Correct Spark Plug Gap on 3.5 EB
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From: ME
.028 or .030 will both work fine on a stock truck, but .028 is better if tuned, less chance of blowing out the spark under high boost.
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The tighter gap made a big difference in how smooth the engine ran with a Tune in mine, and after a close inspection of the stock plugs with only 30K on them, the pit in the ground strap was enough for me to want to go smaller to get more life out of them.
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Senior Member
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From: ME
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From: MO
Gen 1 works best with .027" gap, especially with a tune. The Gen 2 will be good with .030" gap. Since the Gen 1 is Direct Injection only, like a Diesel engine, the smaller gap gives a better spark to help with ignition in the high pressure cylinders. The Gen 2 has DI and MPFI, the latter more conventional, and only runs DI under heavy loads, so the gap isn't as critical.
One other thing to note, the plugs use a very fine center electrode, and will eat a hole into the ground strap, which effectively increases the gap over time, which is why going to the .027" gap helps with a tune. When pulling a high mile plug from the EB, grab a magnifying glass and look, the crater is quite impressive.
One other thing to note, the plugs use a very fine center electrode, and will eat a hole into the ground strap, which effectively increases the gap over time, which is why going to the .027" gap helps with a tune. When pulling a high mile plug from the EB, grab a magnifying glass and look, the crater is quite impressive.
One thing I CAN agree with is your statement of the quite impressive crater in the ground strap. I was amazed how deep it was after 34k miles and can't imagine how deep it would be if someone tried to wait until 100k miles to change plugs.