Iridium plugs are not plated. That is a solid electrode. The diameter is much smaller and so more easily damaged. So it is recommended to exercise care in measuring the gap and reduce the possibility of applying lever force to it using a feeler gauge.
The gap is important. Too small is almost as bad as too large. The coil will build voltage until something breaks down and arcs. You want that to be the spark plug. If the gap is smaller than designed, the coil voltage will be lower when the arc happens and so less energy in the spark. Too wide of a gap and you risk damaging the coil by exceeding the designed voltage the coil can withstand.
I use the specified AC Delco iridium plugs, gap set at .060" in my GM cars.
I always check the gaps before installation, but seldom, if ever, have to correct them. The plugs are packed in their individual boxes and have plastic sleeves (tubes) slipped over the threaded portion of the plugs and extending beyond the tips of the plugs to protect them. It works.
If it workedā¦then youād NEVER have to adjust them. I agree that it has helped tremendously. I rarely see gaps that are out of spec. But it does happen. And based on a little data sampling from a small sampleā¦Iād say itās well over 5% of the time. Statistically - 5% is HUGE. Six-sigma would like to see less then .1%.
I finished doing all of the work to the truck, and started it up today, and let it run for a long time in my driveway to check for leaks, etc. It started up after only a few tries (normal, since I replaced the fuel filter) and idles smoothly. I still have the front end raised, because I am trying to purge all the air out of the cooling system (I replaced the radiator, expansion tank, and all hoses).
Everything seems ok, however I am concerned because the passenger side tank of the radiator, and the lower radiator hose barely get warm. The heater hoses get hot, the heater works, the upper radiator hose gets hot, and the cooling fan runs, blowing hot air over the engine. The temperature gauge reaches 201-203, but it appears the thermostat never opens? The water pump was replaced recently, as it looks shiny and new, so I did not bother replacing it again.
Top rad hose wouldnāt get hot if the thermostat didnāt open.
Cooling fan is doing itās job: cooling the coolant by the time it reaches bottom of radiator.
