Routing plug leads on twin plug engine?

[911hillclimber]

About to start making the leads for my 3.2 twin pluged engine with Clewett high voltage ignition system.

A lot of words everywhere about separation of leads to the engine (and hence ground) but also which lead to another. I'm told it is ok to route in parallel leads to the same cylinder, but not to have a lead to, say cylinder #1 and cylinder #3 along side each other. At the moment I can't see a way to avoid such lead runs and avoid the lot looking like Spaghetti Junction.

Leads to #1, #2 , and #3 would naturally run from he ignition coils to the top set of plugs of those cylinder along the top of the cam cover, hard to see how to avoid it.

so, is all this a load of ballony and I should run them neatly as possible and ensure they do not touch the engine/ground?

Here is the engine.
In this shot image a lead to #1 cylinder top plug from the left hand coil pack and another lead from the right hand coil pack running under to cylinder #1 lower plug.
However, also imagine a lead to #3 upper plug and the lower #3 plug, the leads will/could be running parallel to each other.

[Gary71]

I’d just go neat and well supported, unless the insulation has broken down it shouldn’t matter.

[Lightweight_911]

.

Don't know if these help - the twin-plug engine I used in my 904 - not with the Clewett ignition system but distributor-based.

I just routed the leads for the simplest/neatest solution - never had any misfiring problems.

[911hillclimber]

I think the issue for me is the voltage is around 40,000 at some instances and can be electrically 'noisy' and that interference can get back to the 'ECU', = miss-fires.
You can see the cross over/touching on Andy's engine on the left side.
This engine ran faultlessly for years with old-school ignition with leads touching and crossing everywhere.

However, everything is new, everything is mega expensive, so it MUST be ok!
A lot of mumbo jumbo surrounds all these fancy systems, so bull to sales talk...and back.

I think the neat/short spaced routing is best, but just want this thing to run on 6 (or is that all 12?) every time.

[Jonny Hart]

As per two previous postings, the voltage is dictated by the plug gap, not the ignition system. As long as you don’t go too big, the secondary voltage is unlikely to be much above 35kV so the insulation on the leads should be fine.

Generally speaking sparks tend to ‘escape’ on edges of metal, essentially acting a bit like an antenna. So that’s typically at the boots near each lead end. You are less prone to noise with an inductive system since power is around 5 times less than CDI - not as sharp a rise time.

[911hillclimber]

Good to read, thank you.
Gaps set Tom 0.9mm as per Clewett pages of instructions.
Plugs came much tighter, about 0.7mm setting.