The title of the thread is Head dowl? Are they important?, and the answer is absolutely! Chris, they do help to keep the head and gasket centered during installation, as you know, but they also help keep the head in place afterwards, too. The bolts by themselves do not automatically line up the head correctly. There is play around each bolt as it passes through the head. The bolts do 95% of the job of holding things together, but the dowels do their 5%. How do you know when you're torquing the head bolts down that the head is perfectly centered? It's kinda like saying the crankshaft key isn't necessary because the dampner bolt will hold the dampner place. Kinda. That's a little extreme, but I hope you get the point.
An engine can be assembled and run without the dowels, but it would be very foolish, and risky, to do so.
Take care,
~Chris
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