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ofna force .28 head shims

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Old 03-19-2017, 08:27 PM
  #1
rob28x
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Default ofna force .28 head shims

how many head shims should this engine have 2 or 4 the manual diagram shows 2 it had 4 when i took it apart i got this engine in a large lot of R/C parts and several buggies i found lots of things not put together correctly on 2 Traxxas Revos so i am wondering if the head shims maybe wrong also
i have resealed this motor cleaned and lubed it factory carb settings hsn 3 turns lsn flush it will start but will not run for long or die when i remove the glow starter {rich condition?} i can lean the hsn about 1 turn and it will no longer start also i can lean the lsn about 1 1/2 turns and it will no longer start i am now wondering if it has double the head shims if it is lost to much compression i will try and remove 2 and see what happens
just looking for some insight into this
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Old 03-20-2017, 05:54 AM
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1QwkSport2.5r
 
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Shimming the head lowers the compression. Measure the head clearance and shim the head so you have .4mm head spacing (about .015"). Most often this will require 1-2 shims of .1mm-.2mm each. You should measure first and shim last. Too much head spacing will leave power on the table unless you use gobs of nitro in the fuel.
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