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DT wrote:

says...

I am building an engine hoist framework, to hang a chainfall. I will be
using it to pull and install engines and trans in my racecar and other
various vehicles. I planned on using 4x4's for the uprights and the top
crossboard. The crossboard, that the chainfall will hang from, will be
10' long. Is a 4x4 strong enough, or should I use a 4x6, or something
else entirely? I figure the engine/trans combos shouldn't be more than
700 or 800#...

A 4x4 will definitely not be strong enough.

Depends on the span, no? If M = WL/8 = 100L and S = M/1000
and 3.5 = sqart(6S/3.5), L = 71" max, approximately.

Nick