i got a 350 in my elky when it gets over 200 it starts to lose power and pop when i floor it or drive fast. i got a fan shroud and new thermostat now it runs at 180 and still pops when its warm out? what can it be

What do you mean by "pops"? Since that's not really a technical description, it'll be hard for us to help you. Please explain what you mean by "pops" and give us a bit more detail. Is it backfiring through the carburetor? Or, does it sound more like detonation?

Sounds like a lobe on the cam is rounded if its popping back through the carb.To check if that is it, you will have to pull the valve covers and watch the valves while spinning the motor over and see if one valve is not moving as much as the others..................Dan

it does sound like it might be poping from the carb, it happens when im sitting inside driving it just loses power and yea backfires... it only does it when its hot when its warming up or under 180 i can floor it all i want and it will be just fine.

Could be a problem with your choke not working properly if it only happens when warm. I also had problems with a warped gasket in my carburetor causing similar effects.

Change your plugs first, then wires. Even fresh plugs sometimes do that on SBC's. Also I never had any luck with Champion plugs in a 350. If thats what you're running, try another brand, NGK or something.