MS-II HEI no spark cranking

[ka67_72]

I have an 8 pin HEI hooked to an MS-II. I have 12v going to the coil and dist while cranking, but it won't spark until I stop cranking. The MS sees it cranking and fires injectors even though there's no spark. Watching with a graphing meter shows no ground to the coil during cranking. The distributor is a cheap ebay one. The same computer on a different motor with a factory distributor fires while cranking. I'm thinking about swapping out the module first. What do you guys think?

Thanks,
Kevin

[dieselgeek]

Are you sure you're getting clean RPM at cranking speeds? Are you running MS2-Extra firmware or B&G code?

[ka67_72]

I'm running BG 2.89. The distributor does the same thing whether or not the computer is on. It advances correctly when running. How should I check the signal while cranking? I have a graphing multimeter and scopemeter if they'll be of use.

Thanks.

[Matt Cramer]

What if you unplug the bypass wire? Will it spark if you try that?

[ka67_72]

I disconnected the bypass from the relay board and it still only fires after I stop cranking. I disconnected the four pin connector and it fires while cranking.

Kevin

[ka67_72]

I went through and disconnected the 4 pin connector's wires individually from the relay board. If I disconnect "G" from ground, it fires while cranking. I haven't tried starting it and putting a light on it to see if it's advancing without the extra ground. What do you guys recommend?

Thanks,
Kevin

[dieselgeek]

I recommend ditching the HEI module entirely as it's not necessary, and likely to fail, which is why so few of us have experience with them.

[ka67_72]

Are you recommending a different distributor or running the hei without the module?

Thanks,
Kevin

[dieselgeek]

The distributor is great! it's the HEI module that sucks IMO. What version PCB is your MS2 running on? If it's a 3.0, 3.57 or higher then you should have the VR circuit built into it already. Feed the pickup signal from the distributor to the MS instead of the HEI, then use either an MSD (or equivalent CDI) box to drive the coil using a single spark output from the MS2.

Randal went through this same conversion, he can probably speak to it more accurately.

[ka67_72]

I have a v3.0. It looks like a pretty straight forward install. I'll start shopping for a CDI box.

Thanks,
Kevin

[TheSilverBuick]

I used a 7-pin HEI for about 3 months then ditched it and fed right off the pickup coil. I was never happy with the 7-pin ignition. I don't know what settings I may of fubar'd but the MSII would loose tach signal randomly on me and that went away completely when I went straight to the pickup coil. I used the same exact wire and wiring, just moved it from the cap connector to the pickup coil. It's so simple to run off the pickup coil I can't see a reason to run the GM module. You could skip the CDI box and control the coil directly if needed be too, but I do run an MSD 6AL box.

Here is a picture of my 4-pin HEI modified and crammed full of 7-pin stuff.



Then the same distributor with the module pulled out. I simply plugged the tach signal wire into one side of the pickup coil and ground the other side right inside the distributor.

[ka67_72]

If there are no objections I'm going to get a 6al-2. I like the built in 2 step.

Thanks,
Kevin

[TheSilverBuick]

If there are no objections I'm going to get a 6al-2. I like the built in 2 step.

Thanks,
Kevin

That is actually the one I have, with the 2-step. I wired it into the clutch pedal neutral safety switch. It's pretty neat to lay both the clutch and gas pedal to the floor and pull some fuel out at the limiter point and atmospheric pressure until the engine sounds good. I haven't used it after the first time out though because even at 2500rpm it was blowing the tires off the car. But I have since gotten better tires, so I should try it out again.

[dieselgeek]

If there are no objections I'm going to get a 6al-2. I like the built in 2 step.

Thanks,
Kevin

Objection!!

No need for a 2-step or rev limiter in the box, just get a 6A. Why? because the next thing you're going to do is load up the MS2-Extra firmware which has all the built in rev limiters you could ever want, Fuel, Spark, Fuel+spark with configurable cuts/sparks.

[TheSilverBuick]

I will admit I do have the MSD box's main limiter set really high and let the MS control the limiting, though I haven't tried out any of the launch control limiters with the MS (but there are many people successfully using them).