ORIGINAL: SeamusG
What I kinda hear you say is ''don't use ''manufacturer supplied'' hardware'' even if it is of the right size and type because it's made of low grade materials. And that your local ACE hardware is an excellent source for quality, stainless or standard materials.
What's your opinion of Dubro's ''black steel construction'' bolts?
That's not what I'm saying actually.
The mention of ARF firewalls was trying to put a perspective on the strength of any bolts and the practice of most ARFs nowadays. They usually have a firewall made of liteply, which is not a good choice for firewalls. And the fact many use only two pieces glued together. Liteply is not made of hardwood, uses only one layer of decent thickness, has only a veneer layer on either side of the one thick layer, and uses a somewhat grainy wood overall.
They often have very strong motor mounts. The iron bits usually are obviously good or obviously bad. Easy to tell if you want to use those bits.
But yes, hardware stores are an excellent source. AND can point you to bolts with a strength that should suffice for sure.
Dubro stuff has been around for a long time and has always been dependable. They certainly have the experience to sell appropriate stuff. If the bag says it's for X-size engine mounts, it's an excellent bet it'll hold that mount to the firewall until hell freezes over. Until I hear they've been sold or taken over, Dubro will always be a trusted name.