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Fitting Cox .049 pistons to cylinders..

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Re: Fitting Cox .049 pistons to cylinders..

Post  Oldenginerod on Mon Jun 26, 2017 4:04 am

Roddie. I know you said the screws tightened up ok, but I've found when removing the choke tube from a Surestart backplate that my screrws bottomed & needed shortening, or a washer under the head.
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Re: Fitting Cox .049 pistons to cylinders..

Post  MauricioB on Mon Jun 26, 2017 4:21 am

Roddie, I've got one of my engines in that way.

To screw, you must remove the cylinder, screw it in and then replace the cylinder.
To prevent a screw from passing, you must place in these holes, these servo rings Du-Bro. Thumbs Up


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Re: Fitting Cox .049 pistons to cylinders..

Post  roddie on Mon Jun 26, 2017 9:27 am

Thanks fella's.. good tips! I like the servo-mount inserts Mauricio! Thumbs Up My airplanes almost all have firewalls drilled for mounting the backplate for the fuel-line to be on the R/H side where I usually have a wedge-tank. This keeps the fuel-line as short as possible.

I really don't know why I chose to orient the cylinders "upright" on all six engines.. and I'm going to re-orient them all to run outboard. I honestly don't want to remove the cylinder to mount an engine.. plus; orienting it horizontally helps to protect it in a crash.

This triplane had its cylinder mounted "inboard".. when I flew it 25 years ago. It had balance issues (tail-heavy.. affraid ) so it only flew once.. and crashed.



The damage was minor and I've made some modifications.. but haven't flown it since.



Those top/bottom wing-flaps have been removed, saving .4oz. of weight behind the C of G.





I'll orient the cylinder outboard this time when I try to fly it. Those were the early days when I knew even less than I do now.. Laughing
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Re: Fitting Cox .049 pistons to cylinders..

Post  roddie on Mon Jun 26, 2017 8:39 pm

One more time.. Rolling Eyes (humor me please..) Back-plates have been re-oriented for mounting all-four screws to the firewall with a horizontal outboard cylinder configuration. (What a maroon.... Bugs Bunny..)




See that stubby screwdriver? OCD Roddie likes its' ratcheting function. I start each screw by turning it "out" until I feel the screw-threads engage with a "click".. then I tighten each a few turns. I do this to all four screws until they're close to seating. Then I set the ratchet-driver in reverse to act as a "clutch". When the ratchet clicks while tightening.. I switch to a diagonal screw in the pattern. When they all "click".. I switch-off the ratchet and tighten gradually in the same alternating sequence.. (the way I was taught to change a car tire..) without being too heavy-handed.. After all they're only 2-56 size screws.. The PH1 insert-bit fits these screw-heads nicely. The case-screws were sourced from Cox International (Bernie).. as were the back-plates.

The short-style needles and Mylar reeds were sourced from ExModel engines (Matt). I have a few long-style needles.. in the event that I want to try a choke-tube. The short needles are too short to work with them.
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