I only have 3-1/2" and 4-1/2" bolts left

Why goof around with using steel washers that are not all the same thickness. Here is a quick an simple way of spacing out your motor. The base stand off is precision machined from 6061-T6 aluminum. It measures 1" diameter at the base to give a good load bearing on the wood, and necks down to 5/8" in diameter at the motor and has a 1/4" thru hole.  If more length is required, simply add the spacers included to get the desired length up to 7/16" of added length. Kit comes complete with (4ea.of the following) Stand off bases, plus 4 ea.)1/4", 1/8" & 1/16" boss extensions included.

Bolting everything together is alot stronger than threading the stand off and having a bolt at each end.  Besides with a bolt thru you only have 4)bolts to tighten

Available in 5 popular lengths

1/2-15/16"

1 to 1-7/16"

1-1/2 to 1-15/16"

2 to 2-7/16"

2-1/2 to 2-15/16"

1/4-20 Socket Head Cap Screw  Alloy Steel  /  4 bolts per package

Available in Popular sizes

1" thru 4-1/2" by 1/2" increments

Minimum of 1" of thread

Length of bolt is measured from under the head to end of thread (tip)

Bolts are non returnable