Adjusted injector timing with a dial indicator instead of eyeballing it, actually worked

I've been turning wrenches for 8 years and always set timing by feel, never trusted the whole dial indicator setup. Last month on a 2007 Cummins in Nashville I finally took the time to mount the indicator and do it by the book. Took about 90 minutes extra but the idle smoothed way out and the engine lost that cold start rattle. Maybe it's just me but I'm thinking about doing this on every truck now, even the older ones where I thought I had the feel down. Anyone else switch to precision tools after years of going by ear? What did you notice different?

2 comments

2 Comments

norab2117d ago

Tbh the "backing it off a few degrees" part hit me. That's the real lesson nobody talks about. Stock specs are a starting point, not gospel, especially if someone's messed with the pump before you. I've seen guys chase their tail for days because they trusted the book over what the engine was telling them. Dial indicator just gets you in the ballpark, then your ears and the pyrometer finish the job. Ninety minutes extra beats redoing it twice, every time.

cole99418d ago

You got me thinking about my old 7.3 work truck, did the same thing last winter and it was night and day. That cold start clatter you mentioned, it's usually the timing being off by just a hair, even if it feels right. I always thought the dial indicator was overkill too, but now I use it on anything with a pump that I'm not 100% sure about its history. The extra time is worth it when you don't have to go back and redo it a week later. One thing though, make sure you're using the right base timing spec for the mods on the engine, not just the stock number. I found that out the hard way on a mild build, ended up backing it off a few degrees and it ran even better. Keep doing it by the book, your ears will thank you.