Hi I have aquired a few older glow engines any products out there that will disolve varnish Or tips on how to remove varnish without destroying engine

Try Dawn Power Disolver.

Good reading here:

http://www.airfieldmodels.com/inform...aintenance.htm

The caustic grease removal substances will ruin your engine if left on the aluminum long term.

Notice the Cascade should only be on the engine for a short time in the instructions

The dawn can stay on about 45 min

You can also get a potpourri pot and put 50/50 antifreeze in it and you can soak the engine in the solution for a week. Do not boil

Using grease removal stuff BE SURE to rinse it good . I like the Dawn but have to really rinse it good. ENJOY !!! RED

All you need is a spray can of Gummout...(automotive carb cleaner )
Obviously, you should use it outdoors...and wear eye protection.