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-   -   700r4 vs 4L60E swap for powerglide (https://www.impalas.net/forums/2-general-tech/37740-700r4-vs-4l60e-swap-powerglide.html)

NZPhil 04-15-2019 04:16 AM

700r4 vs 4L60E swap for powerglide
 
I’m wanting to upgrade my powerglide in my 61 to a 4 speed auto for cruising. I appreciate I could look at the 200r4 or the 700r4, but is it worth looking at the 4L60E now there is seems to be good computer option? Only looking at 350hp.
Whats easier and cost effective?

Big Dave 04-15-2019 10:28 AM

You gain nothing with adding the transmission controller computer over the fulliy manual 700R4 transmission. The 700R4 relies upon RPM and line pressure to activate the electrically operated lock-up clutch in the absence of an OBD II computer. If you are thinking of going further and submitting to the dark side by buying into the EFI myth, then it might be justified.

Just want to point out that a carb makes more power, allows a more radical cam than EFI does at one sixth the expense. A carb won't win a mileage contest, but few buy high horse V8 motors to get better mileage. The reason the factory went to EFI was to pass emission tests.

Big Dave

NZPhil 04-15-2019 04:49 PM

Thanks Dave, no plans to go EFI, quite happy with the carb just need some more gears for highway cruising.

NFURE8 04-16-2019 09:06 PM

What sort of Modifications do you need to do to exchange a powerglide with a 700r4 or even a TH350?

im guessing its not a simple pull one out and put the other in job

Big Dave 04-16-2019 11:30 PM

Shorten drive shaft because the 700R4 is longer. Modify or replace with an aftermarket transmission cross-member because the mount is further back.Add a TV cable because it uses a throttle position cable instead of engine vacuum to shift (and it has to be correctly adjusted or the tranny will self destruct. Modify the shifter linkage (aftermarket has the parts) because you now have four forward gears instead of only two. Finally you need to rig up a torque converter lock-up switch to go racing (you need it off to race), or modify the tranny to do it automatically all of the time (engages above 45 all the time).

Metric instead of SAE fasteners (in the tranny and the torque converter), and tubing uses O-rings instead of compression fittings.

Big Dave

Deadwolf 04-17-2019 11:25 AM

If memory serves me right the 200R4 requires no change to the driveshaft. All the other mods for the 700R4 stand. The 200R4 isn't as strong as the 700R4, but for a mild 350 HP engine it should do just fine and is a cheaper transmission overall making the conversion cheaper.

Big Dave 04-17-2019 03:43 PM

Quote:

Originally Posted by Deadwolf (Post 223674)
If memory serves me right the 200R4 requires no change to the driveshaft. All the other mods for the 700R4 stand. The 200R4 isn't as strong as the 700R4, but for a mild 350 HP engine it should do just fine and is a cheaper transmission overall making the conversion cheaper.

A used 200R4 isn't as strong as a 700R4 unless it was out of a V8 Chevy police cruiser or a Turbo Charged Buick V6. The standard V6 tranny (just like a Chevy with an in line six PowerGlide) isn't teribly strong. But if you replace all of the internals with aftermarket parts a 200R4 will handle a blown BBC (1,200 hp).

Additionally the 200R4 uses the same cross-member as the TH400 (which in early Chevys had to have mounting tabs welded to the frame).

Big Dave


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