A few quick pictures on how to easily install a header tank on your Caliber 4.
Use one of the hex standoffs available from Kyosho PN CA3069 --
Remove the upper rear self-tapping screw from the frames that's located just above the tank.
Drill the hole out using an 1/8th inch drill to provide clearance for a 3mm hex head cap screw.
Insert the hex standoff into the right side as shown below:
Insert a 3mm hex head cap screw through the hole that you drilled out, and make sure it's long enough to thread into the end of the hex standoff. Tighten the cap screw to secure the frame halves together, and to hold the standoff in place (use a bit of blue loctite).
Install the header tank on the end of the standoff (blue loctite again).
Voila, a nice, solid header tank mount in about 5 minutes!
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