Flathead Sparkplugs - What are you using?

I am running an Autolite 216 in my flathead and am having trouble once in a while with fouled plugs. Would it help to switch to a hotter plug? Was just curious what others are running whether it be Champion, NGK, Autolite, etc. Don't know which is best. Any info would be appreciated.

 

I had the same problem ..NGK's work great.

 

Champion H10c, no problem at all.

 

What number NGK's are you running? Does anyone know if they have an extended reach plug?

 

I run H10C in my fresh flathead and H12's in my somewhat tired one. It made a BIG difference; I was screwing new ones in there every few weeks but have had the 12's in it for a few years now.​

 

i also run autolite 216 in my flat head,havent had a problem yet,but
i would also like to know what # ngk plugs to run

 

I run NGK B6L plugs. They are extended reach.
If they foul a bit, take them up a heat range.

 

Autolite 295 on gas.
Autolite 303 on alcohol.

 

NGK B6L.................best I've used out of all of them for flatheads.....

CB

 

champion H10

 

I tried these, until the valves flattened them. They do have a longer reach. If you currently use Champion H10 or H10C, double check clearance if replacing with the NGKs.

 

Those valves like to come up and smack those long plugs especially with high lift cams. Clay them upon assembly for use of different plugs and then you will know. I stick with the h10s myself. They've been running in flatheads forever and why reinvent the wheel.

 

you couldnt make me run a NGK in anything but a honda. H10C is what i would run and if you have to have one late at nite because of some disaster to the plug, you can always hit the walmart and get them in the lawnmower section.

 

motorcraft a7c is comparable to h10's but are slightly shorter for extra clearance over valve

 

Thanks to all for the info. I'm off to the parts store in the morning.

 

What he said. Never had a fouling problem,but had to do away with metal wire looms I used to run with the hot inginion , it would glow at night.

 

I hear champion plugs are junk anymore. I have a set of autolites on the shelf but I haven't used them. I'm running NGK in mine for a few years now with no problems.

 

WHAT # NGK DO YOU USE??

 

The problem with ANY long reach plug;
is it being used in a after market head with a high lift cam??
(plug depth varies all over the map with after market heads!)
If the valve to plug electrode clearance is TOO close, ANY plug is going to get "mashed."

The clearance needs to be checked before using them. (by "claying" them)
If they are too close, extra thick gaskets ** on the plugs can cure the problem.

** The extra thick gaskets also allow the plugs to be "indexed." (electrode facing the intake valve)

 

Same as the rest, B6L

 

That's what I used to think. Then I decided to use what works best.