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Gravely 2-wheeler
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What is the appropriate grade bolt for head bolts on a T head Gravely Model L or Super Convertible 7.6 (C8) - Grade 3, Grade 5, other?
 

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What is the appropriate grade bolt for head bolts on a T head Gravely Model L or Super Convertible 7.6 (C8) - Grade 3, Grade 5, other?
I use stainless steel. They don't form a rust bond between the bolt and cylinder head. Don't use a grade 8 because if one breaks, they are very difficult to drill out. Don't use a grade 2 as they will surely bond and break.
 

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I believe that the bolts are at least a Grade 5, however Grade 8 would work fine. The torque on these is quite low and either will work without stretching. If using bolts make sure you give them a good coat of never seize. The ones around the exhaust are the worse.
On the engine/tractor I have been working on (too long) I used studs(high grade) w/ coarse threads into the jug and fine threads for nuts above the head. Used thread locker on the coarse threads and temporarily installed the head and torqued the nuts down to set the studs before the locker set up. Also, if the fasteners get too rusty you can just grind off the nuts and still remove the head without messing up the holes in the cylinder jug.
 

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I used stainless steel studs on Chevy V8 exhaust manifolds --once!--after 2+ years the y-pipe rotted out and all 6 studs snapped off like glass when I went to loosen the nuts,and none of my drill bits would even scratch the remains of the studs,I had to take them to a machine shop,and they used a carbide end mill in a Bridgeport to chew them out..
After that experience I used plain old threaded rod ,at least that can be drilled out easily..

I've not had to work on a Gravely cylinder head,but I'd use grade 5 bolts,they are strong enough,but wont be impossible to drill out someday down the road..
 

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The original spec were probably grade 5 or something cheaper. You only need 20 ft/lb.

I use SS-18 on some of my machines. It looks nice, and won't rust. I've never had a problem with them breaking off unless I over torque them.

+1 on the anti-seize. Get the high-temp (copper) variety.
 
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