(Over) Drive Time?


I have (finally) gotten my ’69 Charger R/T 440 to the point of routinely driving it (that’s what these cars are for, driving them) and am, of course, not satisfied: even with 3.23 rear gears—it’s turning 2600‑2700 RPM cruising on the Interstate. I’ve seen references in your tech answers online to building a stout 518 on the cheap by swapping the parts in the built 727 in the car now into the forward section of the 518, which would have the benefit of limiting upgrade/rebuild to the overdrive section of the 518. I’ve not had success researching in catalogs exactly which 727 parts would not cross over, requiring me to re‑use/upgrade the 518 parts. 518 output shaft, I’d imagine; valve body would obviously have to be the one from the 518; 518 input shaft if I want the lockup torque converter, but what else? I can’t seem to find an article describing this swap/rebuild in the tech index; if there is one, just let me know and I’ll snag that issue. Not part of the question but a complement: I’ve read in your mag the path of wisdom is to get the timing curve right first and then mess with the carb; are you ever right! Finally fixed the “all‑in‑by‑1500, advanced at idle” timing curve in the Direct Connection electronic ignition conversion distributor to a street‑suitable starts at 1200, all in by 2500 curve and what a difference.

Want a big-block automatic overdrive tranny? Your choices are: (A) A518A with block adapter,
kinda hokey, (B) Keisler’s bolt-in 4L60 (shown), good up to ~500 HP, (C) TCI’s 6X 6-speed (100%
bulletproof, tough install), (D) Hang-on (cantilevered) OD (GV), strange U-joint angles.

I never wrote that, because it can’t be done. Sorry. Using a 518 directly on a big-block
requires a lot of case hacking, welding, and precision machining. Somebody needs
to come out with an A‑518‑B case. In the meantime, there are adapters (lousy
way to go), Keisler’s 4‑speed AT, and TCI’s beefy 6 speed.
The other fix, simple: Taller gears. The car will pull 2.76 or 2.94:1 like a dream.

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