Another little sparkplug factiod, use a smaller gap when upping your compression.

 

This is the Best post I've seen in a while![img]i/expressions/face-icon-small-smile.gif[/img]

There are still guys here in the know and willing to give some valueble Info.[img]i/expressions/face-icon-small-happy.gif[/img]

UBETRUN, Good info Couldn't have said better myself.[img]i/expressions/face-icon-small-cool.gif[/img]

 

UBETRUN Does the postion of the ground strap have any bearing on flame propagation ? Should it be at the back side of the intake flow? just wondering if you had read any on ground strap postioning?

 

In adding....the reason for this is that the higher compression has more push force against the spark crossing the plug gap. Try walking into a 50mph wind and then into a 70mph wind...same difference.

 

I you are concerned with the heat being put into the porcelain, why would it be improper to use the porcelain as an indicator? I ask because every automotive manual I have recommends reading the plug by the porcelain as well as by the ground strap.

~HoundDog

 

Hound dog,The strap will indicate whether or not the heat range is correct.The porcelin and flat above the threads will indicate jetting issues.The tip is going to see the most direct heat.A strap thats burned too close to the base indicates the heat is being transferred too slowly(plug too hot).A strap thats only burned at the tip indicates the heat is being transferred too quickly.(plug too cold)

Optimal is when the strap is burned about half-way.Standard heat ranges will work best on machines with stock compression/timing etc.Anytime you bump up the compression or run a power adder(nitro,turbo,alky),a cooler plug should be considered,not to mention a tighter gap.

 

Outlawlanwndragster - You are asking about plug indexing. The idea behind the practice is to keep the ground strap from shielding the A/F charge from the spark. I index my Raptor plug by centering the ground strap between the exhaust valves. I don't know if it helps or not in the Raptor head but it can't hurt.

HoundDog - You CAN use the porcelain to read gross jetting (if the heat range is correct) but the most accurate method is the base ring and/or where the porcelain meets the metal plug body. Most folks don't have a little hand held microscope so they just use the porcelain. Once you get jetting close to "too lean", the porcelain will not show any color and you will have to read the base ring and/or base of the porcelain.