I'm in the process of building a ratrod that will have a 250 power plant, with a power glide. The tires on the back will be 17 to 20 inches. What ratio for my differential should I have?

Usually I read that a 3.31 to a 3.55 is a good ratio for the street,but I guess it depends on what you're looking for in seat of the pants performance.

Do you mean 17"-20" wheels? What tire diameter. What vehicle? What will you use it for, mostly? By the way I personally hate the term "RATROD." People call my pick-up that and it hurts my feelers!

Oh yes, What engine mods, if any? Sorry!

This brings up a minor question I've been wondering about for a little while. What exactly is a "rat rod" and when did the term become part of the aftermarket performance terminology?

Rat rod used to be a put down (that your car was a pile of junk) now it is a style that basicly means old school, no fancy paint or upholstery, little or no chrome ect. They are cars that are more like we built in the 40s,50s, and early 60s. Most of our money was spent to run faster and there was little left for making it pretty. Pre billet and show chrome.

Thanks, Bill. Guess I'm a rat rodder at heart, then. I tend to favor what they called "sleepers" in the old days. Basically, a car that looks fairly normal but goes like stink when you push on the go pedal. Trailer queens don't do it for me, I'll take go over show any day.

I love traditional hot rods, basic, low buck, home built performers. "If it don't go chrome it!" But I'm not fond of the trend of going out of your way to build a dangerously cobbled piece of ........ I really hate it when my best efforts are grouped with piles of .... Oh well better there than the money pits at the other end of the spectrum! It's a good thing there is so much room in this car thing for us all. By the way William lets find you some rear gears! What's the car you're planning?

Rat Rod = deliberately crude. Often with mismatched parts and no flow or continuity.

In answer to the question, I'd run a rear end that matched the engine and trans. Pr Probably a 3.08 to 3.55 Gear ratio.

I run a Nova rear end from somewhere in the early 70's in my truck behind the 250 and 3 speed stick and it gets along fine.
You could also run an 8 inch out of one of the 70's mid sized Fords like a Grenada or a Monarch. I'd look for one out of a Leaf spring car so I didn't have to cut all the brackets off a coil spring rear end. Although Years ago I had a 61 Chev passenger rear end in the 48, it took about 3 hours of cutting and grinding to get the brackets off an get it presentable.

In 1941 my father and some of his friends took a well-rusted 1935 Ford coupe, rebuilt the front end, replaced the mechanical brakes with hydraulic brakes, and installed a brand-new 1941 Mercury engine ("crate motor"). To top it off, they plumbed a Sears Roebuck "top oiler" into the exhaust manifold, so that the thing laid down a thin cloud of blue smoke, and hammered a few more dents into the body to further the illusion of a "junker." According to my father, the partners made some serious money in street racing into early 1942, when rationed gasoline ended driving for pleasure. They pulled and saved the good parts, and scrapped the rest.

We might think of that '35 as a prototype of the so-called "rat rod."

God's Peace to you.

d
Inliner #1450