Ideal spark plugs for M10 with twin Webers?

[antares242]

Hello folks, I know this is a wide subject, so I decided to create a different thread on it. What would you say are the best sparkplugs for those who have a twin Weber setup? In my case I have Weber DCOE 45s, 292 cam, ported head and MSD 6al and coil. I started with the factory recommended Bosch W8DC and although they work fine for a while they go completely black after a while (even though I have adjusted the mixture). Then I used Bosch FR8DPX (platinum) but eventually the same thing happens. I've also tried NGK BPR5EIX (iridium) same thing.. now this guy recommended Autolite AP64 but this time I'd like your advice first!! Thank you!

[Simeon]

Go with the simple copper NGK plugs but probably go with a hotter plug (higher heat range). If your plugs are constantly fouling then a hotter plug should burn the deposits off. Different engines like different heat range plugs depending upon their condition and cylinder temperatures. The ideal plug is hot enough to burn deposits but not so hot it causes detonation. 

 

Pictures of these black plugs will allow the plug reading gurus to confirm. 

[Chris_B]

First of all, I believe that the consensus is that 02s run best on the Bosch or NGK copper plugs. The Bosch W8 is already a pretty hot plug. Perhaps you should be looking to your carb tuning for a solution. Do you had a wideband 02 sensor/AFM?

[antares242]

Go with the simple copper NGK plugs but probably go with a hotter plug (higher heat range). If your plugs are constantly fouling then a hotter plug should burn the deposits off. Different engines like different heat range plugs depending upon their condition and cylinder temperatures. The ideal plug is hot enough to burn deposits but not so hot it causes detonation. 
 
Pictures of these black plugs will allow the plug reading gurus to confirm. 

Thanks Simeon, I suck at "translating" spark plug codes to heat levels. What would you say would be a "hotter" plug than the standard W8DC?

['76mintgrün'02]

https://www.ngk.com/learning-center/article/200/how-do-i-find-a-colder-or-hotter-plug 

[Chris_B]

Bosch plugs go up in heat range, so a 9 plug would be hotter than an 8 plug. What your are doing is treating symptoms rather than the cause.

[antares242]

First of all, I believe that the consensus is that 02s run best on the Bosch or NGK copper plugs. The Bosch W8 is already a pretty hot plug. Perhaps you should be looking to your carb tuning for a solution. Do you had a wideband 02 sensor/AFM?

No wideband or any of that. In regards of carb tuning, after lots of trial and error I found out that 65 F8 idle jets are the ones that allow me a wider range of mixture adjustment as I was previously using 55 F8s but those always tended to go on the lean side even if I had the mixture screws almost all the way out.. so long story short, I think I've found my ideal balance (not too lean not too rich) now but still my spark plugs go really black.. I'll attach some pictures soon! Thanks

[KFunk]

I’ve just been running good ole NGK BP6ES forever, I think. Around 11 years on DCOEs. The 5 is a little hotter and the 7 is a little colder if that’s what you want.  I’ve run the bp6es with stock cam and points, and now 292 with cranecam xr3000 with ps91 coil.  Can’t say if they’re perfect, but never given me any problems.

[antares242]

Bosch plugs go up in heat range, so a 9 plug would be hotter than an 8 plug. What your are doing is treating symptoms rather than the cause.

What would you suggest the cause could be? As I said in a previous comment, I'm confident I'm running the right mixture balance after trying different idle jets and adjustment.

[Simeon]

It depends what they are fouling with. If you post your pictures we can give you a clue. 

[antares242]

It depends what they are fouling with. If you post your pictures we can give you a clue. 

Will do tomorrow, thank you guys

[antares242]

https://www.ngk.com/learning-center/article/200/how-do-i-find-a-colder-or-hotter-plug 

Thanks! This will go to my favorites [emoji108]

[NickVyse]

12 minutes ago, KFunk said:

I’ve just been running good ole NGK BP6ES forever, I think. Around 11 years on DCOEs. The 5 is a little hotter and the 7 is a little colder if that’s what you want.  I’ve run the bp6es with stock cam and points, and now 292 with cranecam xr3000 with ps91 coil.  Can’t say if they’re perfect, but never given me any problems.

 

what he said

[antares242]

I’ve just been running good ole NGK BP6ES forever, I think. Around 11 years on DCOEs. The 5 is a little hotter and the 7 is a little colder if that’s what you want.  I’ve run the bp6es with stock cam and points, and now 292 with cranecam xr3000 with ps91 coil.  Can’t say if they’re perfect, but never given me any problems.

Thanks KFunk, would you say BP5ES would be drastically different if I want hotter?

[antares242]

Thanks. So if the equivalent of the factory W8DC are BP5ES that means you're actually going colder with BP6ES? Taking in consideration my problem, wouldn't it be better to go hotter than factory?