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Old 02-18-2021, 10:33 PM   #1
alexiskai
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Join Date: Apr 2018
Location: Mebane NC
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Default Stud boss height for stock heads

I'm doing some research for my cylinder head install video and I'm interested in what people say about installing the studs. Notably, some folks say you should hand tighten the studs in the block and then back them out one full turn (Rich Fallucca of AER says this, you can watch him say it right here).

Fallucca goes on to say, "this gives you about one and a half threads above the top of the nut. If the studs today are screwed all the way down into the engine block, and you put the nuts on there, the top of this stud will be about a thread and a half below the top of the nut. We're looking to have it about a thread and a half above the top of the nut, so we unscrew the studs. It won't hurt anything."

This confused me. Are "the studs today" shorter than the OEM studs? This seems relatively easy to fix. But then someone suggested to me that the actual problem is that many HC heads are taller than the stock head, measured at the height of the stud boss above the deck. I don't have a collection of HC heads, so I can't check this.

Bottom line, I'm trying to give good advice to the folks watching the video, some of whom may have out-of-spec heads. What I'd like to say is something along the lines of "If your stud boss height is greater than X, you'll need to unscrew your stud one turn to ensure you have adequate thread engagement on top."

Does anyone know the spec for the height of the original head as measured at the stud boss? Anyone know whether the popular HC heads like Snyder's are taller than the spec? I know they're under-size in terms of overall length.
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