GP 42 manual/tuning procedure

Hi all,
I have a slightly used Thunder Tiger GP-42 that I am putting in place of
my OS-32SX on a old (now disposable) airplane. Long story but let's just
say I don't expect it will be flying much longer and the 32 is far to good
an engine to put in harms way! I've never run a GP series engine before and
I believe it uses an air bleed type carb, not the twin needle arrangement
I'm so used to. Anyone have the manual and could scan me the relevant
sections or fax them to me? (US/Indiana number) Or if you are familiar
enough perhaps you can give me simple directions on best tuning procedure?
I'm sure the engine is well broken in but doubt much it is tuned very well.
I'll be ready for run up in a couple hours so just getting a jump on the
learning curve before I frustrate myself.
Reply to
Jack Sallade
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refer to = Engines,Plugs,Tuning, Petrol, Turbines, Mufflers, Cleaning, Anodising etc sub section: Carburettors, Tuning & Performance Testing, Glow Plugs. at =
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pictorials on tuning carbs etc. In need, email direct for copy of Thunder Tiger Engine Instructions sheets/Manuals. regards Alan T. Alan's Hobby, Model & RC Web Links
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Reply to
It's an ABC engine, just like the .32, so the break in technique is about the same. You set the high end the same way. For the low end, instead of metering fuel, you are metering air, so you turn it the opposite way to achieve a rich/lean setting. Turning the air screw out adds more air by uncovering more of the bleed hole, thus leaning the mixture. Out=lean, In=rich. Make sure that the bleed hole is free of obstructions. The GP .42 with a mousse can pipe is actually a very powerful engine, more powerful than a .32, and does wonders on a .25 size 3D model. Without MCP, it's still a good runner, way better than an OS .40LA anyway.
Reply to
Frank Costa
I started with a slightly used GP42, great running engine. I flew it for over a year before I replaced it with a 46 pro. Until I read the post above that you could adjust the air mix on the low end I did not know there was any adjustment to be made there. Guess I was lucky, it ran flawlessly and started on the second flip every time. The reason it is sitting in my tool box now is lack of power, I was much happier with the 46 pro. Will use the GP42 again someday when I build a lighter plane or give it to the club to use in a public trainer.
Reply to
Charlie H.

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