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Advantages/disadvantages head bolts vs. head studs


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With the noss head that I run I have had some issues with the copper washers. I purchased vittos acorn nut kit. However they squish so much that they compress onto the studs. This makes for a very difficult head removal. Are there any disadvantages to running a head bolt with a flat flange? One can just use a lil silicone to seal the flange to the head to seal the coolant chamber. This would make a head removal much easier.

Edited by turbowrenchhead
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The copper washers are really only there as a fail safe. As long as your O-Rings are all good there will be no water to leak out of the nuts. I have ran plenty of motors with no copper washers under the nuts. 

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I personally was curious why one needs the acorn nuts with NOSS style heads vs not needing them with a pro design even though both have pretty much the same design for orings around the studs. In my belief it's due to most people running the noss head use their oem studs which do not have a stepped up center section and have no more than a single thread edge or nothing contacting the oring to prevent the upward flow. the pro design studs and even the arp studs that I'm using have a longer and larger diameter center section that makes a seal against the oring to prevent upward flow of the coolant through the threads.

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ive got various engines. some have studs and others have bolts. never had a problem with either one

were they always bolts? Or was it designed with studs and you switched to bolts? As your aware bolt pattern/spacing and thread depth, along with head rigidity would all factor into your ability to maintain a good seal.
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These cylinders I have now are at 66mm and they won't have a long life on the bike. I think I'm going to get some bolts today. My Noss head doesn't have seperate o rings for each stud. Just the main o rings for the head to seal it off from the dome and atmosphere. There are only two studs that are outside the main o ring that are not going through the coolant chamber.

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