if you can get in good with a dirt car racer, modified, late model, in your area. some of them will have 4 corner scales at thier shop or garage made for car weight. the bathroom scales will only work good on a smaller scale. i used them on my go kart when i raced it. ive heard people say they used bath scales stacked like 4 high on each corner or something crazy like that. but it has to be a true level peice of ground to get fair results.

in my anglia i set it up at 10% back according to the rules for a certain class. that is 10% of the cars total wheelbase, the #1 spark plug hole can be set back in the chassis, from the front wheel spindle. mine is 93 inch wheelbase, and i set the engine back 9 3/8 inches from spindle.