up as far as possible, with the intake unbolted, is it possible to install it this way as well? Theres rarely a need to remove one of these I know, but im wondering if I can do this mod while the engine is still in the car. Of course, if I really cant do it this way, you could always just unbolt the K-member and drop the engine down some to give a little more clearance right? Please give any suggestions, Ive had my fill of messin' with opti's all the time. And whoever keeps saying loss of low resolution pulses are uncommon, go fu<k yourself, lol. Ive had this code 3x so far and I tried different harness' also, so its not all that "rare".

 

Nobody here has a rear mounted distributor on an LT1 WITHOUT using the opti for a trigger?

 

The stock PCM will simply not run the engine without the low res pulse pattern from the Opti. Your choice is to keep the Opti simply for the optical signals, or to mount the optical sensor in the conventional distributor. It has been done both ways.

 

From my understanding, this is why you use the dual sync distributor. It has 2 reference signals,...one for the ignition, and the other for the fuel injection. Correct me if im wrong, but thats the purpose of the high and low res. signals that the opti gives out also. From my research, thats what this dual sync distributor was created for, to retro back to a traditional style dist. but still able to maintain fuel injection. Let me see if I can dig up the info again.

 

Run a vortec style dual sync distributor with a vortec ECM. All your sensors will carry over.

 

Where will that leave me for tuning though? Can you still use tuner cat for this? Ill be adding a S/C soon and will need more tuning. Im already running a cam/1.6 RR/Full exhaust/CAI/58 TB/2500 t.c./3.42's/ and soon ported LT1 heads. Also would I need the vortec harness or can I splice the distributor into my existing LT1 harness? Thanks

 

Can you verify that the "sync" signal from the dual-sync distributor exactly matches the variable pulse width low res signal from the Opti? The LT1 PCM needs the exact pulse pattern, which consists of unique slot widths for four designated cylinders, alternating with fixed width slots for the other 4 cylinders.

 

Fred (if your question was directed to me?)-
With the vortec stuff, you also much run the vortech ECM.


TunerCATS has the software to tune Vortecs with, but it is not included in your current EE definition files.

Ive actually seen the swap done locally, so i know it works. I didnt get all the details however. I would assume that you need the Vortec harness as well, but all its connections go into the LT1 sensor stuff.

 

No my comment was for blown94, who seemed to feel that because there is a "sync" signal coming from the dual-sync distributor, it was inherently compatible with the LT1 PCM. I don't think that's the case.

What you said about using the dual-sync with a Vortec PCM is clear and not what I questioned.

 

I think you are correct. I believe the distributor I had in mind is specific to a certain fuel injection setup that they were working on. After further researching it I think I better understand what needs to be done though so thanks for your help guys. Its clear you would have to incorporate the trigger wheel and optical eye into the dist. to have it function properly. So the low resolution signal is the 4 slots (for spark X 2 revolutions) and the high res. signal is all the tiny slots around the trigger wheel (which are for the fuel injection timing, like a cam position sensor)? I understand it doesnt HAVE to be in the dist. to work (ie. deltec) but I was looking to remove the whole opti.

 

The low res is 8 slots..... one for each cylinder. Four of the slots are the same width, so the PCM can not identify them directly. Each equal length slot has a variable length slot in between it. Each of those 4 slots represents a specific cylinder, identified by the number of degrees of rotation on the slot. The PCM can identify each of 4 cylinders from the number of degrees of rotation (it has to compare the length of the "on" pulse from the low res slot to the number of pulses from the high res slot) and knowing the firing order can identify the next cylinder with a fixed length slot.

I can post the diagram of the wheel, with the lengths of the slots and the corresponding cylinder numbers if you want.

I watched the guy who built my setup... Opti optical sensor feeding MoTeC M48Pro with an 8-channel ignition driver and 8 LS1-coils.... try to break the code on the sync signal from a Viper V10. He was trying to set up a 10-coil system for a Viper engine he was putting in a 70's Barracuda.

 

Yeah could you post up that diagram man, that would probably help me understand it a little better, although I have a good idea what you're talking about as Ive studied this wheel more than once already, lol. Quite frankly im getting sick of looking at them everytime I get a loss of low resolution pulse after my water pump decides to puke all over the opti or whatever other reason they decide to crap out. P.O.S.'