Im installing an MSD HEI distribuitor, hopefully with a blaster coil, and I was wondering what spark plug to use. I put the Bosch 4+ Platnums in about 3000 miles ago, but will prob change them out when i put the new ignition in.
I was reading in another post and someone said that MSD reccomends NOT using the bosch 4+ with their ignigions (something about the resistance). I dont know if this is true, I just need to know what plug to use.

I dont want to run crappy plugs, money isnt a problem... not that im rich but im young and i spend all my money on my car so i dont care, as you can see i spend about 8dollars a plug for the bosch 4+.

 

Stock replacement AC Delco’s or comparable NGK’s. Conventional plugs, no plantinum or other BS.

The only thing that’s good about plantinum plugs is that they do not wear out anywhere near as quickly as conventional plugs. Otherwise they suck.

On my crossfire car I was able to run stock AC plugs + stock ignition with gaps in the .055-.065” range and saw a big improvement in gas mileage. If you want to play with this start with a gap a little wider then stock and widen it about .005” at a time till you start noticing any problems (usually missing up top), and then back off a few thousandths.

 

AC Delco Rapidfire.

 

bosch is terrible. and ironically, so is busch. gross.

 

If you can find a copper core plug, run with it. I do like Bosch plugs, depending on the application.

If you run a capacitive discharge system, like the MSD, you do not want any of the Bosch platinum stuff as they have a platinum core.

In any thirdgen app, you do not want the Bosch +4 plugs b/c of the obstructions to the flame front that the prongs present.

The resistance is a killer for the system. Likewise, while most platinum plugs have it on the tips only etc., I will avoid those as well. You want to find the plug with the least resistance you can get. Likewise the wires, but that is a whole other discussion as certain companies can play with the resistance readings.

I have not had a problem with the Bosch copper cores or the regular AC Delcos in these apps. Don't know about other types like the rapid fires etc. as I don't bother using them.