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Old 09-09-2013, 05:37 PM
Bronte Bronte is offline
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Default Connection of MSD ignition to Holley EFI

The car was a carb setup with an msd ignition. MSD coil, digital 6 plus, msd distributor.

I had a holley hp efi system replace the carb setup, but i cant get the car to turn over. I keep getting RPM stall. If I touch the tach output on the digital 6, the rpm shows for a second then cuts out back to stall.

holley stated that without tach output reaching their ignition trigger, it wont ever allow the car to start.

i just got the digital 6 back from msd after they verified it is ok.

any thoughts? the setup worked without issue when carbed.

One thought crossed my mind, but i don't know if it makes sense. can the distributor for a carb application be used in an efi application?

(I can't find the model of distributor unless I take it out. I am not mechanically inclined and don't want to cause more damage.)
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Old 09-09-2013, 11:12 PM
Joker11 Joker11 is offline
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Yes, you can use a distributor on carb or efi. Especially an MSD.
I am running a Mallory distributor on my truck and just installed an MSD 6A.
It works great. Tomorrow I get my Edelbrock EFI.
If you are using a mechanical advance and vacuum advance, your timing curve will be controlled by your distributor. If the Holley has ignition controls, which I have no knowledge of, you will have to lock out your distributor of both mechanical and vacuum advance. That makes your distributor a signal generator and spark distributor only. Meaning that it generates the signal but has no advance curve characteristics. That would all be coming from your EFI controller.

The Edelbrock does not control ignition so I am keeping my Mallory distributor and MSD 6A setup. I am happy with it. Why change a good thing?

But going back to Holley, you need to figure out why you don't have a signal to your EFI. with the A6, there is a gray wire that outputs to the tach. It will work with SOME tachometers and not others. In the case where it won't, we have to buy a tach adapter. You may need one in your case. I am not sure of your setup.

MSD tech support is pretty good at helping out with these wiring issues. Edelbrock is as well. I hope for you that Holley is too!

Note that MSD does not tell you on the package that you have to use an inductive timing light to check timing. I don't know if you have discovered that part or not. The multiple spark feature goofs up the computer timing lights unless they have a feature to sense the MSD. I did not know that until I tried to time my engine. This is probably why MSD uses the gray wire for a tach output.



Good luck, let us know how it goes and how you fix it.

Last edited by Joker11; 09-09-2013 at 11:16 PM. Reason: add timing light info.
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Old 09-10-2013, 08:40 AM
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msdtech1955 msdtech1955 is offline
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is the distributor a 2 or 3 wire connection?
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Old 09-10-2013, 08:42 AM
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msdtech1955 msdtech1955 is offline
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is there 12 volts on the thin red wire while cranking ?
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Old 09-10-2013, 08:43 AM
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msdtech1955 msdtech1955 is offline
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Quote:
Originally Posted by Joker11 View Post
Yes, you can use a distributor on carb or efi. Especially an MSD.
I am running a Mallory distributor on my truck and just installed an MSD 6A.
It works great. Tomorrow I get my Edelbrock EFI.
If you are using a mechanical advance and vacuum advance, your timing curve will be controlled by your distributor. If the Holley has ignition controls, which I have no knowledge of, you will have to lock out your distributor of both mechanical and vacuum advance. That makes your distributor a signal generator and spark distributor only. Meaning that it generates the signal but has no advance curve characteristics. That would all be coming from your EFI controller.

The Edelbrock does not control ignition so I am keeping my Mallory distributor and MSD 6A setup. I am happy with it. Why change a good thing?

But going back to Holley, you need to figure out why you don't have a signal to your EFI. with the A6, there is a gray wire that outputs to the tach. It will work with SOME tachometers and not others. In the case where it won't, we have to buy a tach adapter. You may need one in your case. I am not sure of your setup.

MSD tech support is pretty good at helping out with these wiring issues. Edelbrock is as well. I hope for you that Holley is too!

Note that MSD does not tell you on the package that you have to use an inductive timing light to check timing. I don't know if you have discovered that part or not. The multiple spark feature goofs up the computer timing lights unless they have a feature to sense the MSD. I did not know that until I tried to time my engine. This is probably why MSD uses the gray wire for a tach output.



Good luck, let us know how it goes and how you fix it.
http://www.setyourtiming.com/
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  #6  
Old 09-11-2013, 07:13 PM
Bronte Bronte is offline
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I apologize for the delay in response.

The distributor is a 2 wire unit.

I will need to verify the 12v on the red wire this weekend.

Out of curiosity, is it possible to use the distributor to generate tach output? My reason for asking is that it is physically closer to the Holley wiring harness. (Although I don't know if 3 feet of wire can cause that big of a drop in signal.)
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Old 09-12-2013, 12:30 PM
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msdtech1955 msdtech1955 is offline
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Quote:
Out of curiosity, is it possible to use the distributor to generate tach output? My reason for asking is that it is physically closer to the Holley wiring harness. (Although I don't know if 3 feet of wire can cause that big of a drop in signal.)

unfortunately not...
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