Miloh,

The Thunder Tiger PRO 46 is a standard of the model airplane engine industry. It stands right up there with the best 46 Schnurle ported ABC type ball bearing engines. I take it that you have an oportunity to obtain a used one? Just make sure it feels smooth when you turn it and that it has plenty of compression.

You will enjoy the TT PRO 46 engine. It's in a bigger league than your Tower GP 40 type engine. A new Thunder Tiger PRO 46 has a good price also.

If you still have trouble with your Tower 40, See if the LA 40 carb will fit and try it in your Tower?

Keep in mind that your Tower 40 is no longer being made and that parts may be hard to come by? The newer Thunder Tiger GP42 (though a good engine) is made a lot different. I doubt if anything will interchange between the two?

Enjoy,

Jim