NGK plugs

[30-9]

Hi gents

Anyone know what the difference is between B4-L & B6-L for NGK?

[Phil Gillespie]

Originally Posted by 30-9

Hi gents

Anyone know what the difference is between B4-L & B6-L for NGK?

The heat range. B4-L will be a hotter plug than the B6-L.
Phil NZ

[Bored&Stroked]

Phil has it right . . . I can't see you running the B4-L . . . I run the B6-L plugs is just about every engine that isn't supercharged (and where this is the correct plug length for the heads I'm running).

Some guys buy late heads (like Edelbrocks), then they buy the old short reach plugs (like the B6-L) - which are completely WRONG for the later Edelbrock heads that utilize 3/4" reach plugs. Just pulled a set of Autolite 216's out of a set of late Edelbrock heads this weekend - and put in the correct plugs.

[30-9]

Thanks Gents

I’m running stock heads. I think the guy in the store mistakenly gave me B4. I didn’t realize it until after install and running them over a week. What side affect will this have? Should I eat the $30 and replace?

[flathead48]

B6-L the same as 3212 with 7/16 reach, I have been using autolite 216 but I thought I would try the ngk in my stock 48. Thanks, Rick

[JSeery]

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Information on NKG site: https://www.ngk.com/learning-center/...or---do-i-need

It depends on several factors, but too lean a condition or too hot a plug can result in engine damage.

[Phil Gillespie]

Can testify to running too hot a plug. They were B4-L along with a couple of other factors destroyed a piston, detenation.
I would opt for correct plugs B6-L. Cheap fix again for peace of mind as opposed to engine rebuild.!!
Phil NZ

[30-9]

Thanks. Totally agree, I pulled them out. Glad I asked

[flathead48]

I checked the plugs and they look a little foul.(black) I don’t know if it is because I run it once a week at fast idle until it reaches normal temperature and than shut it down or if the 216 are too cold.

[Bored&Stroked]

You can't check plugs by just running the engine, idling it, driving around town, shutting it down and looking at them - they will always be black/sooty.

You have to run the car on the highway, under medium to heavy acceleration, cut the engine and push the clutch in. Then - coast to the side and check them. Anything else is a waste of time.

[V8 Bob]

I switched from B6Ls to B4Ls many years ago to minimize plug fouling, but I run straight tripple 97s along with a pretty radical cam.

[Ziggster]

I'll be using the NGK B-6L as well for my mostly stock motor. Only reason though to use it vs the Autolite 216 was the fact that it has the removable terminal nut for use with hook style plug wires which is what I'll be using.

[Biggles]

NGK part number key:

https://i.postimg.cc/PxyzPyk3/NGK-part-number-key.jpg

[flathead48]

Thanks to all for the info, I apologize if I hi jacked this thread, was not my intend. I was just trying to be sure I was trying the right plug. Thanks again, Rick

[flatford8]

I’ve had a few of the 216’s come apart......in the spring I’m switching to something different....Mark

[Automotive Stud]

I prefer the hotter B4L plugs, but all of my flatheads have aftermarket cams and multiple carbs, so it helps keep them cleaner.

Since you already put them in the car I'd check them for signs of being too hot, like a white chalky plug, if it's fine I'd just run them.