Used these on other combos, older LA 318s. What about the magnums?

Yes all my cars and power equipment use either Denso or NGK plugs just because they are reliable and last forever

Gus

Im with Gus.We used a lot at the shop.Run them in almost all we have also.Last set in my 440 went at least 5 years.Just replaced them as maintaince.They were still looking good.Rocky

Stay with the stock heat range, Adam71.

I tried a colder NGK in my 360 Mag and found the off-idle response was a little soft. Went back to new Champions with the proper number and it came back.

Can't explain it.

I would always put champions for sure.

No matter what I put it in, on stock engines, I try to put same heat range. I like the NGK in my older stuff, just never had a magnum engine before

I use NGK in every car I put plugs in in my repair shop, I have seen just about every plug brand with a bad "new" plug. Bosch are the worst we have to fix mis-fires caused by other people putting in new bosche plugs probably once a month on average. Autolite Delco and Champion are usually ok but ocasionally we see an issue with one of them.

I went to extent of checking resistances in a variety of manufacturers new unused plugs all same application. The only consistent plugs were ngk's all about 5000 ohms. Others were wildly variable in several cases. I put some ngk's in one of my darts and immediately saw improved starting and engine runs a wee bit cooler as well, (slightly colder plug installed too). I won't use anything else after that. Small engines run better with ngk's too in my experience.

Dave Ill agree Bosch are total crap.In 30 years at the shop I dont know how many setsI had to replace because they ran like s--t.Peopl pay big bucks for them and total trash.Only say 1 car that ran with them.Oh yeah my kid put a set in a 61 Dodge he had.Only thing he could get at the time.Didnt wabt to start idled bad poor power etc.I got some Autolites i had used put them in and it started super quick ran great and ideled fantastic.Now we run almost all NGKs.Rocky

the weekend must be here! (time flies when you're having fun)

x2, especially two-strokes.