FE,
You are correct. (4) 5/16" studs in tension can handle more than double the load of (2) 3/8" bolts in shear. (given that they are made of the same grade of material)
The studs used in the testing were ARP. After breaking the lift plate at nearly 9000lbs, the studs could still be removed from the aluminum manifold by hand. I was surprised by this. I suspected that the studs would pull out of the manifold before the plate failed. I used an aluminum Edelbrock BBC dual plane manifold in the test. It survived the testing and shows no visible signs of stress.
I designed the features into this plate for several reasons. For one, I could not find a lift plate that had all the carb bolt patterns (4500, 4150, 2300, carter, q-jet, 2 bbl rochester) on one plate. If you are working with various types of engines, a TRULY universal plate sure makes life easier. My dad uses my prototype installing and removing engines from the dyno. So no matter what carb the application requires, he's got it covered. Also, I incorporated a swivel eye to eliminate chain binding and so you can work on the engine while it is hanging from the hoist,(flexplate, mounting brackets, etc) without tripping over the cherry picker legs or banging your head on the boom. You can effortlessly bring the work to you. And finally, the load leveler reduces the amount of man handling required to get dowl pins lined up or disengaged. Between not fighting chain bind and not needing a 3 foot pry bar, my engine compartment paint sure has fewer scraps and nicks. I also reduce bloody knuckles and my language has cleaned up a little. : )
Take care guys.
Chris Cogan
www.kaizen-ms.com