Doc Hawk Posted May 15, 2011 Share Posted May 15, 2011 I alluded to my issue in a recent reply to a similar question, but I realized I probably need to just start my own thread at this point. I am hoping to control fuel and spark on my L28ET with MS Extra on a 3.57 board using a NA electronic ignition module (star wheel, not optical turbo). I know most folks just opt for optical trigger with the 82/83 ZXT distributor, but I bought a turbo car that "supposedly" was running before they took off the turbo to replace leaking oil lines. MS was installed in the car already (badly...) but I get sensor readings. The wiring seems to me to have been for fuel only, with spark left to the stock NA distributor. The coil wiring makes no sense at all... the positive side doesn't even have a line to it or available for it, so I am having a hard time believing the car was running. I think it was an MS install that someone gave up on. Anyway, with the engine in the car and everything hooked up, I would like to try and use the NA distributor. Searching, I see many many folks refer to locking it down to eliminate mech and vac advance... anyone have details on how they did that? Next, has anyone actually used the NA electronic ignition as the timing input for MS? How? What wires from the distributor and which wires from the MS harness were used? How was the coil wired? (-) to tach and pin 36? + to relay power that's on with the fuel pump? Quote Link to comment Share on other sites More sharing options...
dexter72 Posted May 15, 2011 Share Posted May 15, 2011 (edited) You lock the centrifical advance weights in place inside the distributor, so they can't move ( advance ). By either having them welded in place or use JB Weld, RTV sealant to do it. So you have to take the distributor apart. I locked mine out with silicone sealant, I let it sit for 2 days before putting the distributor back together. I did this before adding megasquirt to my car and a turbo distributor. You want to connect the vacuum advance if you do a lot of city driving. There are some posts about the VR Dist which is what an N/a dist signal is. Do a search and those posts will show up. I think some megasquirt users got there engine to run with the N/A Dist. Edited May 15, 2011 by dexter72 Quote Link to comment Share on other sites More sharing options...
Doc Hawk Posted May 15, 2011 Author Share Posted May 15, 2011 Thanks Dexter. I'm squared away on locking out mechanical advance (although your post is the first time I've heard any talk of leaving vac advance connected). I have gathered from the VR posts I've seen that people work on taking the raw signal from the internal sensor itself, rather than the coil signal sent out by the NA ZX electronic ignition control module that sits on the outside of the distributor. As I understand it, using a raw VR signal is problematic because of the widely varying voltage through the RPM range. Isn't there a way to use that regulated ICM signal instead? I don't know what its signal actually looks like; it just drives the coil ground on the stock NA setup. Quote Link to comment Share on other sites More sharing options...
Matt Cramer Posted May 16, 2011 Share Posted May 16, 2011 If the MS is controlling timing, I would not use the vacuum advance, but it can be simply disconnected. The ICM output can be treated as a points trigger, but I'd just use a V3.0 or V3.57 board and feed the signal in through the built in VR conditioner. Quote Link to comment Share on other sites More sharing options...
Doc Hawk Posted May 17, 2011 Author Share Posted May 17, 2011 If the MS is controlling timing, I would not use the vacuum advance, but it can be simply disconnected. The ICM output can be treated as a points trigger, but I'd just use a V3.0 or V3.57 board and feed the signal in through the built in VR conditioner. Thanks Matt - this sounds very exciting. I do have a 3.57 board, but didn't realize it had a built in conditioner for a VR signal. Do you have a page link to the instructions for wiring this setup? I have been doing a tremendous amount of searching and have seen so many threads and MS writeups that mention doing this, but not a single one showing my specific setup. Do I need to use a Chevy HEI in conjunction? 4 pin or 7 pin? Which 3.57 pins do I hook up, and to what? Your opinion on vacuum matches mine. Thanks, David Quote Link to comment Share on other sites More sharing options...
Matt Cramer Posted May 18, 2011 Share Posted May 18, 2011 Thanks Matt - this sounds very exciting. I do have a 3.57 board, but didn't realize it had a built in conditioner for a VR signal. Do you have a page link to the instructions for wiring this setup? I have been doing a tremendous amount of searching and have seen so many threads and MS writeups that mention doing this, but not a single one showing my specific setup. Do I need to use a Chevy HEI in conjunction? 4 pin or 7 pin? Which 3.57 pins do I hook up, and to what? Your opinion on vacuum matches mine. Thanks, David This page explains how to set the jumpers for VR input. http://www.megamanual.com/357/intro.htm A HEI module is not needed if you install a coil driver in the Q16 slot - this wires up very similarly to a V3.0 except the IGN to IGBTOUT jumper has been omitted. Quote Link to comment Share on other sites More sharing options...
mobythevan Posted May 18, 2011 Share Posted May 18, 2011 The HEI modules stuff was for the really old v2.2 mainboard that did not support anything but fuel control. Quote Link to comment Share on other sites More sharing options...
Doc Hawk Posted August 7, 2011 Author Share Posted August 7, 2011 Tidying up this thread... I looked into running the NA dizzy with the mechanical and vac advance locked out, but decided I wanted to go tried and true so I converted to an 83 optical distributor and am running that. Quote Link to comment Share on other sites More sharing options...
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