Spark Plugs

[RamD50]

So as work continues on my truck my father brought to my attention that the spark plugs I am using are too cold for my setup. I'm running a twin Mikuni 2.6L and it backfires like crazy and my current plugs foul up quickly. I know that the carbs are running a little on the richer side, but he told me he used to run some hot plugs that had a green ceramic and had a tip similar to a splitfire plug. I am currently running some standard Champion RN12YC plugs with an accel super coil. Any suggestions (besides leaning out the carbs, that's on the list)?

[geezer101]

The twin Mikunis were part of a performance package. They require their own cam and I've got a feeling the distributor was sprung differently as well. Even the secondary vac actuators on the carbs were sprung differently too. I would start by using NGK's or Denso plugs with a higher heat range (maybe disconnecting the vac advance and capping it off...?) I think you're going to need your distributor modified so the engine will have a better tune.

[RamD50]

The twin Mikunis were part of a performance package. They require their own cam and I've got a feeling the distributor was sprung differently as well. Even the secondary vac actuators on the carbs were sprung differently too. I would start by using NGK's or Denso plugs with a higher heat range (maybe disconnecting the vac advance and capping it off...?) I think you're going to need your distributor modified so the engine will have a better tune.
I'll look into the distributor, any specific NGK's or Denso's you recommend?

[geezer101]

I couldn't recommend a particular plug for the twin carbs, sorry. I thin you'll need to go up 1 with the heat range and either buy a pregapped plug 0.9mm or regap them yourself with feeler gauges as I've done. I've always used NGK's when replacing plugs and found them pretty solid.

[pennyman1]

with NGKs for each number up is a 1/2 step range colder - odd but true.

[geezer101]

Sorry about the confusion I might've caused - pennyman is correct. If you want to know how to decipher codes on NGK spark plugs check it out here http://www.ngk.com.au/spark-plugs/product-information/part-numbering-system

[pennyman1]

Post that to the manuals section, Geezer