Paul L

I am thinking of changing the spark plug wire configuration on my 1974 in the spring from underneath (stock) to over-the-top with looms, brackets, etc. I still have the pre-HEI ignition system with points and condensor. The wire sets (I'm looking at Accel) available seem mostly to be 8-mm rather than the original 7-mm. Can the old non-HEI coil work with 8-mm wires?

vette427-sbc

I have a points distributor in my car now with Accel 8mm wires. No problems here

Golden

Wire thickness makes no difference to their operation

Paul L

Thanks for the replies!

noonie

I prefer the over the top too.
The biggest problem is with the oem ramhorn manifolds, not really condusive to that. Other designs of GM cast iron manifolds worked well that way.

I'm looking for a good solution as well, but haven't searched or found a good one yet, short of changing to headers, which have worked well in the past.

Mike Ward

Paul,

I found the 8mm wires to look out of place and be difficult to route correctly. My locals flaps found me a set of black silicone 7mm wires with black boots made by Blue Streak. Not expensive, look right and work very well.

Paul L

Thanks Mike. A local flaps is a sponsor of our Club and can get me "just about anything" through his extensive industry sources. I won't see my car until April so there is lots of time to gather parts together.

But if I don't like the over-the-top look I have a new set of the "real thing" stowed away in the basement.

midyearvette

i believe the core wire is all the same diameter either in 7 or 8 mm wires....at least the brands i have seen...the only difference is the outer jacket is bigger in the 8 mm..jmo.....

MotorHead

That is correct, the wire is approximately the same diameter inside, constructed differently in some cases like solid or wound etc. The exterior diameter is mainly for protection against heat, I have seen 10mm wires on race cars but it's just more insulation around the the same diameter wire inside. Sometimes 10mm wire will have a slightly bigger core wire though

Paul L

I've ordered the 8-mm Accel 4040K in black.

MotorHead

What no yellow wires ?

Paul L

No, not yellow or red or blue . What tool do you use to cut the ends to expose the core before crimping? Just an Xacto knife? I will have the Accel 170042 crimping tool to finish off.

Gordonm

I use a pair of wire cutters that have different size holes for the different size wire. This way it just cuts the insulation. Exacto knife you can get into the wire. The insualtion comes off pretty easily.

MotorHead

I use MSD wires and the insulation cutter is part of the crimping tool included in all the cut yourself wire kits. The Accel crimper might have it too. You can use an exacto knife just be careful not to nick the wire as it could eventually break off

FB007

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Golden

Uh no, the load placed on an ignition system is determined by how hard it is for the spark to jump any air gaps in the system.

The same engine, with the same coil, will pull exactly the same voltage through the system whether it's HEI or points.

FB007

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Golden

What a load of rude garbage.



You state that points use 7mm and HEI 8mm. There's no difference in the way the systems are loaded so the insulation is in no way connected to the system type.



Whether a race car uses HEI, MSD, DIS, or Magnetos is irrelevant to the required ignition shielding.

A Bosch OEM coil is capable of producing just as much peak voltage as any of these systems.

HEI is used because of it's reduced service requirements and it's transistor control improves coil soak time. As are DIS or what we call coil packs.

Magnetos and MSD (capacitor discharge) systems are used because of their prolonged spark duration, not because of a higher peak voltage.

Voltage always takes the path of least resistance, only once the air gap at the plug has an exceptionally high resistance does it look to 'escape the insulation'.

You made sweeping inaccurate generalisations in an attempt to belittle Motorheads post and sound superior.

His argument that thicker insulation gives improved thermal protection is no less valid than your vague assertion that anything other than points needs a thicker lead.

problemenko

My wire is bigger than yours.

FB007

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