Previous Thread
Next Thread
Print Thread
Page 1 of 2 1 2
Where to get 12V key on inc cranking for Holley Sniper EFI #2763206
04/12/20 09:15 PM
04/12/20 09:15 PM
Joined: Feb 2006
Posts: 1,179
Canada
D
demon Offline OP
super stock
demon  Offline OP
super stock
D

Joined: Feb 2006
Posts: 1,179
Canada
A buddy is installing a Holley Sniper EFI on his 70 Charger. The car has the Mopar electronic ignition using a new engine harness that has the electronic harness built right in. The EFI requires 12 volt key on power for the computer. Needs to maintain constant 12 volt power while cranking. My thoughts were to tap into the hot side of the ballast resistor, but we found the voltage at the input of the ballast resistor drops off significantly while cranking. A friend suggested using this ballast resistor point to run a relay for direct battery voltage. Anyone have suggestions? One simple wire is holding us up.

Last edited by demon; 04/12/20 09:17 PM.
Re: Where to get 12V key on inc cranking for Holley Sniper EFI [Re: demon] #2763210
04/12/20 09:27 PM
04/12/20 09:27 PM
Joined: May 2019
Posts: 6,175
nowhere
S
Sniper Offline
master
Sniper  Offline
master
S

Joined: May 2019
Posts: 6,175
nowhere
the 12v side of the ballast should be within a tenth of a volt or so of the voltage at the battery + terminal, both referenced to the same ground. If it's not then you have issues, usually dirty or loose connections. A relay will probably band aid the problem but it may show up elsewhere. I've been known to use a relay to feed the ignition all the time anyway. The ignition switch used in out old stuff really was barely enough new, put some age and use on it and it starts showing it's issues.

Re: Where to get 12V key on inc cranking for Holley Sniper EFI [Re: demon] #2763240
04/13/20 12:47 AM
04/13/20 12:47 AM
Joined: Jan 2003
Posts: 30,947
Oregon
A
AndyF Offline
I Win
AndyF  Offline
I Win
A

Joined: Jan 2003
Posts: 30,947
Oregon
Hard to do if you're going to keep the ballast resister and the old Mopar distributor. My advice is to ditch the Mopar ignition system and put a Hyperspark distributor on there. Then you can get rid of the ballast resistor and tie IGN 1 and IGN 2 together. Your buddy will thank you later once he understands how much better the Sniper works when it can control timing. Installing a Sniper without timing control is a mistake.

Re: Where to get 12V key on inc cranking for Holley Sniper EFI [Re: AndyF] #2763929
04/14/20 04:46 PM
04/14/20 04:46 PM
Joined: Feb 2003
Posts: 8,659
A
Andrewh Offline
master
Andrewh  Offline
master
A

Joined: Feb 2003
Posts: 8,659
I think you will need 2 relays and tie them together.
I think if you try and use 1 relay you will bridge over the ballast and put 12 volts all the time to the coil.
So you need one from the crank side of the ballast for 12 volts crank to 1 relay.
Then a second from the 12 volt feed to the ballast in run.
Both outputs tie together after the relays to feed the efi computer.

Re: Where to get 12V key on inc cranking for Holley Sniper EFI [Re: Andrewh] #2763945
04/14/20 05:40 PM
04/14/20 05:40 PM
Joined: Apr 2005
Posts: 4,910
new berlin wisconsin
M
Mr T2U Offline
master
Mr T2U  Offline
master
M

Joined: Apr 2005
Posts: 4,910
new berlin wisconsin
i don't know the exact details of your voltage needs.
when i installed a MSD in my 72 road runner. i just attached both the, i think, lt brown and blue wires together at the ballast resistor. one wire has 12V with key on but goes away when you turn the key start position. the other one has no volts at key on but full voltage when you turn the key start. hook both together and you have power at both key on and key start.
this worked for my MSD, don't know if it will work for you.


perception is 90% of reality
Re: Where to get 12V key on inc cranking for Holley Sniper EFI [Re: Mr T2U] #2763954
04/14/20 06:25 PM
04/14/20 06:25 PM
Joined: May 2019
Posts: 6,175
nowhere
S
Sniper Offline
master
Sniper  Offline
master
S

Joined: May 2019
Posts: 6,175
nowhere
MSD doesn't require a ballast, the OP is, I think, keeping the stock ignition which does require a ballast.

Re: Where to get 12V key on inc cranking for Holley Sniper EFI [Re: Sniper] #2763973
04/14/20 07:34 PM
04/14/20 07:34 PM
Joined: May 2005
Posts: 4,681
Florida
BDW Offline
master
BDW  Offline
master

Joined: May 2005
Posts: 4,681
Florida
Been covered before, for ignition with ballast, place a diode across the ballast.
That’s the way mine’s set-up for 2 yrs with FiTech and Mopar electronic distributor.

[Linked Image]

Last edited by BDW; 04/14/20 08:01 PM.
Re: Where to get 12V key on inc cranking for Holley Sniper EFI [Re: BDW] #2763995
04/14/20 08:51 PM
04/14/20 08:51 PM
Joined: Mar 2006
Posts: 9,791
MI, usa
dvw Online content
master
dvw  Online Content
master

Joined: Mar 2006
Posts: 9,791
MI, usa
Tie the brown and the dark blue together from the old ballast resistor. Blue is hot in run only. Brown is hot in crank only.
Doug

Re: Where to get 12V key on inc cranking for Holley Sniper EFI [Re: dvw] #2764084
04/15/20 06:26 AM
04/15/20 06:26 AM
Joined: Aug 2007
Posts: 6,089
Valencia, España
NachoRT74 Offline
master
NachoRT74  Offline
master

Joined: Aug 2007
Posts: 6,089
Valencia, España
Keeping the stock ignition system, the diode over the ballast terminals would be the correct setup to keep the coil safe in RUN just like it should be with low voltage while allowing full 12 volts when cranking ( from brown to blue wire ) to the EFI being spliced into the Run circuit as must be.

MSD ignition requieres a ballast bypass just on RTR distributors because that's the source for them. MSD ECU modules don't need the ballast bypass because the wire to coil ( with ballast still there ) used for this works just as a remote on signal where the ballast signal is enough to keep it on, not for the source. The load for the module runs in a diff wire.

Need to say, once the diode is set, the ballast wires ( brown end and blue end ) must be connected AALWAYS on that way, being a resistor it doesn't matter which wire is conected on what prong, but with a parallel diode, it must be conected on the correct way. EXCEPT if you link the diode between wires instead at the ballast prongs, which it won't care where you connect the ballast wires just like originally is.


With a Charger born in Chrysler assembly plant in Valencia, Venezuela
Re: Where to get 12V key on inc cranking for Holley Sniper EFI [Re: demon] #2764145
04/15/20 09:30 AM
04/15/20 09:30 AM
Joined: Jan 2008
Posts: 2,592
None
71rm23 Offline
master
71rm23  Offline
master

Joined: Jan 2008
Posts: 2,592
None
Something on the same here with the OP and not to highjack his thread. I'm thinking of doing the same thing to my car. The only difference is that I have a FBO ECU and it says I don't need the ballast as well. In fact, I'm suppose to use a jumper where the brown and blue is and just stow those two. The FBO ECU needs all juice going to it. My car is a 71 but converted to electronic ignition. I think it will work by doing what BDW said, if I'm understanding correctly. The white box in the picture is what I have

thumbnail_20170204_132015_resized.jpg
Re: Where to get 12V key on inc cranking for Holley Sniper EFI [Re: 71rm23] #2764149
04/15/20 09:33 AM
04/15/20 09:33 AM
Joined: Feb 2003
Posts: 8,659
A
Andrewh Offline
master
Andrewh  Offline
master
A

Joined: Feb 2003
Posts: 8,659
The diaode is another way to do it. but the 2 relay's will isolate the circuits too.
While a diaode might be the "correct" way to do it, if you don't have one the relay's are probably a fast way to get going.

Re: Where to get 12V key on inc cranking for Holley Sniper EFI [Re: Andrewh] #2764257
04/15/20 02:06 PM
04/15/20 02:06 PM
Joined: Aug 2007
Posts: 6,089
Valencia, España
NachoRT74 Offline
master
NachoRT74  Offline
master

Joined: Aug 2007
Posts: 6,089
Valencia, España
FBO box doesn't need ballast ( per their instructions ) is a diff deal. The diode solution is for the stock ignition which requires/includes ballast on the game

The relay could be an option DEPENDING on the voltage what the relay operates, BUT also requires more wiring involved to make it work. Remember ballast change the operating voltage range with temperature and load going throught so could be switching on and off constantly. Never have made it but just IT COULD happen


The diode is the easier, no need for extra sources/wiring, just jump out both circuits with it... but correctly done, to keep the ign 2 circuit still isolated from the Ign1 while car is in run, which is the deal on this to keep the coil on the ballast operating range, but just jump out the ballast for the ign 1 circuit while cranking

Now, the value for the diode! I can't tell which one could be the best. I'm not in those numbers

Last edited by NachoRT74; 04/15/20 02:51 PM.

With a Charger born in Chrysler assembly plant in Valencia, Venezuela
Re: Where to get 12V key on inc cranking for Holley Sniper EFI [Re: NachoRT74] #2764277
04/15/20 03:06 PM
04/15/20 03:06 PM
Joined: Feb 2003
Posts: 8,659
A
Andrewh Offline
master
Andrewh  Offline
master
A

Joined: Feb 2003
Posts: 8,659
voltage should still be 12 volts.
you tap crank voltage off the after ballast circuit. Tap run voltage from before the ballast circuit and you get 12 volts for both. so it "bypasses" the ballast all together for the relay's.

Re: Where to get 12V key on inc cranking for Holley Sniper EFI [Re: Andrewh] #2764284
04/15/20 03:23 PM
04/15/20 03:23 PM
Joined: Aug 2007
Posts: 6,089
Valencia, España
NachoRT74 Offline
master
NachoRT74  Offline
master

Joined: Aug 2007
Posts: 6,089
Valencia, España
I got what you meant

30- input from blue circuit
87-output to blue circuit
87a ( if 5 pins )-empty
86-trigger from brown circuit
85 ground

but still, a cleaner way just the diode LOL. And if relay gets activated by the low level ballast ouput, could remain activated. Nothing wrong really thought, but maybe switching on and off constantly with Ballast voltage variations. ( just thinking out loud )

Last edited by NachoRT74; 04/15/20 03:24 PM.

With a Charger born in Chrysler assembly plant in Valencia, Venezuela
Re: Where to get 12V key on inc cranking for Holley Sniper EFI [Re: Andrewh] #2764285
04/15/20 03:24 PM
04/15/20 03:24 PM
Joined: May 2005
Posts: 4,681
Florida
BDW Offline
master
BDW  Offline
master

Joined: May 2005
Posts: 4,681
Florida
Diodes used for solar panel have high current capability (although probably not needed) but more importantly low voltage drop

https://www.ebay.com/itm/382772093682

Re: Where to get 12V key on inc cranking for Holley Sniper EFI [Re: BDW] #2764410
04/15/20 08:05 PM
04/15/20 08:05 PM
Joined: Jan 2003
Posts: 15,197
Omaha Ne
T
TJP Offline
I Live Here
TJP  Offline
I Live Here
T

Joined: Jan 2003
Posts: 15,197
Omaha Ne
iagree

Re: Where to get 12V key on inc cranking for Holley Sniper EFI [Re: demon] #2764506
04/16/20 08:25 AM
04/16/20 08:25 AM
Joined: Feb 2006
Posts: 1,179
Canada
D
demon Offline OP
super stock
demon  Offline OP
super stock
D

Joined: Feb 2006
Posts: 1,179
Canada
I appreciate all the input and suggestions. But, I am more confused than when I started.
Is it really this complicated to find a 12 volt power source?
We just need to hook up one wire to make this car run.
There must be dozens, if not hundreds of Mopars with the Sniper EFI or some others EFI systems installed.
Where is everyone hooking up the power wire?

Re: Where to get 12V key on inc cranking for Holley Sniper EFI [Re: demon] #2764519
04/16/20 09:17 AM
04/16/20 09:17 AM
Joined: Mar 2006
Posts: 9,791
MI, usa
dvw Online content
master
dvw  Online Content
master

Joined: Mar 2006
Posts: 9,791
MI, usa
Like I said. Tie the dk blue and brown together. That will provide you with battery voltage running and cranking. Nothing more. nothing less. The ballast purpose was never to protect the coil. It was to protect points or old ECUs. If Your ECU doesn't need a ballast it doesn't need diodes relays or anything else.
Doug

Re: Where to get 12V key on inc cranking for Holley Sniper EFI [Re: dvw] #2764526
04/16/20 09:54 AM
04/16/20 09:54 AM
Joined: Feb 2003
Posts: 8,659
A
Andrewh Offline
master
Andrewh  Offline
master
A

Joined: Feb 2003
Posts: 8,659
There are multiple places that you could get key on power.
but only 1 for cranking power.

as stated if you need the ballast resistor, you have to do something to tie the cranking power to key on power so the efi computer has power during crank and run.
You do not need to use ballast power for key on if you don't want to.
People generally use those because they are close together when wiring.
most efi setups don't use the original ignition system, so they generally don't need the ballast. Since they take it out, fastest way is to tie those two wires together and viola you power your efi key on and cranking.

Re: Where to get 12V key on inc cranking for Holley Sniper EFI [Re: AndyF] #2764543
04/16/20 10:31 AM
04/16/20 10:31 AM
Joined: Feb 2013
Posts: 140
Missouri
R
randavis Offline
member
randavis  Offline
member
R

Joined: Feb 2013
Posts: 140
Missouri
Originally Posted by AndyF
Hard to do if you're going to keep the ballast resister and the old Mopar distributor. My advice is to ditch the Mopar ignition system and put a Hyperspark distributor on there. Then you can get rid of the ballast resistor and tie IGN 1 and IGN 2 together. Your buddy will thank you later once he understands how much better the Sniper works when it can control timing. Installing a Sniper without timing control is a mistake.


I agree with Andy. I originally tried to use the stock dizzy and an old MSD 5C with my setup. After fighting emi for a while, I bought the HyperSpark and and the 6EFI cd box and most of my problems went away. I'm still adjusting the spark and fuel tables, but the car runs so much better.


74 Challenger, bought it new. In 1978 I replaced the original 318 with a 446 and 727. Mild cam, Jardine headers, and Holley Sniper EFI.
New engine! 511" RB, Edelbrock Performer RPM heads, Eagle rotating assy, Comp hyd roller cam, Doug's 2" headers.
Page 1 of 2 1 2






Powered by UBB.threads™ PHP Forum Software 7.7.1