Help choosing suitable stall ratio for converter
The car weighs about 3500 pounds, 185/15 tires (26.5in diameter) with rear axle ratio of 3.09:1
185s? on the back? what's up with that?
and a 3.09 rear gear?
with a 2.45 low gear?
and a 2300 stall?
in a 3500# chassis?
That means, your starter gear is gonna be
2.45 x 3.09=7.57, which, at 5 liters is gonna be pretty sluggish out of the gate. 6 is better, 7 is just fine......
With 26.5 tall tires, my math says 65=1760 rpm(see below). Even with a stock cam no SBM, with a stock-type distributor, will make any decent fuel economy at this rpm/roadspeed; because that distributor cannot deliver adequate cruise timing, under these conditions. In fact, I'd be willing to bet that it will do better at 2200.
Now throw a cam into the mix, and it will only be worse. For fuel economy, this ratio demands an aftermarket stand-alone timing computer.
Or
just gear it up to 2200 and call it done. The engine will want about 56 degrees of cruise-timing, and the factory type D cannot be modded to even deliver that, but it gets close, maybe 45/50 degrees.
For 65=2200, you'd need a rear gear of ~ 3.55s and your starter-gear is now; 3.55 x 2.45=8.70, a very significant 14.9% upgrade to performance, from 7.57..
As a sidenote, I have been cruising at 65=2240 for decades, and I find it decent.
But if yur running say 6 or more liters, with a decent amount of cylinder pressure, well, that will help pull the 3.09 x 2.45 starter gear, pretty good.
But good luck getting 6 or 7 liters to be fuel efficient at 1760 rpm.
I've done really good with 6 liters, tho, but forget camming it up much.
The lowest rpm that I have run, with my 6liter, is 65=1590. It did pretty good with just 44* of timing coming from the stock-type modified distributor. But I installed a dash-mounted dial-back timing device with a range of 15 degrees. Thus I would have been able to bring that 44* up to 59*. I don't remember anymore (that was 20 years ago) what that combo liked, other than; at 1590, that 59* would have been too much. I didn't run that combo for very long tho, perhaps one summer.
My current combo runs 65= 2240rpm@52 degrees cruise timing. It likes more, but this is all she gets.
Note-1
(65x1056x3.09x.69)/(26.5 x 3.1416) = 1758rpm