Vernier Isolastic adjustment

The instructions included with my set required a 10 thou feeler gauge to be inserted between the plastic disc and tube cap. You should try and find the instructions.

If you don't have the magic switch off at 2500 rpm or any rpm then look for something rubber mounted touching something not rubber mounted. The Hemming's vernier is just a way of converting old rubber mounts to vernier adjustment, if you have also changed the rubbers then they probably are not Hemming's vernier but the std MK3 vernier and some of these full kits have hard rubbers which increase the vibration and move the vibration higher up the rev range. So check to see what you have, there are differences between the 2 types. I have old rubbers that have the magic switch at 2500, they are never going to be replaced unless they disintegrate, the are coated in silicone grease to preserve them.

There is quite a noticeable variation in these Verniers Kits depending upon manaufacturer. My first set was from Norvil and the recommended gap setting was half a turn of the adjuster from fully closed. The engine vibes were unchanged but the handling became poor. My second set were from Andover Norton. With these the adjustment was just less than a quarter turn from fully closed.....plus it was suggested to me that the engine be held over to one side before making any adjustment. I gues this was to eliminate any slack in the set-up. The handling was much better but the engine vibes horrible below 3000 rpm.

I have also seen the tube end caps installed backwards (cupped surface out). Adjustment is not possible in that situation.