Sat Apr 24, 2010 11:04 am by Boots99
With my 4-5/8" Stroked knuck, I found that spacing the motor mount exactly right at the head and the frame attach points was critical to not having them break. They have to be perfectly flat at the points they meet the head and the the frame bracket, and flush against the head. At the frame bracket, I found I needed a thin washer between the mount and the bracket so the mount was not being stressed as it was pulled tight. I also weld small strips of re-inforcing steel on the long runs of the mount, grind all the rough spots down smooth to eliminate as many stress risers as possible, and after welding and or chroming, always "bake" them to normalize the steel. Welding and chroming causes hydrogen embitlement which makes the steel very britle. In aviation "baking" after any form of plating is mandatory for that reason. That seems to have solved the problem for me. A stock engine might not break a lot of top mounts, but with stroked engines, and especially if the mounts are aftermarket, they seem to break a lot. My engine runs very smooth because I had as much carefull balance work performed as possible while assembling it, but it still is a very old 'V' design which has an inherent imbalance designed into it.