T-400 to 700r4 in '84 C20 sub,454,4.11s

[bucket]

Ive towed 4k with a 97 suburban (350 Vortec/stock 91 700r4/3.42 gear/stock tire size) in OD on FLAT land at 70-75 mph and got 15 MPG.

My current Burb gets a whopping 10 mpg at 2k rpm (54 mph) with 454/400/3.21's. With my 700 swap soon to be, Ill be revving 1670 at 70 mph. There's DEFINITELY a benefit if your not towing too heavy of a load or do alot of highway cruising.



a manual valve bodied 4l80 would be more ideal. Durability plus an OD gear, especially if you have steep rear gears.

Honestly, 4K isn't much of a load. That's in the range of what some minivans and smaller SUVs should be capable of.

I've daily driven 3 different 3/4 ton 4x4 squarebody Burbs now, all of them with 33's. Two of them have been th400 (one with 3.73, the other with 4.10) and the other is the built 700r4 with 3.73's. MPG has been the same with all of them with the exception of the 700r4 truck getting a measly 1 mpg better IF the conditions were perfect. Now to be fair, the 700r4 truck would have been much happier with 4.10 or 4.56 gears, but at that point, you're not gaining any mpg.

And I agree about the 4L80e, but my wife thinks it's her truck, so she has to be able to drive it too. The current tires are now 36's, but 4.56 axles are in the future, so a GV might be in the future. But we'll probably just crank it on down the highway.

 

[80goldenburb]

Honestly, 4K isn't much of a load. That's in the range of what some minivans and smaller SUVs should be capable of.

For a factory 700 pulling nearly 9k in total weight, ild say thats impressive. The factory max is only 2k more at 6500, so if you or anyone else went beyond that, its was only a matter of time from there till it grenades
As for MINIvans, ive never heard of any be able to tow near that much at all. Those are usually for grocery gettin' and family hauling.

I've daily driven 3 different 3/4 ton 4x4 squarebody Burbs now, all of them with 33's. Two of them have been th400 (one with 3.73, the other with 4.10) and the other is the built 700r4 with 3.73's. MPG has been the same with all of them with the exception of the 700r4 truck getting a measly 1 mpg better IF the conditions were perfect.

I see what you mean now. Gearing is too steep and your powerplant doesnt have enough torque to get the load moving from a dead stop. I had a "temporary" '85 'burb work truck with 700r4 and 3.73s. It was a dog to drive with the previous owner (idiot) who swapped a 305 in that just could not pull for the life of it. city mileage was 10 mpg, highway 14. In your case, Vortec head swap will solve that problem. 3.42s worked great with 380 lb ft torquer L31 on 28 inch tires.

Now to be fair, the 700r4 truck would have been much happier with 4.10 or 4.56 gears, .

if your tbi was packin' 400 lb ft, it would. But then with that power you could go taller to 3.42s like I had. My current burb breaks traction for a split second from a dead stop (3/4 open throtte) with 440 TQ/3.21s.

And I agree about the 4L80e, but my wife thinks it's her truck, so she has to be able to drive it too. The current tires are now 36's, but 4.56 axles are in the future, so a GV might be in the future. But we'll probably just crank it on down the highway.

Nuthin much too it, just manual column shift or you could have your tunnel drilled with a stick for manual shift. and toggle for converter lockup. i would if i had the money
GV needs better ratio and still no lockup converter so youll be running hot. watch the trans temp. dont want to end up like my current one

 

[Derick C.]

I will let everybody how well or how bad mine works when I put the 454 in the burb.

The trans has already been built, how well I have no idea, and it already has 456 gears.

 

[bucket]

For a factory 700 pulling nearly 9k in total weight, ild say thats impressive. The factory max is only 2k more at 6500, so if you or anyone else went beyond that, its was only a matter of time from there till it grenades
As for MINIvans, ive never heard of any be able to tow near that much at all. Those are usually for grocery gettin' and family hauling.


Nuthin much too it, just manual column shift or you could have your tunnel drilled with a stick for manual shift. and toggle for converter lockup. i would if i had the money
GV needs better ratio and still no lockup converter so youll be running hot. watch the trans temp. dont want to end up like my current one

My dad borrows my 2K trailer and puts it behind his Buick SUV/van thing (cant think of what it's called, the big FWD) and then usually puts at least 1K of stuff on it. That thing pulls it just fine. The original question in this thread was about a 3/4 ton truck where a 700r4 simply doesn't belong. Yeah, in a stock application with little tires and towing a light load, a beefed 700 is OK, but anything beyond that is a waste of money.



And I already got a floor shift, but the wife just likes an auto trans. And the 400 is already rebuilt and ready to go in. Already got a trans temp gauge too, otherwise that 700r4 would have been smoked years ago

 

[Derick C.]

Well I have a 454 in front of a 700r now. Have yet to hook up the trailer but so far its doing fine.

 

[74 Shortbed]

I'm putting a 468 in my truck and it will have a 700R behind it..

 

[Derick C.]

I'm putting a 468 in my truck and it will have a 700R behind it..

Awesome. Let us know how it works out with yours

 

[74 Shortbed]

Awesome. Let us know how it works out with yours

For sure, be a while though as the truck is all in pieces and I'm so frikkin busy right now I don't have time to work on it.