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Update: I finally stopped using the 'feel' method for injector timing and it fixed a whole shop's worth of problems
For years, I was taught to time injectors by feel, lining up the marks and then giving the pump a little nudge 'until it felt right.' I did it on everything from old 7.3s to newer Duramaxes. The tip off was a 6.7 Powerstroke that came in from a fleet in Boise. It had a rough idle and low power, and I'd timed it myself three weeks prior. My boss had me put a timing light on it, and we were off by almost 4 degrees. That small number explained the whole job. I realized I'd been trusting my hands over a $200 tool this whole time. Now I clock everything, no exceptions. Has anyone else had a basic shop practice fall apart under simple testing?
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lane.cameron9d agoTop Commenter
Calling it a fluke is how you get three trucks back in a week. That "feel" method drifts over time, especially as pumps wear. I've seen guys be dead-on one day and then be 2 degrees off on the same engine model the next month. Your hand can't feel the difference between 1.5 and 2.5 degrees of advance, but the engine sure can. It's not worth the comeback.
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fox.derek7d ago
We had a fleet guy at the old Miller yard who timed by ear for twenty years. He swore it was perfect. We put a light on six of his trucks one afternoon and not a single one was inside the spec window. The oldest was a full four degrees retarded. You just can't trust the seat of your pants on something that exact.
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