ORIGINAL: dbacque
Sand it first, then epoxy or CA will stick to it fine.
Dave
Ditto...
Fit needs to be tight, so if you have to make the hole larger to allow a straight run for the throttle cable, make a doubler of 1/8 thick ply with a tight hole in it - CA to firewall over the larger hole. The doubler method also works well to stabilize a long run of nyrod..
Cheers!
Jim