Car Nitro & Gas Engines Discuss all aspects of Nitro and Gas rc car engines here!

ofna force .28 head shims


Old 03-19-2017, 08:27 PM
Junior Member
Thread Starter
Join Date: Aug 2015
Posts: 4
My Gallery
My Models
My Feedback
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
rob28x is offline  
Reply With Quote
Old 03-20-2017, 05:54 AM
1QwkSport2.5r's Avatar
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 9,402
My Gallery
My Models
My Feedback

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.
1QwkSport2.5r is offline  
Reply With Quote

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy