11 replies to this topic

[Midas Mk1]

Hey All,

On the drive to work this morning, my 1380 was a little spluttery and backfired through the carb pulling out of the 50 average zone,  having spent about 20 mins at those revs. Cleared once rev’d abit on the b roads

 

Got me thinking, and doing a search on here I’ve confused myself regarding ht lead / plug combinations. 

Had it dyno’d on resistor 6’s, but was strongly advised for 7’s due to the high end spec of the engine, (worked 1380).

 

 

As I run an aldon yellow with ignitor, lucas sports coil etc, I’ve always thought I needed resistor plugs, so have been using the BPR7’s, as recommend when I had the carb and timing set on the rollers last year.

I had the ignitor fail last year, needing replacement. 

One of my magnecor super dooper leads snapped last week, so I’ve replaced them with these

http://minispares.co...|Back to search

Now doing a search, Im confused as some say its fine running these type ht leads, others say otherwise.

It’s always been abit rough and spluttery when cold, but runs ok when warm! Do I need to go the resistor-less plugs (BP7’s)? Is there currently too much resistance perhaps?

 

 

 

Thanks

 

 

 

Edited by Midas Mk1, 28 April 2017 - 11:03 AM.

[Midas Mk1]

Anyone?

[Northernpower]

The 7's are a harder hotter plug and they're great if you're driving it hard for a lot of the time because it helps keep them clean. The 6's are slightly softer and they're better for slower revs but could break down at sustained high revs. The resistance shouldn't affect it.

[Midas Mk1]

Yeah, once pushing on I agree the 7's are the ones, especially with it being a high comp spec engine. Have 20 miles of fast twisties when it's used for work, so deffo see's the revs aha
Just thinking now ive got resistor plugs and leads, that do I need both, or is it one or the other. - ie don't want to create a weaker spark from having both resistor types like I currently have.

[Dusky]

What's a high spec? I couldn't run 7's in a 1330-643 cam-35x29 ported head on the road. Traffic made them foul up.

[Ethel]

Agree with Northern, it's more likely to be cold plugs fouling. The resistance of any plugs and leads is negligible compared to that of the plug gap. It's just there to suppress RF interference to any fancy electronics​ you have onboard - and your neighbour's telly.

[Northernpower]

I'd revert back to the 6's and see if they break down on your usual journey.

[cal844]

Isn't the resistor plugs used with electronic ignition? I have electronic ignition in all my minis, I run BPR6ES with non resistive leads iirc

[tiger99]

You are indirectly required by law to have either resistor plugs or leads, or something similar. The law doesn't specifically go into detail about how it is done, but the EMC Directive requires sources of radio frequency interference, such as the ignition system, to conform to certain standards, and before the EMC Directive there was other legislation specific to car ignition systems. The penalties for violating the EMC Directive can be very severe, but possible not severe enough, considering the amount of harm that can be caused by interfering with safety-related communications, or even worse (and it has happened!) directly affecting safety-critical computer systems in nearby vehicles. It is not just about ignorant pigs who don't maintain their vehicles properly blotting out someone's TV reception, which most people experience at some time or other.

 

Oh, and Plod in conjunction with the Radiocommunications Agency sometimes do drive-by EMC monitoring, so there is a good chance of getting pulled.

 

So you MUST fit one or the other, and as the Mini only passed its Type Approval Tests with resistive leads, you are on far safer ground using them, to original specification.

 

There is one other way of compliance which is to use aircraft type screened leads, coil and distributor etc. Probably expensive and may not fit the Mini.

[Midas Mk1]

I've checked the 7's today and they do look cold for the run I've done, so going to try 6's.

 

Im never not gonna run no resistance for EMC (when did I say that?? )  , but now i've got to order 6's, do I get resistive or non restive to try? Im running electronic ignition, and the leads in the OP.

 

If 6's aren coping i'll revert  back to 7's, but worth a try I suppose. 

 

On full chat over the twisties the 7's seem great, but on a cold morning they seem to have been fouling up when cruising, can't have the best of both I suppose.

Edited by Midas Mk1, 01 May 2017 - 07:31 PM.

[Northernpower]

 
On full chat over the twisties the 7's seem great, but on a cold morning they seem to have been fouling up when cruising, can't have the best of both I suppose.

That's not necessarily the case, you don't say what sort of ignition you're running. We did some some work running a higher voltage ignition set up (60,000 volts and a 35 thou gap) and ran with a grade hotter plugs at low revs and they didn't foul.

[tiger99]

I never even suggested, or thought, that you were going to violate EMC Regs. It was only an explanation of why the resistor in some shape or form is an absolute must. Otherwise the resistor makes no sense to most people.

By the way my old City E ran 35 thou plug gaps as one of the tweaks to get more torque to cope with the 2.95 final drive. Seemingly standard points although the coil must have been a bit different, and it was ballasted. It never fouled plugs, but the supposedly correct Bosch plugs lasted a couple of hundred miles only, and burned, and it really had to have Champions or I think NGK.

If I was fitting electronic ignition to any engine I would try opening the plug gaps to 35 thou. There is some small gain to be had.