When to shim and not to shim
10-05-2003, 10:30 PM
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When to shim and not to shim
How do I know when to pun in or remove shims on my engines? I have been doing this for a while. I consider myself an intermediate RC hobbiest. I feel comfortable tuning my engines properly and would like to do more advanced tuning.
10-06-2003, 04:22 AM
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RE: When to shim and not to shim
a shim is a dividing peice of metal imbeteen the crankcase and the body the bigger the area imbettwen the crankcase and the head there is the less compression or vise versa but im not sure of the logistics of it ? Hopes this helps 
10-06-2003, 01:03 PM
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RE: When to shim and not to shim
Put in between the head button and the head, shims lower or raise your compression ratio of the motor.
The less shim, the more compression, the more power, the more your engine gets stressed, the shorter time the motor lasts.
The more shim, the less compression (more air:gas), less power. less stress, lasts longer.
If you run 30% fuel some engine manufacturers say to add a .10mm or .20mm gasket to lower the compression to accomidate the higher nirto combustion.
Also, Some manufacturers put more gasket in the head than they need to, strictly for longevity and they are not all needed. It is not a good idea to take out shims unless the manufacturer says it's ok to do so.
Hope this helps
The less shim, the more compression, the more power, the more your engine gets stressed, the shorter time the motor lasts.
The more shim, the less compression (more air:gas), less power. less stress, lasts longer.
If you run 30% fuel some engine manufacturers say to add a .10mm or .20mm gasket to lower the compression to accomidate the higher nirto combustion.
Also, Some manufacturers put more gasket in the head than they need to, strictly for longevity and they are not all needed. It is not a good idea to take out shims unless the manufacturer says it's ok to do so.
Hope this helps
