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#1064610 - 12/29/19 05:49 PM Need to find hot 12v while cranking!!  
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lousnut Offline
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E. Longmeadow MA
I'm helping install a Sniper EFI on a friends 87 SS and so far it's going ok but now we're trying to find 12 v hot while cranking and are told in the instructions not to use the starter location, can anyone out there help with a location.
Is there a spot on the fuse panel?? or where else? thanks, LouSnut

#1064612 - 12/29/19 10:22 PM Re: Need to find hot 12v while cranking!! [Re: lousnut]  
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SSLance Offline
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I used the pink wire that powered the distributor to switch a relay that provided direct battery power to my Holley. Try to use as many relays as you can with that setup to avoid RFI issues. What distributor are you using?


Lance
1985 Monte Carlo SS Street Car
#1064620 - 12/30/19 02:57 PM Re: Need to find hot 12v while cranking!! [Re: SSLance]  
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lousnut Offline
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E. Longmeadow MA
The stock distributor!

#1064621 - 12/30/19 03:07 PM Re: Need to find hot 12v while cranking!! [Re: lousnut]  
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SSLance Offline
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Well, that isn't going to work...for a lot of different reasons.

The stock distributor needs the stock ECM to control the timing thru it. You'll need to find another way to control timing in order for it to even start.

I used a small cap HEI distributor and the Holley EFI software and ECU to control the timing in my car and it works awesome. That is probably the most economical path you should take. Ask away if you have more questions...happy to help out if I can.


Lance
1985 Monte Carlo SS Street Car
#1064630 - 12/31/19 11:15 PM Re: Need to find hot 12v while cranking!! [Re: SSLance]  
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lousnut Offline
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E. Longmeadow MA
Thanks Lance, and a Happy new year to you. I'll have more ?s as we proceed. My friend say's how about a vacuum controlled dist. taking vac off the EFI?? No thinking it over, that would be points and who wants points.

Last edited by lousnut; 12/31/19 11:18 PM.
#1064635 - 01/01/20 04:04 PM Re: Need to find hot 12v while cranking!! [Re: lousnut]  
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SSLance Offline
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In my opinion...why would someone go thru the trouble of converting to EFI and not let the ECU control timing as well?

It all works hand in hand, you really won't realize the full advantage of EFI without timing control. This is not something that anyone should pinch pennies on. Takeoff small cap HEI distributors should be easily found or even a brand new in box MSD 8366 is only about $300. Either one will provide WAY more in performance and drivability than the Sniper itself will with an analog distributor controlling timing.


Lance
1985 Monte Carlo SS Street Car
#1064640 - 01/02/20 02:41 AM Re: Need to find hot 12v while cranking!! [Re: lousnut]  
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BadSS Offline
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Pearl, MS, 39208
Seems like they converted in 87 to the small cap HEI (???). If so, like Lance said you can use the small cap HEI distributor for system timing control.

Unplug the connector for the trigger wires
[Linked Image]

Take out the control module and make something like in the picture to seal off the distributor cap.
[Linked Image]

The picture shows him holding the MSD 8861 module bypass that would plug into the trigger wires.
https://www.summitracing.com/parts/msd-8861
[Linked Image]

If brave enough and the Sniper's wiring is long enough, you could cut off the Sniper’s plug and put on some male spade connectors – I’d splurge.

#1064641 - 01/02/20 02:17 PM Re: Need to find hot 12v while cranking!! [Re: BadSS]  
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lousnut Offline
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It is a small cap dist. I will look into what you suggest.Thanks to you BadSS and Lance for taking the time to answer w/ help.

#1064645 - 01/02/20 03:05 PM Re: Need to find hot 12v while cranking!! [Re: lousnut]  
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SSLance Offline
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That is pretty freaking slick...


Lance
1985 Monte Carlo SS Street Car
#1064648 - 01/02/20 11:14 PM Re: Need to find hot 12v while cranking!! [Re: lousnut]  
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lousnut Offline
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E. Longmeadow MA
are you saying that, that MSD part will plug directly into the sniper wiring plug?? In another question will the stock ECM still control the Ignition if I do nothing at all even after unplugging all the elect. and vac froom the carb, iin other words does any of that have any effect on the timing? thanks, Lou

#1064651 - 01/03/20 03:33 AM Re: Need to find hot 12v while cranking!! [Re: lousnut]  
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BadSS Offline
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I was thinking the MSD plug and the Sniper plug were the same but from the pictures I could find on the internet it doesn't appear to be. Looks like the MSD distributor for the Sniper unit uses a different plug than all the rest of the MSD distributors. That picture of him holding the "typical" MSD plug should give you a good idea if it'll plug up or not - I'm thinking not right now. .

When you unplug all the computer wiring from the carb it puts the stock ECM into limp home mode. It'll crank and run but the timing will only be what ever you have the base timing set to. So, no it won't work stand alone.

Lance, what did you use for the connection to the small cap distributor?

#1064653 - 01/03/20 03:09 PM Re: Need to find hot 12v while cranking!! [Re: lousnut]  
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SSLance Offline
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I used this Holley harness to adapt the Small Cap HEI to the Holley Terminator harness.

https://www.holley.com/products/ignition/ignition_harnesses/parts/558-304

[Linked Image]

The Sniper harness may be different and need a different adapter harness, I'm not sure.

This is the distributor I used.

https://www.holley.com/products/ignition/distributors/chevrolet/ready_to_run_distributors/parts/8366

[Linked Image]

Watch this idle video to see how the Holley ECU controls timing and fuel hundreds of times per second for maximum performance. It is amazing to see what it can do once dialed in. Personally, I wouldn't even bother going through the trouble of converting to EFI without doing the whole system. It'll never work well if you try to just bolt the Sniper on in place of the carb.

https://youtu.be/JP8RA43M8Ps


Lance
1985 Monte Carlo SS Street Car
#1064654 - 01/03/20 03:15 PM Re: Need to find hot 12v while cranking!! [Re: lousnut]  
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SSLance Offline
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Originally Posted by lousnut
will the stock ECM still control the Ignition if I do nothing at all even after unplugging all the elect. and vac froom the carb, iin other words does any of that have any effect on the timing? thanks, Lou


From my understanding, if you do not have 100% of the stock ECM parts and pieces hooked up and functioning, none of it will operate properly.

OEM and aftermarket type engine control systems are all designed to all work together as a package. They read information from all of the sensors (Manifold Air Pressure, Coolant Temp, Throttle position, RPM, O2, etc) and make corrections to fuel delivery and timing in real time to maximize efficiency. If you try to use only half of the system (either system) it just won't work properly.


Lance
1985 Monte Carlo SS Street Car
#1064660 - 01/04/20 04:06 PM Re: Need to find hot 12v while cranking!! [Re: lousnut]  
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lousnut Offline
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E. Longmeadow MA
Thanks again to you both. I'm going to call and or E mail holley and check on that harness Lance showed, it or some similar might be the answer. My friend would like to keep this as simple as possible as he's just looking for drive ability and easy starting. The existing carb drains or evaporates creating long cranking till start-up. Lou

#1064664 - 01/05/20 02:04 AM Re: Need to find hot 12v while cranking!! [Re: lousnut]  
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BadSS Offline
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Originally Posted by lousnut
The existing carb drains or evaporates creating long cranking till start-up. Lou


That's pretty common - usually it's the fuel well plugs leaking. Don't trash the carb, it's a pretty easy fix.

https://www.hotrod.com/articles/hppp-1107-home-remedy-quadrajet-carburetor/

#1064681 - 01/06/20 04:14 PM Re: Need to find hot 12v while cranking!! [Re: lousnut]  
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lousnut Offline
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E. Longmeadow MA
E mailed Holley and go a quick answer, the small cap is not compatible with Sniper EFI. The dist. Lance showed is similar to the one to use, on sale now 249.00 w/ box and harness. Thanks Guys Lou

Last edited by lousnut; 01/06/20 04:17 PM.
#1064988 - 02/02/20 11:16 PM Re: Need to find hot 12v while cranking!! [Re: lousnut]  
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lousnut Offline
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E. Longmeadow MA
Still plugging away on this EFI install, what a xxxx and a royal pain in the xxxx . Not as simple as the ad would make you think. It could be simple on a 50s car where the electronics and vacuum BS was missing, but our cars, forget it.. I can only get 1 or 2 hours a day once or twice a week on this project so it's going slowly.
I'm still not sure where to get 12 V power that's key controlled and hot while the switch is in the cranking position too..I don't want to get into the ignition switch proper and am hoping there is a spot on the fuse panel that's what I need. Does anybody out there know if there is??? I would be eternally great full if someone could help, Thanks LouSnut

#1064995 - 02/03/20 03:40 PM Re: Need to find hot 12v while cranking!! [Re: SSLance]  
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SSLance Offline
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Originally Posted by SSLance
I used the pink wire that powered the distributor to switch a relay that provided direct battery power to my Holley. Try to use as many relays as you can with that setup to avoid RFI issues.


Keep it simple...


Lance
1985 Monte Carlo SS Street Car
#1064999 - 02/03/20 08:13 PM Re: Need to find hot 12v while cranking!! [Re: lousnut]  
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lousnut Offline
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Thanks again for the input Lance, I looked at that suggestion but it seems to me I'd be getting battery power even after key off. I;m not an electrical genius so I may not be thinking it right Lou
Lance, I think I now understand what your telling me, I've been on Google and several comments on the pink wire you were referring to and now I understand. Thanks again

Last edited by lousnut; 02/03/20 08:59 PM. Reason: new info
#1065076 - 02/09/20 07:32 PM Re: Need to find hot 12v while cranking!! [Re: lousnut]  
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lousnut Offline
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E. Longmeadow MA
Used a 4 pole relay and took power from the pink wire and everything is looking good, just need to finish up the O2 install and I may be able to start this thing. Thanks Lance and BadSS for the help. Lou


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