Putting the shim under the sleeve will increase exhaust and transfer timing. It calleds "field modding". It is not working all the time-in both ( exhaust and transfer events ) it will be encrease equaly, but it is not always right.
Chnages are about 0.1 mm shiming is equal 2 degree of timing on 12 engines ( strock 14 mm and rod 25mm), if strock or rod is different, that will be different. So for Novas based engines .1mm shim-2 degree timing. If anybody needs this numbers, please give your's engines data and I will give you how much timing will chnge with .1mm shimming.
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