Spark plug thread

Newoldstock

Newoldstock

New Member
#1
#1
With the shrinking stocks of BP7ES and assorted heat range NGK spark plugs causing grief what are you switching too?

If there is an "R" in the code spare me the details, they don't call me old school for nothin ya know.....
These are Magneto engines and I am not willing to change to a R type without good reason.

I am looking at the Champion N7YC.
 
Newoldstock

Newoldstock

New Member
#3
#3
Combination of boot resistor, resistor spark plug and high flux density flywheel magnets seems to be causing some premature coil failure.

I am going to stick to my guns on that until proven one way or the other.

RF noise has not been an issue to this point, I can barely hear the radio at all.....
 
OND

OND

#4
#4
I know you don't like the AR3910X plug....but I'm sticking with it. We've had really good luck with it in racing karts and mini bikes.
 
N-gin

N-gin

New Member
#7
#7
Newoldstock said:
Combination of boot resistor, resistor spark plug and high flux density flywheel magnets seems to be causing some premature coil failure.

I am going to stick to my guns on that until proven one way or the other.

RF noise has not been an issue to this point, I can barely hear the radio at all.....
Click to expand...
I can totally agree. The resistor spark plug itself is for suppressing noise, however it also lengthens the dwell time, which is good for high RPM.
If you use a resistor boot and plug that is too much and will reek havic on your coil.
Done properly you can run a resister plug with a solid wire, and nonresistor boot. However you will be limited to the resistor in the plug, which is not very optimal at all, but will work better.
As I understand it: the best setup is to run a specific resistance boot to whatever RPM you want to run your engine, with a nonresistor plug. For this too be optimal you will need to go to a solid core wire, as resistor type wires will add resistance as well.
To much resistance will rob amps. To find the perfect balance is key..
Go a little bit outside the box here: platinum plugs and iridium plugs have more resistance than copper plugs= some food for thought.
Look into champion copper truck plug.
Platinum and iridium are a waste of money.
 
Newoldstock

Newoldstock

New Member
#9
#9
Other things I should have added.

Looking over the list of suggested alternative the criteria chosen seems to cover a very broad range of plugs, some I think are not exactly what I am looking for.

Nothing against the AR3910X I just have no need of it.
I find it fouls easy too.
And its impossible to read for me I do not know what I am looking for ( all I see is black anyways ).

Now BP6ES tells me a lot more, but its a bit hotter than I like and that's why I wanted to buy some cooler plugs ( hitch where do you get a non resistor in that heat range.)
 
N-gin

N-gin

New Member
#11
#11
That dwell thing happens when your coil says go and the resistor says "only at this pace". So what you get is a weaker more drawn out spark.

Usually if you have a resistor in with " high energy" ignitions, the resistor burns out and you coil is now jumping two gaps.

Has anyone here noticed a stripe on their ground electrode and the location of the stripe?
 
vwfan79

vwfan79

Active Member
#13
#13
The plug I use is an AR3923, it's a copper racing plug with a heat range of a BP6ES. I run some high rpm motors and this plug works great and reads well too.
 
Newoldstock

Newoldstock

New Member
#14
#14
Seems to me the original VW air cooled engine used a spark plug that was very close to the spec for the BP6ES ( I think at any rate, seem to recall reading that once ).

Thanks for the tip on the AR3923 I never thought of that ( not a common brand in my neck of the sticks ).
I need to research that, find some and try a few heat ranges.

I suspect I have a preignition problem, not timing related ( although I can not hear it, I see a spot on my piston face that leads me to think something is not quite right )
 
N-gin

N-gin

New Member
#15
#15
If you have preignition that should show as spots on the plug, with would be the aluminum from the piston.
Can you post a pic of the ground electrode? I'd like to see the timing mark on it
 
Newoldstock

Newoldstock

New Member
#16
#16
N-gin said:
If you have preignition that should show as spots on the plug, with would be the aluminum from the piston.
Can you post a pic of the ground electrode? I'd like to see the timing mark on it
Click to expand...
The plug looks fine, the shell electrode looks about where it should.

Everything looks fine.

I just have a peculiar carbon deposit on the face of the piston and I would like to play with some heat ranges.
That I can post a picture of....
 
Newoldstock

Newoldstock

New Member
#17
#17
It will be some time before I get any more engines in pipe so I need to nurse this one into another year.
This block has some history and about 40 hours + one rebuild on it after a wrist pin failure
 
N-gin

N-gin

New Member
#18
#18
If it has detonation it will show on the plug. That is why you are changing heat ranges, yes?
If you don't SE signs of aluminum dusting. I would move on.
That sure is a nifty tool.
How does the bore look? No scaring?
Pic is kind of deceiving, is that above pin circlip? Hot spot you think?
On a side note and you problem already know this heat is transfered through piston rings, sometime thinner is not better.
And engine vacuum plays a big roll in heat transfer of piston rings.
 
Newoldstock

Newoldstock

New Member
#19
#19
Bottom of the bore.
Some mild scoring ( battle scars from this engines racing days ).

I suspect this is very mild heating and maybe some ring lands damage.
It still runs well, limited blow by and no oil consumption.

But the sharp end of the spear is dull now, this engine is getting old and needs to be babied.
A stock plug is too hot for it plane and simple even with the timing backed off to 25.
 
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