Detonation is like marbles rolling around in the engine. Gets worse with load and engine rpm. If it gets bad enough you can actually feel the engine power drop off. Guessing and have heard when detonation occurs, roughly 10% of power is lost. Worse case we still got a 81 Aries that needs a tranny. Sell ya cheap I can even help with the tranny if you do it when I am down in fL If not I plan on getting a tranny for it either way. At least get it moving under its own power. On the detonation, check the engine temp and ignition advance, also what fuel ur running.