This is for my buddies ride.. He was running bosh plat. plugs numbers off em are as follows WR9FP R3 289.. Having a lot of pinging with em when the engine gets hot, can anyone recommend a different heat range/plug? Thanks!

 

Get ac delco brand

 

I also use AC Delco! Never had any problems with them.

 

I've never figured out exactly why, but Bosch Platinum plugs perform completely awful in V8 motors. They seem to foul out very quickly. They work great in 4 cylinder engines though. I've always had good luck with AC Delco plugs in my V8, and even better results with Champions. All the fancier "gimmick" spark plugs really are nothing but gimmickry. Never tried the AC Delco "rapid fire" plugs, so I can't really comment on them from personal experience.

 

AC DELCO RAPID FIRE!!!!!!!! nothing less!!!!

 

can anyone recommend a heat range?

 

You never mentioned what your buddies ride was.

 

350 186 iron heads, 10.5 to 1 comp ratio forged internals, 650dp, rpm intake, some sort of comp grind... thats all I really know about the engine..

 

Doesn't sound like an extremely radical motor. In those cases, what I usually do is just start out with the recommended plug for that particular year and motor. If it doesn't run optimal with the stock range plug, maybe go one step colder, but try the stock heat range first.

 

yeah its nothing too radical, it only made like 350 hp at the crank and 380 flbs or so, just a mild street build. I believe the above mentioned plugs were the stock range, I'll tell him to try something a range lower and go from there. Thanks!

 

r45ts or i think like an r44ts is a colder plug