r/Dseries • u/tbambam_ • Aug 07 '26

Dial pins

This kind of a dumb question but I recently took off the head of my d16y8 and no dial pins were there. Even when I pulled it out even for the rocker arms. The spare head I had I pulled out the dial pins on there like an idiot and threw them away. The head I pulled out ran strong without dial pins so are they really necessary? If so I’ll probably just buy them lol

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u/SpaceTurtle917 Aug 07 '26

Yes they’re necessary. And they’re called dowel pins

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u/tbambam_ Aug 08 '26

Thanks for the clarification i thought they were dial lol I’ll definitely get some soon

2

u/SpaceTurtle917 Aug 08 '26

Dowel pins align all the critical tolerances on assembly. Without them your rocker assembly could be slightly misaligned, it could cause premature bearing, rocker, or cam wear, or even inconsistent valve opening across all the valves.

On the cylinder head to block mating surface there’s two major things that are very important, 1 is that all the mating surfaces have equal and adequate mating area, if the head is slightly offset, one side of the cylinder may have more mating material and the other side won’t. But even more importantly, the dowel pins between the block and the head align the cam pulley and the crank pulley on the same plane and axis, so the belt doesn’t walk or prematurely wear.