What plugs

[triumphelan]

Hi ,what plugs do the list recommend,and what gap ?
regards John

[ElliottN]

Discussion of this subject is liberally sprinkled throughout the forum. Seems to me the weight of opinion leans to NGK plugs - BP6ES (for regular road use), BP7ES (for extended high speed running) or BP8ES (for sustained high engine speeds - e.g. track).

I haven't seen the gap debated but my workshop manual (based on Champion N7Y, for which the BP7ES is the NGK equivalent) recommends .020 to .023 (inches of course). NGK themselves recommend .024 for these plugs. I'm a road user and am happily running BP6ES's and start them at .021.

[triumphelan]

Thanks Elliott,that`s just what I am using .
Regards John

[rgh0]

I changed the plugs on the Plus2 over the weekend and it reminded me of why I prefer NGK over Champion.

About 3 years ago when I last change the plugs I had put in Champions because I could not get the normal NGK BP6ES I normally use. When I came to pull them out on Saturday for the first time since they were installed I ended up breaking the insulators on 2 of the 4 plugs. The Champion insulators are much weaker and much easier to break if the socket gets a little out of alignment on the plug and puts pressure on the insulator. This is not a one off incident but something I have experienced regularly with Champions that have never happened with NGK's I had just forgotten it because I stopped using champions about 20 years ago.

The warning though is about what happened next. The plugs were the resistor type plug and these have a spring and resistor section inside the insulator. When the insulator broke the small resister section dropped out and fell down next to the base of the plug. I could not see it and when I pulled out the plug it was sitting on the lip of the plug hole. It could easily have dropped in and ended up putting dings in the piston and head as recently discussed in another thread. Lucklily I saw it and pulled it out before any damage was done. When the next plug broke exactly the same thing happened but I was ready for it and pulled the bits out of the spark plug well before removing the plug.

If you ever break a plug of any type always have a close look before removing the plug.

By the way the temp ranges recommended in the previous post are what I use also.

Rohan

[ppnelan]

I too have experienced several Champion plug insulators snapping off. NGK don't seem to do this.

Matthew

[ElliottN]

Well, to be honest Rohan - it was really your recommendations I was echoing!

Has anyone ever tried the NGK "V Groove" plugs? They sell in Oz for the same price as standard plugs now and NGK's claims are for spark at the perimeter of the elctrodes (better ignition) and more reliable spark (e.g. same result for less Kv's).

cheers,

[rgh0]

Elliot

Over the years I have tried a huge range of alternate plug designs from fancy multiple earth electrode types to fancy exotic metal fine wire centre electrodes including the V groove earth electrode types.

None made any significant performance difference and most cost much more than a standard plug and were harder to source. Some may have a longer life in modern engines due to reduced electrode erosion but in a Weber twin cam with its relatively poor mixture control and relatively high oil consumption plug erosion tends to be the least of your problems compared to plug fouling. No many people are trying to get 50000 plus miles on a set of plugs in a Twin Cam Lotus as are required by modern regulations for modern engines.

I ended up concluding a standard NGK changed regularly works best in terms of performance, reliability and money for me.

Rohan

[Dag-Henning]

I have ordered some NGK BP8 EVX mainly for racing use. They are supposed to be the top choise, but time will show........We still have -10 deg C. during night , so season is not quite here yet.......

Dag

[richardcox_lotus]

Sorry to bounce this thread back into the domain, but I'm thinking of changing my plugs, from an NGK BPR7ES to the BP6ES range & need a little advice.

Need to change for the usual reasons - current set seem easy to foul in traffic with subsequent misfires & general bad running, until removed & cleaned.

My question is I have resistance-type ignition leads (Again, NGK). Can I use these type of leads with a non-resistance plug ? What happens if I do ? (Will it hurt ?)

Cheers

Richard
72 Sprint.

[rgh0]

Richard

The resistance built into the leads and plugs is about damping out radio frequency waves generated when the spark plug fires. These cause interference to radios and other electronic devices. Important in modern cars with their multiple electronics but not critical in your Elan unless you like listening to the radio.

If you have resistance leads then no real need for resistor plugs also in most cases.


regards
Rohan

[richardcox_lotus]

Thanks for the reply Rohan. That's good, it means there's something less for me to worry about, as the radio is also u/s !! Hey ho. Plugs now on order. I'm hoping for a big improvement in running - Le Mans 10 days away !

Rgds

Richard

[steveww]

I have been told that the standard spec BPR7ES are a bit too cool for the twinc and that the BPR6ES are better and tend to self clean better.

I am currently using the BPR6ES in my twinc and they certainly appear to be keeping cleaner.

[Hamish Coutts]

Agree Steve.

Mine had BP7ESs when I got it but the engine didn't run too well and it oiled the plgs a bit.

Now happily running BP6ESs.

On Rohan's point about insulators snapping. For many years, I've experienced Champions giving way with little sideways force. I also had a set of Unipart plugs (don't remember the part no). They must have been made by Champion as they snapped just as easily!

I've also tried a set of Bosch plugs with a bit of success but I usually end up back with BP6ESs.

Hamish.

[thor]

SO, what's the difference between BPR6ES and BP6ES ??

[rgh0]

The "BPR6ES" are resistor plugs the "BP6ES" non resistor

regards
Rohan