http://www.chevelles.com/showroom/FO_FDYFO/steeringbox02.jpg
here is how i checked the ratios. i took an aluminum plate and taped a piece of paper with degree marks on it. bend a wire indicator to something stationary and bend it to 0 degrees. then i bolted a wire to the steering coupler. rotate the steering coupler a perfect revolution or 2 or even 3 if you can. the more turns the high accuracy your measurement will be. then look and count the degrees the pitman armshaft has rotated. devide that number by the number of turns you made the coupler turn and write that number down. divide 360 by that number and that is your steering ratio. for example, i turned the coupler 2 times (720 degrees) the pitman arm (plate) moved 56 3/4 degrees. devide that by 2 turns = 28.35. 360/28.35= 12.7 that is the ratio.
a 14:1 box will move 25.71 degrees for each turn. i have tried several boxes. i bought a 88 monte ss box and checked it for 12.7:1 and it is. the stock 70 chevelle box was 14:1. ;)

Nice setup! I like it! graemlins/thumbsup.gif

Good looking setup! There is only one other thing that I would suggest that you take into account.

Some Saginaw gears are variable ratio. For example 16:1 on center and 12.4:1 near full lock. If you just take the average from corner to corner on a variable ratio gear, you will end up with some number around 14:1. So a variable ratio gear will not feel quick and fast right on center.

So what you need to do is just take a quick check 45 degrees either side of center as well as another check near full lock to determine if the ratios are the same (constant ratio)or are they different (variable ratio)gear.

You most likely want the constant ratio 12.4:1 or the 14:1 gears. All of the variable ratio gears were either 15:1 or 16:1 on center (which you probably don't want).

Hope this helps,
Jim

Above fair!!

I was in the garage about 2 hours ago thinking about how to do this exact same thing. (Got a box off an 84 Z28 but I'm not sure what the ratio is.) Now I don’t have to figure out the math myself. Bonus.

If you made your plate a little smaller you should be able to take it with you to the yard and check before you plop down your hard-earned cash.

Thanks.

thats true but a smaller plate means less acuracy.