Spark plug wire routing

Spark plug wire routing

Eric Jensen
Eric Jensen

April 30th, 2006, 11:34 pm #1

I thought I remembered seeing a post recently about which spark plug wires should be separated. Darned if I can't seem to find it. Could someone please point me straight. Has anyone ever observed this on their engines? I have a fairly soft miss in my starboard 427 and I think it may caused by this.
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Paul
Paul

May 1st, 2006, 12:45 am #2

Hi Eric,

These are the plug wires you want to be sure don't touch #7 and 8), because you can get induction firing under certain conditions, and if this happens at wide open throttle it can really get your attention. You'll note cylinders 7 and 8 are right next to one another, and so are the plug wires, thus the danger. One plug is all powered up and ready to fire, and ooops, the spark jumps to the other wire and BANG, you get a pre-ignition.

As for the slight miss, this could possibly be the cause. I've recently been sensitized to plug wire resistance, and I've been checking my old wires with an ohm meter. Sure enough, some of them are really poor. Tim Toth recommends the spiral wire wound plug wires, which he claims have the lowest ohm resistance in the market. Low ohm resistance means all the spark energy gets to the plugs.

If you have conventional points and condenser, I'd suggest changing out to Pertronix electronic modules. It's the nicest thing you can do to a 427. Also, check the valve clearances, if you have them set too tight, it will run rough and you won't generate full power at higher rpm.

Here is the thread to the Pertronix Ignition info
http://www.network54.com/Forum/424840/m ... 1131313926

There are several such threads in the 427 section of the MASTER INDEX, which I believe you will find very helpful and interesting if you own a 427 (including a section on plug wires).

These are the main issues I'd go after for the "slight miss" symptoms. Good luck!

Regards, Paul





Here is where you can find plug wires #7 and #8








Last edited by FEfinaticP on July 9th, 2009, 2:22 pm, edited 1 time in total.
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Eric Jensen
Eric Jensen

May 1st, 2006, 3:24 pm #3

I'll check these next time I'm at the boat. Redid the plug wires recently, I've had the electronic ignition for several years and the just did the valve adjustment last Fall. I'm hopeful this could be the fix.
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Paul
Paul

May 1st, 2006, 4:05 pm #4

The 7 and 8 wires should not touch anywhere. There is such a magnetic field set up, that it can cause the other cylinder to fire.

The Small Block Chevy has the same problem with 5 and7 firing one after another and being adjacent. (Ford and Chevy identified their cylinders differently, Chevy put all odd numbers on one side, and all even numbers on the other, while Ford just numbered 1, 2, 3, 4 on one side, and 5, 6, 7, and 8 on the other side. Check the manual on that one to be sure you're looking at the proper cylinders).

EDIT COMMENT: I've just been informed by Mark Weller, who runs a pair of Q-series small block Chevrolet based motors, that the Q has an entirely different firing order. See his post that follows.

Regards, Paul


Last edited by FEfinaticP on May 19th, 2006, 5:06 pm, edited 1 time in total.
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Eric Jensen
Eric Jensen

May 9th, 2006, 3:00 am #5

Hi Eric,

These are the plug wires you want to be sure don't touch #7 and 8), because you can get induction firing under certain conditions, and if this happens at wide open throttle it can really get your attention. You'll note cylinders 7 and 8 are right next to one another, and so are the plug wires, thus the danger. One plug is all powered up and ready to fire, and ooops, the spark jumps to the other wire and BANG, you get a pre-ignition.

As for the slight miss, this could possibly be the cause. I've recently been sensitized to plug wire resistance, and I've been checking my old wires with an ohm meter. Sure enough, some of them are really poor. Tim Toth recommends the spiral wire wound plug wires, which he claims have the lowest ohm resistance in the market. Low ohm resistance means all the spark energy gets to the plugs.

If you have conventional points and condenser, I'd suggest changing out to Pertronix electronic modules. It's the nicest thing you can do to a 427. Also, check the valve clearances, if you have them set too tight, it will run rough and you won't generate full power at higher rpm.

Here is the thread to the Pertronix Ignition info
http://www.network54.com/Forum/424840/m ... 1131313926

There are several such threads in the 427 section of the MASTER INDEX, which I believe you will find very helpful and interesting if you own a 427 (including a section on plug wires).

These are the main issues I'd go after for the "slight miss" symptoms. Good luck!

Regards, Paul





Here is where you can find plug wires #7 and #8







I couldn't wait to check this when I got to the boat. The #7 and #8 were braided together like a twizzle stick. Took a couple of minutes to reroute the wires and voila! the stumble is gone. Thanks for the help. If only every project were this easy.
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Paul
Paul

May 9th, 2006, 11:12 am #6

Not all projects "are" that simple. The 427 is really not a complicated device, it's pretty well known by now, and the group here has "been there, done that" on many issues. If you have not already converted to Pertronix electronic ignition, consider doing so. It's the nicest thing you can do for your 427, because it essentially tosses the old style ignition points forever. Those points, by the way, are a MAJOR source of missing, hesitation, poor starting, etc., not only in the 427, but in any marine engine. The Pertronix uses a magnetic pickup, and there are many of us who have made the switch very successfully.

The Master Index has a section on Pertronix installation (it's in the 427 section of the Master Index).

I'm glad this one was simple for you, all the best!

Paul

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Bill M
Bill M

May 10th, 2006, 1:13 am #7

I couldn't wait to check this when I got to the boat. The #7 and #8 were braided together like a twizzle stick. Took a couple of minutes to reroute the wires and voila! the stumble is gone. Thanks for the help. If only every project were this easy.
Ha, bet we weren't the only ones this weekend messing around with spark plug wires . . . my 427's seemed to be running fine but I did find a tangled web of old orange autolite wires braided together, particularly #'s 7 and 8. I also puchased some new plastic iginition wire separators and did a nice job . . . getting set for my new wires when they arrive. It's my thirteenth season on this set, so time for an upgrade. Thanks again, guys!

Bill
Challenger
ChrisCraft Commander FlushDeck/Flybridge 41 Motoryacht
-powered proudly by 427 technology
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Dave Mehl
Dave Mehl

May 10th, 2006, 2:51 am #8

someone recently posted a thread, I think it was Tim Toth, about how to measure wires for ohm resistance to see if they were still up to spec. This weekend while you guys were un-tangling your 7 and 8 wires, I was measuring the ohm resistance, and I found some that were VERY much different than some of the others. These are the carbon core in fiberglass type of plug wires, which I'm immediately no longer fond of. Anything will work on the short term, but the metal plug wires are by far the best for long term reliability.

Regards, Dave
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Mark Weller
Mark Weller

May 10th, 2006, 3:43 am #9

Yes it was Tim who posted the thread about measuring resistance in your plug wires. He taught me that lesson well. Look into Splitfire Dual Mag wires Tim swears by them and now I do too. They are one of the best built wires I have ever seen dual Stainlees steel mag core and the resistance is very low, and they have an 8mm silicone jacket. Besides they are a nice color blue and will look good on the 427 Ford or a small block Chevy.
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Mark Weller
Mark Weller

May 19th, 2006, 4:50 pm #10

The 7 and 8 wires should not touch anywhere. There is such a magnetic field set up, that it can cause the other cylinder to fire.

The Small Block Chevy has the same problem with 5 and7 firing one after another and being adjacent. (Ford and Chevy identified their cylinders differently, Chevy put all odd numbers on one side, and all even numbers on the other, while Ford just numbered 1, 2, 3, 4 on one side, and 5, 6, 7, and 8 on the other side. Check the manual on that one to be sure you're looking at the proper cylinders).

EDIT COMMENT: I've just been informed by Mark Weller, who runs a pair of Q-series small block Chevrolet based motors, that the Q has an entirely different firing order. See his post that follows.

Regards, Paul

The Q motors have a different firing order you need to watch cylinders 2 & 4 they fire adjacent to each other on both motors the firing order on the LH rotation is 1-8-7-2-4-3-6-5 and on the RH rotation motor it is 1-5-6-3-4-2-7-8 so on both of the motors the firing order is an issue for the 2 & 4 cylinders, keep the wires apart and in keepers.
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