Dual plugging: 14, 12 or 10mm?

[mattcfish]

I have used 10mm in the bottom of a big valve head (lots of material left afterwards) and have found suitable NGK spark plugs. Used to use BPR7ES on the top and D6HA in bottom IIRC.

Thanks but, D6HA is a 12mm plug. The 10mm would be NGK C6HSA.

[Garnet]

Thanks but, D6HA is a 12mm plug. The 10mm would be NGK C6HSA.

It doesn't look like there is a C6HSA avialible any longer. There still is a CR6HSA, but if you want non-resistor will need to go down one heat range to a C7HSA.

[mattcfish]

Thanks but, D6HA is a 12mm plug. The 10mm would be NGK C6HSA.

It doesn't look like there is a C6HSA avialible any longer. There still is a CR6HSA, but if you want non-resistor will need to go down one heat range to a C7HSA.

Sparkplugs.com still has them listed. http://www.sparkplugs.com/more_info.asp?AAIA=&pid=2507

[Major Softie]

That's another thing to consider: making sure you set it up to use a plug that is not likely to be discontinued. Something that is used in a small-block Ford or Chevy, or one of the main Toyota, Nissan, or Honda engines, is going to keep being made for a long time.

[StephenB]

I have used 10mm in the bottom of a big valve head (lots of material left afterwards) and have found suitable NGK spark plugs. Used to use BPR7ES on the top and D6HA in bottom IIRC.

Thanks but, D6HA is a 12mm plug. The 10mm would be NGK C6HSA.

You're right ... I got my facts wrong: I have a 12mm plug in the botton and they are available as D5, D6 and D8 (mostly Honda lawnmower application!)

[StephenB]

I have used 10mm in the bottom of a big valve head (lots of material left afterwards) and have found suitable NGK spark plugs. Used to use BPR7ES on the top and D6HA in bottom IIRC.

Thanks but, D6HA is a 12mm plug. The 10mm would be NGK C6HSA.

You're right ... I got my facts wrong: I have a 12mm plug in the botton and they are available as D5, D6 and D8 (mostly Honda lawnmower application!)

[mattcfish]

That's another thing to consider: making sure you set it up to use a plug that is not likely to be discontinued. Something that is used in a small-block Ford or Chevy, or one of the main Toyota, Nissan, or Honda engines, is going to keep being made for a long time.

Lots of Honda generators and ATV's (and 1950's Aston Martins ) use the NGK C6HSA http://www.sparkplugs.com/results_fitment.asp?pid=c6hsa
Maybe that's enough to keep them around.

[Garnet]

Non resistor plugs have been disapearing over the last 5 years. C6HSA is not in my Canadian 2008 NGK catalouge, but the resistor is.

That does not mean that NGK does not still make them, but that they do not ship them to all markets. For how long, who knows. Spark plug sales in North America are on the decline, as they are almost a liftime fitment on new vehicles. 10 years ago I sold around a thousand plugs a month, now we might sell three thousand in a year. As a result all plug manufactures are trying to streamline operations and cut down on low volume numbers.

Most small motors work fine with R plugs in place of non Rs so that is a place that cut backs are possible. I can only think of a couple of Bosch non resistor plugs left and there are none left in Autolite or Champion, (in Canada).

[mattcfish]

Are we slipping into the dreaded resister vs non-resister plug discussion?

[Garnet]

Are we slipping into the dreaded resister vs non-resister plug discussion?

God no! I think that is overblown, just ramblin on.