Craigslist 4 Speed - Something doesn't jive?
aj/forms , what do you thing it got 247 or 266 first or did the /6 carry over the 309 ?
You lost me!
The 2.47 was a one year deal IIRC, possibly 2, and it came only in the small-block T/As and Cudas. in 70/71 I think
The 3.09/ direct only came in the early 273 HO cars, AFAIK
Everything else got the 2.66 low.
Unless it was an overdrive; all of those come with a 3.09low.
The 2.47 is a great street set-up.But to get off the line,you have to run some pretty mean rear gears, like 4.30 or more. With 4.30s the starter gear is just
10.62. And honestly the splits are only 2% to $ 4% closer
which is about 200/300 rpm. So that starter gear sacrifice to a streeter is unacceptable.
I really like my 3.09/direct box. I get a starter gear of 10.97 with just 3.55s, and
9.98 with 3.23s.Either works for me..
The 2.66 likes 3.91s to get
10.40.
The 10 to 11 range is good for any SBM with modest low-rpm torque, like a 360 with a 230* cam, a 340 with a 220* cam or a 318 with a 210* cam . Of course crappy compression wants closer to the high side and strong compression can dip a little under. By 9/1 things are getting slow. 8.5/1 is an unhappy place.8/1 is downright ugly. At the other end 12/1 is dragrace with a stout engine 13/1 for a small engine and 14 is ridiculously hi, suitable only for low-powered engines. I once tried 15/1 with my 367 which was a total failure, but I had to know.
You can figure out the low-gear ratio from the speed,rpm,and tire roll-out of an installed unit. Or if on the bench, by the number of turns of the input shaft compared to exactly one turn of the output shaft. In all cases extreme accuracy is required to see the difference between the 2.66 and the 2.47.
Of course a tooth count will be the most accurate.
