: Custom made 8.5mm MSD spark plug wires



Edahall
02-20-08, 12:32 PM
My 93 Northstar has been running poorly and I partially fixed the problem by replacing a coil but it continues to stumble at low RPM's and high throttle positions. I opened the hood last night and saw sparks emitting from the plug wires. It looks like it's time for a new set of spark plugs and wires. I have made my own custom wires using the OE boots and MSD wire that you buy in a large roll for my 88 Eldorado 4.5L. I want to do the same with this engine. I think MSD wires are higher quality and it would be less than 1/2 the price of a new set of ready made AC Delco's.

My question is if it's possible to remove the old wire from the long boot that sticks down the head. I want to reuse these boots.

Submariner409
02-20-08, 04:03 PM
Unless the old wire/boot combo is 8.5mm, you're out of luck, and you need the insulation those boots furnish.

Many, many posts here about sticking to ACDelco wire.

We use ACCEL, Taylor, or MSD equipment on our GM big block boat engines, not on Cadillac N* engines.

Edahall
02-20-08, 05:31 PM
I was able to make the boots stretch onto the larger wire on my Cadillac 4.5 a and I'm hoping to do the same with this car however the long boot that fits down the valve cover might be an issue. I doubt anyone has ever fitted MSD wires on their N* so I might be the first. You can't even buy a set of MSD pre-made wires for this car.

Submariner409
02-20-08, 05:35 PM
Which is why everyone in here recommends the OEM ACDelco set.

dkozloski
02-20-08, 06:30 PM
Smokey Yunick swore by Packard 440 sparkplug wire forty years ago. It's alive and well in the present day DelCo kits. If there was ever a proven automotive product that is it.

Submariner409
02-20-08, 06:58 PM
Old Packard 440 is good stuff, but it's unshielded stranded copper wire and plays hell with radios and today's data transmission lines. I think it's illegal, due to radiated EMI, except for pure race use.

I have a 3 foot loop of it, from my MG days, hanging on the garage wall for nostalgia.

It may still be available in the big PAW catalog.

If the wire in a Delco kit is labelled 440, it has to be modern shielded stuff......Google "packard 440 wire" and the number comes up as stranded copper wire.

fubar569
02-21-08, 02:59 AM
i attempted to disassemble the boots and this is that i found:

it takes a razor and a steady hand...carefully cut down one of the lines from the mold on the boot.

once this is done it should be fairly easy to remove old wire, but NOTE EXACTLY WHERE the spark plug end SITS IN THE GROOVES. mark it to be safe...

this is as far as i got...i had concerns about being about to reseal the boot. I havent found anything suitable for the job that would be as flexible as the original and allow for proper insulation and shielding without leakage.

i bought an OEM set...and quite honestly, it really is the way to go...

the only way you'd ever need them is if you build a serious boost/bottle motor for a dragster/sandrail and even then stock will probably be adequate.

for those who insist on "performance" wires, magnecor does make a set for the northstar. expect to pay dearly...

Edahall
02-21-08, 11:55 AM
fubar, thanks for your reply.

I was hoping to be able to remove the wire without slicing the boot. I know that it can be done on the smaller boots because I've done it before. Hmmm. Maybe I'll go to the junkyard and try to find used spark plug wire that I can practice on.

fubar569
02-21-08, 04:02 PM
I was hoping to be able to remove the wire without slicing the boot.

i tried every conceivable way and it's not possible. even if you did, you'd likely never be able to feed the wire through the boot as required and into the grooves that lock in the spark plug clip...the boots themselves should be able to hold an 8.5mm wire with little/no modification inside. the issue is getting the wire in and then sealing the boot off again.

Edahall
02-21-08, 05:23 PM
Fubar, I think you answered my question.

I have ways to feed the new wire through the boot but I must first be able to get the old wire out. If that's not possible, then it's a no go.

fubar569
02-21-08, 06:07 PM
Fubar, I think you answered my question.

I have ways to feed the new wire through the boot but I must first be able to get the old wire out. If that's not possible, then it's a no go.

perhaps you are more gifted than i am...this being possible, try it on junk wires like you planned on. i could not get a clean pull and successfully remove all of the wire plus the end that clips on the plug. usually the wire would separate just above the clip leaving the metal still inside. it is hard to fish out. i still have some old wires laying around...perhaps i will see what i can do in the meantime and report back.

dwight.j.carter
02-21-08, 06:16 PM
Or you could be one of the lucky people with a 2000 or newer northstar that requires no plug wires. :thumbsup:

Edahall
02-21-08, 06:25 PM
perhaps you are more gifted than i am...this being possible, try it on junk wires like you planned on. i could not get a clean pull and successfully remove all of the wire plus the end that clips on the plug. usually the wire would separate just above the clip leaving the metal still inside. it is hard to fish out. i still have some old wires laying around...perhaps i will see what i can do in the meantime and report back.

On the wires for my 88 Eldorado, I drilled the old wires out. I saved the clips to use on the new wires. I then used a larger size drill and forced it into the boot to stretch it so I could get the new oversize wire in. I also used silicone spray on the wires to make it easier.

Submariner409
02-21-08, 10:54 PM
Glad you don't work on aircraft engines.

dkozloski
02-22-08, 12:38 AM
Contrary to popular opinion, I don't believe OEM ignition wires are shielded. To reduce EMI they are either resistance carbon core or helically wound solid wire. These measures reduce the radio emissions of the ignition system by increasing the rise time of the spark pulse.

Edahall
02-22-08, 12:43 AM
Glad you don't work on aircraft engines.

I actually do. LOL!! Their plugs and wires are a completely different design. The wires screw onto the plugs.

Submariner409
02-22-08, 10:21 AM
OK, semantics. No, OEM plug wires and 99% of aftermarket wires are not "Shielded" as in being braid-clad with a ground drain. They are constructed, as you said, using a couple of electromagnetic tricks to radiate much less EMI than straight wire. But Packard 440 is straight wire.

Aircraft plug wires are in fact shielded with braid or conductive covering, and that shield is what screws (so it won't fall off at 6,500 feet) to the specially constructed metal barrel aviation spark plugs.

I think my J-3 Cub (N42592) had unshielded wires with special clips on the plug ends. The Continental C65 was magneto fired, hand started, and the plane had no electrical system. To fly around NY in the 60's I had to hook a little NARCO VHF to a 12V REBAT sitting in the floor.

dkozloski
02-22-08, 11:25 AM
OK, semantics. No, OEM plug wires and 99% of aftermarket wires are not "Shielded" as in being braid-clad with a ground drain. They are constructed, as you said, using a couple of electromagnetic tricks to radiate much less EMI than straight wire. But Packard 440 is straight wire.

Aircraft plug wires are in fact shielded with braid or conductive covering, and that shield is what screws (so it won't fall off at 6,500 feet) to the specially constructed metal barrel aviation spark plugs.

I think my J-3 Cub (N42592) had unshielded wires with special clips on the plug ends. The Continental C65 was magneto fired, hand started, and the plane had no electrical system. To fly around NY in the 60's I had to hook a little NARCO VHF to a 12V REBAT sitting in the floor.
The majority of aircraft ignition wire is 7mm and screws onto both the mag and the spark plug. Your J-3 had what is called Connecticut fasteners for its unshielded ignition. J-3s had A65 Continentals. C series engines had a bigger bore and the smallest generally seen was a C-85.
I managed an aircraft engine overhaul shop for over ten years and personally overhauled hundreds of engines.