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Old 10-07-2011, 06:41 AM   #1
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Head stud warning

Head stud warning

Just a friendly warning about the use of head studs instead of bolts on the Mercury race engines.

I have a Drag motor that arrived for me to build going on an F1 boat in Australia, after inspecting this block I found a hole in the exhaust port behind a head bolt boss which indicated that head studs were used. My guess that the studs were ran up with an impact or no consideration was taken for the lack of thickness behind this boss being so close to the large exhaust port.

I have a highly ported steel sleeved motor at my shop with all six exhaust ports in alignment with these bosses have holes punched through because of a careless instillation of studs...

Good luck,
Jay
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Old 10-07-2011, 09:09 AM   #2
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Any pics Jay ?
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Old 10-07-2011, 01:46 PM   #3
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No pic I'd have to stand on my head LOL...

The only thing you could do to keep from pushing a stud thru a thin exhaust port is to use a measuring devise ( I use a caliber with the tee end placed in the bolt boss flat against the deck and touch the bottom of the boss ) this will give you an idea where the boss ends. This thinness only happens on 6 of the 24 head bosses..

I find large ported motors where lots of material in the exhaust port is removed are more at risk.

BTW: A hole in the exhaust at the points I described will NOT yield the motor unusable its just something that can be avoided with a bit of care and awarness before instillation ...

I don't care for nor will I use studs in engines I build from scratch I use bults BUT when decked blocks, thin head gaskets and shaved heads come into play I even measure the head bolts to protect against block contact as well as bottoming out and prevent total seal of the head gasket...

Just a FYI for those interested...
Jay
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