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what grade should engine support bolts be ?

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Old 03-10-2007, 06:39 AM
  #31
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http://www.arp-bolts.com/Tech/TechMetals.html
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Old 03-10-2007, 11:48 AM
  #32
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If JC built your motors i guess a couple of 10-24's and some wing nuts ought'a do it
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Old 03-10-2007, 01:12 PM
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High school graduates or GED equivalent?...
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Old 03-10-2007, 04:18 PM
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Quote:
Originally Posted by AppSysCons View Post
Do not use stainless for engine mount bolts! The sheer strenght of stainless in fairly low, the will fail. Use Grade 8 carbon alloy steel, look for 6 hash marks at the points of the hex bold head.
Yup
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Old 03-10-2007, 05:07 PM
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Guy's reading this thread are you talking....
L-ANGLES TO CRADLE MOUNTS
CRADLE MOUNTS TO ENG. BLOCK
L-ANGLES TO STRINGERS
or all of the above? I used Grade 8 on just the cradle mounts to the Eng. Block and SS for L-Angles to Cradle Mounts and Stingers, But I only have Small Blocks not the Big 630cu in like you big dogs run. Am I ok that way?
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Old 03-10-2007, 05:16 PM
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Cuda is right. Grade 5 is a better choice in this case. Grade 8s are stronger if all surfaces are machined and the bolt is in pure tension. If the surfaces are painted and possibly not 100% square, grade 5 would be stronger/tougher. It is more ductile and forgiving of uneveness of surfaces like you would see in generic motor mount applications. Grade 8s are for perfect clamping situations like a head to block.

Many years ago I was an engineer at John Deere Tractor Assembly in waterloo Iowa. The plant was highly automated and most handling systems were underhung from the trusses of the superstructure of the building. The engineer that installed the overhead cranes and such used grade 8 bolts to toe clamp the bottom chord of the trusses. The bottom chord of trusses are somewhat angled. After a few years of operation we started to find broken bolts on the shop floor. The grade 8 bolts were snapping!! Not good with engines and transmission moving over people!!. Anyway, all the bolts holding the cranes up in the 2 million square foot factory had to be changes out to grade 5 bolts. Grade fives can take the load and be forgiving of uneven surfaces. Many an engineer has made this mistake.

BT
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Old 03-10-2007, 05:32 PM
  #37
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My boat was rigged with SS from the L-angles to the stringers. There are 6 (3/4") thru bolts in the center and 3 (3/4") on the outsides. Steel on the offshore mounts to the engine block and steel from the offshore mounts to the L-angles.
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Old 03-11-2007, 09:09 AM
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Quote:
Originally Posted by Panther View Post
My boat was rigged with SS from the L-angles to the stringers. There are 6 (3/4") thru bolts in the center and 3 (3/4") on the outsides. Steel on the offshore mounts to the engine block and steel from the offshore mounts to the L-angles.
That's exactly how you want to do it
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Old 03-11-2007, 12:44 PM
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I use Gr8 in all the high- stress applications and coat them with KGI Gunkote. If you do, you must use a lockwasher and torque them. The Gunkote has moly in it.

Applications-

Mount thru-stringer, plate to mount, plate to motor, accessories, bellhousing, starter, accessories, etc.

My local Lowe's has a big selection of Gr8 but the one down the road doesn't. The quickest way to get them is McMaster-Carr. www.mcmaster.com
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Old 03-11-2007, 05:04 PM
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Most farm/tractor supply stores carry a good assortment of grade 8
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