MSD, SPAL's, and EMI?
Thread Starter
Burning Brakes
Joined: Nov 2000
Posts: 948
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From: Johnston Iowa
MSD, SPAL's, and EMI?
Just a question for those of you that are running MSD setups (Distributor, Ignition Box, & Coil) and dual Spal's or other electronics. Have you every ran into any kind of Electro Magnetic Interference (EMI) problems with your MSD setup?
At the end of the driving season in my area last fall I noticed I was starting to get a high rpm miss. I see quite a few people on MSD's Tech forum that have ran into problems with EMI messing with their MSD configurations. Just curious about the corvette people that are running MSD setups and what you have done to avoid it or if you have even had a problem with it. I have a number of things I'm going to try once it gets nice here again but just thought I would check with you guys too in the mean time
Thanks.
At the end of the driving season in my area last fall I noticed I was starting to get a high rpm miss. I see quite a few people on MSD's Tech forum that have ran into problems with EMI messing with their MSD configurations. Just curious about the corvette people that are running MSD setups and what you have done to avoid it or if you have even had a problem with it. I have a number of things I'm going to try once it gets nice here again but just thought I would check with you guys too in the mean time
Thanks.
Race Director
Joined: Apr 2000
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
It is not good to run my LM-1 wideband wires anywhere near it. EMI usually affects other devices, it would be unusual for the device emitting EMI to be adversly affected by it's own EMI however it could happen I guess. 
Sorry just re-read your post and I do see where you are talking about other devices like Spal electric fans. I have electric fans and have never noticed anything unusual happening with my MSD box or ignition
I was the desingnated EMI guy at the last place I worked and ferrites on cables are hands donw the best EMI suppressant. I actually have them on my LM-1 cables and my MSD igintion cables. They are the snap on type that go around a wire and come in different sizes for different frequency ranges If you think it's the fans you can put them on the wires to the fans
Sorry just re-read your post and I do see where you are talking about other devices like Spal electric fans. I have electric fans and have never noticed anything unusual happening with my MSD box or ignition
I was the desingnated EMI guy at the last place I worked and ferrites on cables are hands donw the best EMI suppressant. I actually have them on my LM-1 cables and my MSD igintion cables. They are the snap on type that go around a wire and come in different sizes for different frequency ranges If you think it's the fans you can put them on the wires to the fans
Last edited by MotorHead; Feb 24, 2007 at 05:05 PM.
Thread Starter
Burning Brakes
Joined: Nov 2000
Posts: 948
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From: Johnston Iowa
Interesting! I never even thought about ferrites.
That maybe something I may need to look into.
Like you said they are about as easy to install as it gets.
Figuring the frequency range I may need is another thing.
Thanks for the information.
That maybe something I may need to look into.
Like you said they are about as easy to install as it gets.
Figuring the frequency range I may need is another thing.
Thanks for the information.
Race Director
Joined: Apr 2000
Posts: 17,676
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
I just put different sizes on, no way you are going to figure out the frequency without a spectrum analyzer. You want to put them as close as you can to the piece of equipment you want to protect, and the same goes for the emitting equipment.
The cables are the biggest emitter as well as the biggest conductive part on the equipment. In other words you put a ferrite(s) on the wires near the Spal fans as well as the MSD box
You can try metal shielding around the box, grounded to the frame but in my experience this has limited effect, do the cables first
The cables are the biggest emitter as well as the biggest conductive part on the equipment. In other words you put a ferrite(s) on the wires near the Spal fans as well as the MSD box
You can try metal shielding around the box, grounded to the frame but in my experience this has limited effect, do the cables first
Advanced
Joined: Sep 2006
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From: Modesto CA.
i have had a lot trouble with MSD and EMI.. after many calls to MSD one of the tec's told me to rap my 8860 harness with foil.... it will protect it from EMI.... i've got $850.00 in this MSD PRO-BILLET MASTER BLASTER 6AL TV ANTENNA!..... this setup hit on all the wrong cyclinders and singled out one or two for no good reason... i found in a MSD tec sheet that they offer pn# 8862 a shielded harness to help with EMI..... 1969 # matching 427, bal-blue print,port and polish, $$$.. this MSD system is not for my fiberglass car,.. i think it's best in a steel body car, that will help protect it from EMI.... with the pn#8862 in, at night with lights on after 45 min. of driving the car would start missing..... i'm sure others have had good luck with MSD.... i'm not one......
Race Director
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From: Athens GA
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Melting Slicks
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From: St. Charles Mo
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Also a good power ground layout is important. I would be surprised if the fans are causing significant radiated EMI. More likely conductive. I source the power for the fans off the alt. The MSD, EFI computers, etc. should be sourced off the battery with their own solid ground returns. The major source of radiated EMI is the high voltage ignition wires, coil and spark. Be sure hall effect and VR pickup wires from the distributor are shielded, with only one side of the shield grounded. Usually the source side. Also, keep them as short as possible.Bullshark
Last edited by Bullshark; Feb 26, 2007 at 08:16 AM.
Advanced
Joined: Sep 2006
Posts: 94
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From: Modesto CA.
i think that MSD should have this EMI problem in check and i think they do..... but my name is not John Force or do i drive for Home Depot..... if i did i would get a better reply than "rap in foil".......... the system looks first class!!!... the help from MSD is not...
Thread Starter
Burning Brakes
Joined: Nov 2000
Posts: 948
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From: Johnston Iowa
I'm not saying this is my problem I was just curious to know if others have seen this before. As far as my electrical setup I'm running a 140AMP Power Master Alternator wired off Mark Harmons (Madd Electrical) setup. I run a thick wire to distribution point and then from that dist point I connect all of my high current draw items. Again I have a number of things to test once it gets nice I was just doing a little research. I tested this last year and do maintain 14.4 volts at the dist point under high RPM's but I'm going to go back and verify this again and verify the volts at the battery under high RPM's too. My MSD setup worked fine prior to me noticing this at the end of last year so I sure its something simple. I hope!!!!
Race Director
Joined: Nov 2006
Posts: 19,445
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From: Athens GA
St. Jude Donor '12-'13, '15- '16-'17-'18-'19, '21
I'm not saying this is my problem I was just curious to know if others have seen this before. As far as my electrical setup I'm running a 140AMP Power Master Alternator wired off Mark Harmons (Madd Electrical) setup. I run a thick wire to distribution point and then from that dist point I connect all of my high current draw items. Again I have a number of things to test once it gets nice I was just doing a little research. I tested this last year and do maintain 14.4 volts at the dist point under high RPM's but I'm going to go back and verify this again and verify the volts at the battery under high RPM's too. My MSD setup worked fine prior to me noticing this at the end of last year so I sure its something simple. I hope!!!!
And keep us posted as some of us may run into same problem down the road.
