Does it do it if you leave the car in high gear and run it up light throttle, then nail it to 6K? If you are looking for a budget module, find a Standard Ignition LX-101. It wont pull out timing like the orange box and the quality is more consistant. I've got 3 potential spots.. The carb.. is it new? Crap in it somehere? The ignition box... Is it grounded well? Is teh egnine grounded well? The valve springs... I think you should have enough with the GM 3100 springs but I can't recall what the presures are. Which is why I ask if it will ever rev beyond 6, or just in first. If it never would... I'd pull a spring and test it.