AtTheLake

Going to swap out the 7" for an 8" rear. I can pick any gear and was leaning towards a 3.25 or 3.00 but I am not 100%on either of those. Ohh I guess it might help to know it is going in a '67 289-4v with a C4.We will mostly drive it around town butI'm sure it will hit the interstate here and there - no track time in the forseeable future though. What would you suggest for a Sunday driver? It would help me to to knowwhat kind of RPMs a 3.25 turn at 70MPH with my setup?


Also swapping out the drums up front. Are these Ebaykits any good? I found 3 different kits listed andare any one better than the others?

http://cgi.ebay.com/ebaymotors/ws/eB...08775&rd=1


THANKS!

TexasAxMan

That's the brake kit I bought. It's very complete and the vendor (Dennis) is real easy to deal with. High quality stuff.

As for the gears, I think most recommend 3.55. Someone else will chime in soon though.

109jb

Why not a 9" rear??

You can figure the engine rpm using this:

RPM =336.13*SP* RR / TD / OD

Where SP is speed in MPH, RR is the rear end ratio (ie:3.25), TD is the tire diameter in inches, and OD is the transmissions overdrive ratio (1.0 for a non-overdrive)

3.25 would put you around 2700 rpm at 65 mph, 3.00 would be about 2500 rpm with a typical tire of about 26 inches diameter.

Oxnard Montalvo

How much is a gallon of premium these days?

I have a 289-4v, a 3.00 rear with trac loc and a toploader, it may not be the fastest off the line, but I get decent mileage @ 65 mph (17-19mpg) on the interstate and can cruise @ 80-85mph (3300rpm) with no strain. (My mileage does drop off significantly @ 85mph.)

This rear works for me because of the price of petrol and the fact that I like to drive my car.

AtTheLake

109jb - great formula, thanks! Got meleaning toward a 3.25 - sort of a compromise between efficiency andumphhhh.

Ok this is where my ignorance shows, but was a toploader??? And should I be looking at 9" rears? I really didn't give it much thought due to expense and thinkingthat my enginereally isn't in the big leagues in terms of gear breaking torque.

109jb

If yourgoing to stick with your 289the 8" is fine, but I would think down the road what you want to do though so you aren't repeating the process. You said "no track time in the forseeable future" which I took to mean that it's possible some day. If you don't think you will be doing much to the engine then 8" would be OK, but if you ever see a stroker or significant horsepower gains then you may want to think about a 9" now. That's all I meant.

sixt5

toploader = 4 speed stick shift

i have a 65 and swapping a 4 speed in a few weeks. gonna lean toward a 3.25/3.55 with a traction lock. its not my DD and not really worried about gas mileage.