I love this stuff
To be doing 70@3000 requires 3.55s and tires 27.8 tall.I skimmed some of the posts and may have missed your saying this; no matter, math is math, and it doesn't work out with 3.23 or 3.7s so I'm good with 3.55s.
Ok so if you install the od-box (that's what I call it), with no other changes, the cruise Rs come down to .73x3000=2190rpm/2660@85
And that would be fine for a 360 with a cam of about 220/225, or less.That size of cam is out of reversion just about there,(maybe as low as 2000) and all the air in the intake is finally going in the same and right direction, so you can tune the cruise-circuit lean, for mpgs.By the time you get to a 250*cam it's hopeless at 2200. Even my 367/230*cam, which cruises at 2250, get's terrible fuel mileage.
And a 360 with a 220/225 cam makes gobs and gobs of torque to pull those splits. It won't be a racecar, but with your wagon, Ima thinking that's OK.
Bottom line is if you have a low-rpm 360 like with a 220* or less cam, it will pull that od-Box just fine. If you have a high-rpm 360 like a 250* cam, I wouldn't go back there. Between 225 and 245, it's kindof whatever you're willing to put up with.
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Ok so, here's a brief description of my thoughts, experiences and opinions.
Lets look at the ratios;
your current box which hopefully is the 2.66-1.91-1.39-1.00 which has splits of .72-.73-.72 and that's pretty sweet. Whatever RPM you shift at, the R's will fall to those %s in the following gear. Example: shifting at 5500,the Rs will drop to 3990ish. So to satisfy that,your engine needs a powerband of 1512rpm.
And the odBox, is 3.09-1.67-1.00-.73 with splits of .54-.60-.73. Again shifting at 5500, the Rs will drop to 2970 and 3300, making a powerband requirement of 2530/2200.This,by itself is not a big deal in a lightweight car with a torquey 360, unless you want hi-performance.
So let's install them, and look at the overall gearing, with those 3.55s.
Currently..... 9.44-6.78-4.93-3.55
odBox........ 10.97-5.93-3.55-2.59
Notice third gear. This is a loss of 28%TM (torque multiplication). The only way to get it back is with 28% more rear gear..........Which totally relegates first gear to being useless; (4.93x3.09=15.23).
Ok but. line 'em up like this;
...........9.44-6.78-4.93-3.55
...10.97............5.93....3.55-2.59
Now you can see how it really compares. The odBox gets you a deep low, then a gear between Second and Third, plus the delicate OD gear that even a 3184bbl blows up, if you're not careful. Ok so look at that. Imagine your 360 plowing thru those gears with the new TM. If you get the idea that I'm not a fan of that box and a high revver, you would be right. I tried it with several different rears and was never happy.For my engine, Second gear was just too far away. So what to do.
Well, I got me a 3.09Low Commando trans (C-Box) and converted it to a slip yoke, and changed the rear gear. It could look like this in your car; with no od.
std box 2.66x3.55 9.44-6.78-4.93-3.55 the current combo
C-Box 3.09x3.23s 9.98-6.20-4.49-3.23 % difference +5.7- 8.6,-8.9-9.0 and 70=2730
C-Box 3.09x2.94s 9.08-5.64-4.07-2.94 % from current-3.1-16.8-17.4-17.2; 70=2480
The splits are still all the same, so the only places I actually noticed the wonkyness was on the slightly different 1-2 shift, and it stays in each gear to a slightly higher roadspeed, which translates to slightly lower performance, but not near as bad as the od box.
I tried the 2.66 box and 2.94s but I found the 7.71 starter too lame for a 292/508cam, and I didn't much like it with a 230* cam either. That's when I bought the GVOD and started splitting those wide gears, some right up the middle; 3.09-2.41-1.67-1.30-1.00-.78/.73-.54
And I gotta warn you; I blew three of those boxes up. My winter 3184bbl shredded one od gear. and my regular 360 also shredded one od gear. But it also shredded all the teeth of the input gear, of a third box, leaving me with a nice clutch line-up tool. So if you need parts,lol............. I tell ya it ain't easy trying to remember to ease it into that od-Fourth!
