I have two ground wires from my engine block to the frame rail. One on each side. Then I have a 2ga. ground wire from the battery to the rear frame rail. If it isn't grounded well enough you will find out. Just try to start the car at night w/o any lights on. Any where you have a really close metal/metal point you could see sparks. Don't ask me how I know. My brother pointed this out to me one evening when he was visiting. I was getting an arc between my one header pipe and the inner fender.
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Not good. Put another heavier ground on the block and took care of that. Starter spins much faster now also.
Also go to NAPA and get a heavy duty fuse to put in your positive wire. I have a 300A fuse in mine. Yes it will still do some welding if the wire gets cut, but not as long as it would if it were not fused.
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