Some folks like to put threaded brass inserts flush (actually leaving them a little "proud", then sand them flush) to the engine side of the bearers, thus letting the engine lugs sit direct on the brass. That way, the wood isn't compressed, which is true enough. But does it absorb the vibes as well?

I'm more inclined to put the threaded brass inserts (better yet, Keen-Serts) on the far side of the bearers from the engine, but face the bearers with aluminum (or epoxyboard, phenolic, etc) pads at least 1/8" thick and at least double the length of the engine's mounting lugs.  Idea is to spread the load, and thus not compress the wood, yet make the bolts stay tight and under tension via the natural "give" in the wood.

Which notion is better?  Let the arguments begin...but be nice! Steve   

I've done it both ways without issue. Putting the engine on pads seems easier to me, though. Keep in mind I don't have experience with 60 sized stuff, but done a bunch of 40's.

I have used both brass inserts and blind nuts on the far side of bearer with 3/32 or 1/8 phenolec pads under engine lugs.  Either one works good, but for me the blind nuts are easier to install.

To my mind if the engine is prone to crushing the bearer then the mounting lug's area is too small, but there is not much that can be done about the engines design itself.
(Just take a look at PAW's engine lugs, nice and long and never a need for extra padding or inserts!)

I personally don't like the look of inserts as I want as much hardwood in that local area as possible and much prefer engine pads to spread the love where necessary.

Thanks.

Hope this does not sound like a dumb question, but what are the advantages of the brass inserts over other methods such as the blind nuts?

Tx.

Mike

If you tourque down blind nuts to 5.000 Ft Lbs youll end up with 1/2 x 1/8 bearers  or theyll get all pulleed outta shape.

 Brass or Whatever INSERTS , IF right through , remove the CRUSHING load of the tension in the bolts .From the Bearers.

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As in the inserts are bottomed against the Lugs or pads. If done right.
Putting tube in oversize holes throught to the T nuts could work.If Tarzan does'nt tighten the bolts.

Pads are larger than Lugs, so at the same tension the Lbs / Sq. In. are less.

Cunning Swine even select there BEARERS for excellent grain, and hardness.
Hart timber (from the core of the tree) and sap timber (from outer reqions of trunk)
are considerably differant densities. As are trees from differant spots. on hills.
Shade watering etc etc.
Dense bearers are ordinarilly heavier , so we can see why some people drill lightening holes along them.

Though in the old days some people with motorcycles just had too much time on there hands, and a drill press.
Hence the term ' Swiss Cheese ' used to describe the results of their endevours.

Regarding Chris' example above, would anybody be concerned with the wedging action of the flathead screws 82 degree angle splitting the bearers? I would not be (because the hardwood beams are tapped), but the thought did come up. I would definitely prefer to use a hex wrench in a socket headed cap screw to messing about with a nut driver in cramped quarters.  It appears that there are several solutions that work fine, but there are some theoretical "issues" with each that need to be decided upon.   Steve

I cut my own engine bearers from rock hard maple.  Oversize, usually 5/8 X 5/8.-  Behind the firewall, I taper them back to `1/8" at the 10" or 11" mark.  Saves weight, but provides plenty of meat at the engine.

Floyd