Spark Plugs again

[bob46320]

What are the current thoughts on 18mm plugs for the 1932 RN (Low compression head).  With changes in fuel composition are NGK A6, Champion B16 plugs still the best ?  After a long run, the electrodes are clean and creamy white, but the foot of the threaded section is lightly sooty.  I have found that running on the 98 (premium petrol) reduces vaporisation and the engine runs better.

[Dave Mann]

I treat spark plugs as fit and forget, our RNs run champion D16.

[bob46320]

Thanks for that Dave. 
So do we think that changes in fuel from Leaded to Un leaded to Bio fuel and who knows what wouldn't need any changes to fuel ignition ??
Bob

[Ruairidh Dunford]

I changed to D21s a number of years ago, the cars seem to run much better on them.

[Ivor Hawkins]

My pal has an MG 18/80 and fitted new NGK spark plugs as part of an engine overhaul and it refused to run on all six. After messing around with points, condensers and all the usual faff, he raked through a box of old Champion plugs, all of which were at least 70 years old, after fitting the car runs perfectly on new petrol.

Exactly the same happened with a pal’s Norton dominator...old Champions transformed the bike, it just didn’t run right in new NGKs...we are now trying to find the NGK boxes to see if they are counterfeit plugs.

[Ray White]

My pal has an MG 18/80 and fitted new NGK spark plugs as part of an engine overhaul and it refused to run on all six. After messing around with points, condensers and all the usual faff, he raked through a box of old Champion plugs, all of which were at least 70 years old, after fitting the car runs perfectly on new petrol.

Exactly the same happened with a pal’s Norton dominator...old Champions transformed the bike, it just didn’t run right in new NGKs...we are now trying to find the NGK boxes to see if they are counterfeit plugs.

Either counterfeit ... or made in China.  (You take your chances if buying off eBay).

[flywheel1935]

Changed from NGK to Champion, and Ruby runs loads better, BUT did a few other jobs as well, such as timing and e-ignition, so could be plugs !!!!

[Tony Press]

If you ask Mrs Google about:

'fake vs real ngk spark plugs'

Threr are a number of stories 

[Parazine]

This is a good guide:

https://www.slideshare.net/athangal/dist...spark-plug

[andrew34ruby]

I changed to D21s a number of years ago, the cars seem to run much better on them.

My Ruby is fitted with Champion D16 plugs. What differences might I notice if changed to D21s?