posted
Roddy you asked me the other day for any suggestions. Heres one could you post a sticky shim guide. Adress what shims do as for as compression or adding power or taking away power. It was one of my questions and I have seen it a few times. A guide would help with the redundent post for shims. You may have already done this but I can't find it in the FAQ area.
Engine type Fuel % # of shims
Posts: 7 | From: Charlotte, NC | Registered: Jul 2008
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posted
I personally think creating a head shim guide would be difficult to do as there are way too many variables that go into head shims. Doing this may have people removing head shims and actually damaging their engines. Head shims should only be used if you are really good at tuning and if thats the case you probably already know about head shims for tuning purposes.
for example.... the engine comes shimmed to run 25% nitro at sea level. In my case I am at 5000 feet above sea level so I actually run 30% with the thin head shim removed so I only have one in there. If I run the engine like this I have to run a number 6 plug, if I go any hotter on the plug I will see some signs of pre detonation. As the engine gets older and gets to the 8 gallon or so mark I generally remove the thick head shim and run just the thin headshim. I have been at sea level before and on a new engine I was able to run 30% without the extra head shim but this is takin a chance by doing this.
There are just soo many different variables that go into playing with headshims that having a chart would be tough to do and could lead to inexperienced users removing head shims and damaging their engines. I suggest you do some reading on these engines and how they work and go from there. Also rather than doing anything with headshims try different plugs to start with.
posted
xtracy, Thanks for the suggestion and as cperalta explained it will be quite hard to make a chart like this with all the possible variables interfearing.
Untill now we have always supplied the engines with the headshims for 25% nitro in general and this has not caused major problems, however if you wish to go further then things become quite hard to explain due to the different variables mentionned by cperalta.
If the engine is working fine for you then this is already good and you can concentrate on the driving and your chassis setup. Of course you can always try thing and we will do our best to explain but too many things can go wrong and we prefer not to make things too complicate as they can become sometimes.
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