TIL I've been setting valve lash wrong on my old 7.3 Powerstroke for a solid year.

I was watching a guy on YouTube rebuild a 12-valve Cummins, and he mentioned checking lash with the engine at full operating temp, not just warm. I'd always done it after a 10-minute idle. Grabbed my feeler gauges and checked my truck hot, like after a 30-minute drive. Every single exhaust valve was way too tight, some by almost 0.002. I guess I was just following what the old guy at my first shop taught me. Is checking lash at full temp the standard for all you guys, or is this just a specific engine thing?

3 comments

3 Comments

daniel_martinez842mo ago

That old guy at your first shop had you checking lash 0.002 off on a hot engine. I can't believe that method got passed around for so long.

wyattbennett2mo ago

Worked fine for decades, man.

blake_martinez11d ago

Ngl that method is wild, I had a guy swear by setting valves cold but then adding 0.004 for "thermal growth" like it was gospel or something. Tbh I wasted a whole afternoon once trying to chase down a tick on a 350 because the old book said to check them hot and loose. Honestly feels like half those tricks came from someone guessing and everyone just ran with it.