VVC plug leads

[CycleSi]

How critical is it to use the correct (longer) length VVC plug leads?

My K-series (with VVC head) started to have the occasional misfire/hesitation so my engine builder gave me some new non VVC leads which are slightly shorter than VVC leads BUT the engine runs smoothly with no misfires/hesitation and everything seems perfectly ok.

Should I bother replacing them with 'proper' longer VVC leads if all is well? There doesn't seem much point unless somebody can correct me.

[Steve Sheldon]

I recently replaced mine with a set of original leads but, if they are working, length is of no importance as far as I am aware. You might have an aesthetics issue for some fussy owners. Spark impedance and radio interference can come with cheaper makes but your engine builder no doubt uses the same supply for all his engines.

[revilla]

It's not the actual flexible lead that is longer on the VVC, it's the solid body (or whatever it is called) that goes down to the terminal of the spark plug. The cam ladder on the VVC head is deeper, therefore the plugs are deeper set into the head, I believe by 12mm. I would be concerned that your leads will not be making a reliable connection to the plug terminal and while it may be working fine now, may not be reliable at some point in the future in the presence of moisture etc.

[Mankee]

Hello Si. Do you still use the early RXXX K-series ignition setup with a distributor on the end of the inlet cam? When I ran my old 200bhp engine using a distributor and VVC head, I cut-and-shut some new Lucas £20 VVC ignition leads by chopping them down to a suitable length and grafting the distributor ends on, retaining the longer VVC plug ends. They worked perfectly for years, lost zero power and no need for snazzy leads!

However, if your current leads work fine, I'd be tempted to leave them alone. I think DVA has suggested that non-VVC Magnecor leads (and possibly some other brands) can have their spark plug connectors pulled through the boot more to work with VVC heads. Maybe your leads have had this treatment?

[CycleSi]

 

That's exactly the kind of thing I wanted to know.

I'm based near High Wycombe in South Bucks; who should I go to get the proper VVC plug leads? Any recommended brands - I'm more concerned by performance & quality rather than price.

[CycleSi]

 

It's an EU3 engine; wasted spark ignition (no distributor).

[Mankee]

I've just converted to EU3-style wasted spark now. So do you have two coil packs in the cam cover and two leads? First, check that the coil packs are right for a VVC head; they can be identified by a red boot, as opposed to black boot for non-VVC. And then for the two-lead set, something like this:

http://www.ebay.co.uk/itm/180989336573

There should be plenty of online retailers or even DVA might supply them himself.

[Cookie Monster]

Si

Sorry for the thread hijack - what are the make of the non VVC ones pls?

You may recall I have had numerous misfire issues with leads.

 

Can't help with VVC ones I'm afraid but my experience of Magnecor leads was they were awful but I know plenty us them happily. I can only assume I had a duff batch.

[CycleSi]

I'm not sure what make they are and I can't check as the engine is away being rebuilt at the moment, but I'll let you know at some point. I was always led to believe Magnecor leads were the business, but it seems like they have had some quality issues lately.

How are you progressing with diagnosing the other issues with your car?

[Mankee]

An alternative to Magnecor is Formula Power in London, who, amongst other things, make fat old 10mm leads:

http://www.formulapower.com/index.php?main_page=product_info&cPath=1_116_2958_2962&products_id=3878

[Cookie Monster]

Hi Si

Zero progress so far - I've had no time with the new job!

Hopefully in the next few weeks.....