Bolt strength
 

I bought engine stand for 1.8 Miata motor.
The bolts I bought are
12mmx1.5x120 8.8 class
12mmx1.5x100 10.9 class
Are these strong enough for a 300lbs motor?
Thanks.

Real answer, is depends on a lot of geometrical factors, the engine is canti-leavered off the side of the stand and the bolt spacing and effective moment arm of the motors cg changes the stress in the bolts

The practical answer is an m12 8.8 is good for something like 25 tons of tensile force. unless you have something crazy going on the bolt itself is not goning to fail

Are the bolts in shear or tension?

Yes.

Also, no need to tighten much - just adds to the stress.

Thanks everyone.

How many volts are these bolts?

http://forums.pelicanparts.com/uploa...1714773958.jpg

^ is that from Mr. Mom?

Some of both.

I always use grade 8 3/8s bolts for my big block chevys on my engine
stands. Never an issue

Not sure what the metric equivilent is..