i have a knock in the top of the engine and only knocks on accelleration

If you think it is an ignition/ spark knock, Try a better grade of gas with higher octane, Be sure the fuel filter is clean and you have fuel getting to the injectors, also you could have plugged or poor fuel spray from injectors. I would look at spark plugs and sell if any of them are very lean / white / hot in appearance. Is the ignition timing right?? I would have a mechanic listen to it as you can do engine damage with bad injectors.. Carl H