ok,for my 72 f100 with a 3o2 and c4 wut gear set is better for highway running 3.73 or 3.25 ?

 

Using the 3.25 gears would result in lower engine RPM at cruising speed then the 3.73's. As far as which is better, it comes down to which you prefer, the 3.73's would give you a little better off the line acceleration, the 3.25's should be a bit better on fuel mileage.

 

ok,kool,thank u very much ur help

 

You also have to take into account your tires overall diameter. If you have to tall of a tire, the 3.25 would hurt your acceleration. Something to think about.

 

hell,im only got 15 inchers so,that shouldnt worry me

 

The 3.25 will kill your fuel mileage.
The 302 is a short stroke engine, at 3.00 inches, which develops power at higher RPMs than a long stroke engine. With a 3.25 ratio, you will not be turning enough RPMs to be in the 302's power band, which means you have to give it more throttle. Unless you are doing 85 MPH or higher. Your RPMs need to be in the 2500 - 3500 range (or higher, if you have a "performance" engine) to be of best power value - and the 3.25 will not let you reach that at legal speeds.
Even the later trucks, with fuel injected 302s (5.0 liters) have 3.50 (or close) rear end gear set in them.
With a 351, you can safely go to 3.50, possibly to 3.25. With a 400 or higher, you can easily go to 3.00, and possibly to 2.75. With a 300 six, you can go to 3.25 just fine, because it is a high torque long stroke engine. Both the Ford 300 in-line six and the 460 have nearly 4 inch strokes, making them more suitable for power at the 1800 - 2200 RPM range.
I had a 352 V-8, with a 3.50 rear, and it did 15-18 MPG at 75 MPH. But when I put a 2.75 in it, it was so dogged out that I couldn't start off from a stop sign unless I feathered the clutch. It had a 3.50 inch stoke.
Now I have a 460 in it, and the 3.50 is too low. I will put a 2.75 into it, and it should do just fine - but it is a longer stroked engine designed for low RPM torque, and has way more power than your 302 has.

 

im mainly looking for for freeway,so and im a fast driver as it is,lol,so thats fine

 

What diameter tire are you running on the rear?? according to my calculator, with a 3.25 gear ratio and a 28" dia. tire, at 75 mph you will be turning 2,925 RPM. With a 30" diameter tire and a 3.25 ratio you will be doing 2735 RPM at 75 mph.

 

hell,i know im going with p235/r15 tires

 

probably about a 27.5 to 28,5 diameter tire, should work good......

 

thank u dave,ur the first person to say something good about my swap

 

Your welcome. I can't take the credit, just punched your numbers into the software somebody made!!! I do like using it, takes the guesswork out of a lot of combinations.

 

wuts that calculater at,i would like to use that,kool stuff

 

Mine came with a software package that I bought from Summit. I believe it cost about $80 and also has the virtual engine dyno. I've had it for a year or so and it seems to be quite accurate. The engine dyno part of it allows you to check out a bunch of different engine component combinations and beats the heck out of spending a ton of money on parts then wonder if something else is better. Check out any of the online parts stores, they all offer different software packages. "Real dyno" time around here goes at about $200 per hour......