Quote:
Originally Posted by MikeB
Valid point about the 700r4 being a simpler solution. I guess its biggest issue is initial TV cable adjustment. And it goes beyond making sure there is zero slack at idle! If a non-OEM carburetor doesn't have the proper geometry-corrected throttle lever, there will be either slop at idle, or the carb won't go to WOT. And even with the lever, you must make sure the valve travels to its stop at WOT, or line pressure will be too low. With specific Q-jets and throttle bodies it shouldn't be a problem, because they were designed to work with the 700R4 and 2004R.
Not only that, but once the TV cable is correctly adjusted, any carburetor idle speed adjustment that you may have to do periodically (like winter/summer) requires a re-adjustment of the TV cable. But again, with EFI, it shouldn't be an issue.
I doubt that most transmissions shops understand the above unless they are familiar with non-factory type installations
On another note, how do you feel about the ratio spread between 1st and 4th gear and then converter lock-up? On a friend's car, a 37 Chevy with a 350, 1st gear is so low that the 1-2 shift happens after a couple car lengths. 4th gear seems too tall, especially when the converter locks-up. In fact, he keeps the shifter in 3rd gear until he gets on the highway, and controls lock-up with a dash-mounted switch. But again, all that may be due to not having a vacuum switch to control the trans, and whatever else a stock installation has. His car has a 3.36 axle and 29" tires.
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Most vehicles that are 'not stock' prob don't need OD until they're actually on the highway. That '37 Chevy you mentioned is only @ 1750/45mph & 1950/50mph. He has no need for 4th gear in town.
Heck, the math says that combo is only moving along @ a tick over 2700 @ 70mph in 3rd so that 700r4 puts him kind-of under the target zone of a traditional warmed-up sbc @ just under 2100rpm @ 75mph unless it's a low rpm/torque built motor. For C10's, I'd want minimum 2200rpm & be good w/24-2500 @ ~75mph.
As far as 700r4 vs. a 3spd auto/GV OD for someone that doesn't personally have experience with/or 'have a 'guy' for transmission builds? I'd do the GV for fewer headaches & better rpm splits between gears.
You're likely to spend the same amount (well built 700r4 vs GV) on initial purchase unless you build one yourself so that's a wash. The finicky TV cable adjustment is always a concern when poking around under the hood (not a big deal on the average Joe/Janes all-stock/EFI'd mass produced set-up). Not that the GV doesn't have it's drawbacks though (don't put it in reverse when it's engaged or it will be done). The GV gets the nod for strength when OD is engaged.