Engine Mount Stiffening Modifications

To stiffen up the mounts, two thru-bolts are used to compress the mount.

You will need (4) 3/8"-16  x 1.5" long flat head socket cap screws and 4 Nyloc or Stover nuts.

Drill each mount from the "valley" side so that you can locate the holes about 3/8" from the edge of the ridge opposite the stud side.  

 Use a 3/8" or 13/64" drill bit to go all the way through the rubber and the steel on the other side.  The rubber cuts when the drill is very sharp and kept cool when drilling.

Once the hole is drilled all the way through, turn the mount over.  Use a 90 degree countersink to create a valley  in the steel face deep enough for the top surface of the screws to be flush or lower.

Screw the cap screws through the rubber and tighten the stover nuts to about 15 lbft.