spark plug recommendation
 

Guys,
I'm running Autolite 216's in my 286. Under sustained highway driving
I think the 216's are breaking down, the motor begins to run rough. The rough

running gives the effect similar to a wheel out of balance. All plugs are a reddish brown...the motor runs an L100 cam, lots of comp and a Stromberg
48 with # 50 jets. I've always preferred Autolites but I'm open to suggestions. The Autolite tech guy was no help.
Charlie ny

Re: spark plug recommendation
 

I use NGK B6L gapped at .025.

Re: spark plug recommendation
 

X2 on the NGK

Re: spark plug recommendation
 

Another NGK fan here! B6-L for short reach and B5-ES for longer reach like Baron or Flatattack.

Re: spark plug recommendation
 

After trying the H-10 and the 216 with not the best of luck I converted to the NGK and all is now good. The NGK B6L is the equivalent heat range to the H-10 and 216. The B-4-L can also be used if a slightly hotter plug is needed. With NGK the lower the number the hotter the plug for a gap with 12 volts go to .035
Ronnieroadster

Re: spark plug recommendation
 

X3 on the NGK's

Re: spark plug recommendation
 

I run the NGK B4L in my 286 CI Flathead. Seems to have eliminated my carbon buildup.

Re: spark plug recommendation
 

Please help a Dummy here. I have a 1941 stock Flathead in a Coupe. What number NGK should I buy?

Re: spark plug recommendation
 

B6L unless it is a tired oil burner,then B4L.

Re: spark plug recommendation
 

What does the reddish brown color on the insulator tell me ?....I'm thinking lean. ?
Charlie ny

Re: spark plug recommendation
 

Usually in a lean condition the insulator will be white. Lean conditions cause lots more heat the high heat burns the material off the insulator showing its original color. The best color is a light brown the reddish coloring is odd possibly caused by the brand of gas your using.
Ronnieroadster

Re: spark plug recommendation
 

Thanks Ronnie......
NGK's on the way, very eager to file a report.
Charlie ny

Re: spark plug recommendation
 

Back in my snowmobiling days, reading plugs was very important. We wanted to go as fast as possible, and that meant "leanin' 'em down" as far as it was safe to go. Of course, if you went too far, you ended up with a hole in a piston, which wasn't good. In those days, we said that if you bought a Hershey Bar and broke a piece off, the color of the broken part was what you wanted your plugs to look like.

These days, gas isn't what it used to be, and Hershey Bars probably aren't either.

Re: spark plug recommendation
 

It's close to Hershey chocolate.
Charlie

Re: spark plug recommendation
 

In as much as snowmobiles are 2 cycle and are oil burners, would you apply the same standards to a 4 cycle flathead that did not burn oil?

Re: spark plug recommendation
 

Charley: Back in the day with a 239 with my foot in it, I ran H-9 plugs with good success. The stock jet for the Stromberg 48 is .048 and I am thinking your use of .050 is too rich, hence the color of your plugs. JMO.

Re: spark plug recommendation
 

Hi Bill,
The motor is a 286 cu in 8BA......L-100 cam.....max comp EAB heads. The rule
of thumb is no more than 2 #'s over stock so there's where I stopped. I will definately
check the color of the NGK's after another run on the freeway.
Charlie ny

Re: spark plug recommendation
 

NGK plus they are indexed, meaning the hexes are all
oreneted in the same position. G.M.

Re: spark plug recommendation
 

I would. That color matched the pictures of the desired color in an old Motor manual I had. It's much easier to describe a Hershey bar to most people than to carry motor manual around with me every place I went.

Re: spark plug recommendation
 

Coco brown is a good color on spark plugs but they can be a lighter shade toward gray and still be good. White or yellow would be too lean and of course black is too rich or too much oil loss into the cylinder.

The best way to check them is to motor down the road for a good bit and then shut down the engine and coast to a stop. This will give a good running color. If the engine is idling too long then the color can change on you.