How do I switch an 8.25 Small Bolt to a Big Bolt pattern?

Beware of adapters in cases where the welded weights on the drrum interfear with the adapter as suggested in the picture above. The adapter must sit flat or it will work loose.
To grind clearance in the adapter or grind away some of the weights is often required.
Adapters got a bad reputation years ago because they weren't properly installed.

i had a pair of those cast aluminum trans dapt adapters. those things cracked on me in the first month i had them on and they were perfectly flat on the hub... total junk IMO. the billet aluminum adapters are the only way to go if one must use them.