1986 Silverado 4x4 engine/trans swap

[little boy blue]

I just bought my first Chev pick up and it has a 400sbc/700r4 in it that is leaking from everywhere and the engine is down on power.

I ultimately want to install a built 383 with a 4L80E. I want to be able to tow my race car which is 6500# total car and trailer and up to 10000# once in a blue moon. It will be daily driven at least half the year.

I want all this to work with a Dakota Digital dash that I intend to install at the same time.

I have Warn manual hubs that I want to keep and a np205 trans.

Is there any transmission in particular that is better for this swap than others?

Do I need adapters for the speedo to function?

What size torque converter should I use

What are some other things I ought to consider?

tia.

 

[Craig 85]

Brakes would be my concern if you are towing 10000 LBS.

 

[little boy blue]

Can anybody guide me in the right direction.

 

[AuroraGirl]

You shouldnt make your truck "go" if you cant "stop"

My truck does not extend beyond my yard at speeds less than 5mph, so I have not fixed the stop perfectly. if i was going further, i would fix the brakes far before I work on the go
he gave you guidance.

Fix your brakes first.

Once you have that, you may go the route of th400 and a cooler. That would be HD. But you also may want more mpg and better RPMs generally. 700r4 with a cooler can do a decent amount, but its going to hit a limit at a certain point.
If you are into swaps... have you thought about a 4l80e?? It needs a controller and custom work but it would suit your desire.

Also, a 400 should not be factory optioned in 1985 to my recall, so are you sure you hav a 400? what makes you say that?

And if you dont mind swaps... if you do the route of 4l80e naturally one could do LS at the same time. im not actually going to suggest it but you seem more open to throwing new parts at it than most of us are. But if you want to stick old school, the dakota gauges can work with dam nnear anything i think. They have adapters and senders etc to your hearts content.

 

[CrazyArk]

The 400 means you got the crank to make a proper old school 383 at least.

Building up an engine is a must, the 700r4 is excellent for MPG, but I have heard it can be finicky under extreme loads, the 4L80 will undoubtedly need controllers to make it shift correctly, a THM400 will have some power loss due to it being a more complex version of theTH350, but it is meant to handle a harder beating. (My truck came factory with a THM400)

If the NP205 is solid and doesn't need to be rebuilt, you're golden, but it's needle bearing setup inside versus the 208's ball type roller bearing makes the 208 a much easier to rebuild beastie, you need to be insanely careful on the 205 disassembly cause those needle bearings exploded everywhere on the one disassembled on my end.

Definitely, most definitely research the heck out of brake system upgrades, stock when tight are quite responsive, that trailer weight, it's a given its gonna have brakes, but make sure the frame, suspension and drivetrain is rigid enough to handle such a load. I'd aim for a full floating rear axle just to be safe.

Won't deny it will be a heck of a challenge, but! You do this kind of work to the truck yourself, it'll make it a breeze to maintain, since you will know it inside and out.

 

[little boy blue]

You shouldnt make your truck "go" if you cant "stop"

My truck does not extend beyond my yard at speeds less than 5mph, so I have not fixed the stop perfectly. if i was going further, i would fix the brakes far before I work on the go
he gave you guidance.

Fix your brakes first.

Once you have that, you may go the route of th400 and a cooler. That would be HD. But you also may want more mpg and better RPMs generally. 700r4 with a cooler can do a decent amount, but its going to hit a limit at a certain point.
If you are into swaps... have you thought about a 4l80e?? It needs a controller and custom work but it would suit your desire.

Also, a 400 should not be factory optioned in 1985 to my recall, so are you sure you hav a 400? what makes you say that?

And if you dont mind swaps... if you do the route of 4l80e naturally one could do LS at the same time. im not actually going to suggest it but you seem more open to throwing new parts at it than most of us are. But if you want to stick old school, the dakota gauges can work with dam nnear anything i think. They have adapters and senders etc to your hearts content.

Please re-read my original post...

I didn't ask for help with brakes, it already has 4 wheel discs on a 14 bolt and stops far better than stock.

I asked about trans swaps for the most part.

And AuroraGirl, It's a 400 cubic inch small block because the dampener is unique to the engine-totally different than a 350.

 

[AuroraGirl]

Please re-read my original post...

I didn't ask for help with brakes, it already has 4 wheel discs on a 14 bolt and stops far better than stock.

I asked about trans swaps for the most part.

And AuroraGirl, It's a 400 cubic inch small block because the dampener is unique to the engine-totally different than a 350.

no im saying that a 400 wouldnt be stock in 86 so just keep that in mind, but half my post was trans suggestions
but you are looking for power and trans - build your 400 or make your 383(both good options) but trans id say if gas isnt a concern, th400 and a cooler, external. if you have money and time to fab etc you can do 4l80e.

also, look at your rear ratio. 4.10 gears would be excellent for your use

 

[Ricko1966]

On your 4l80 swap if you can find a diesel parts truck snag the transmission controller and harness, way cheaper than a good aftermarket controller, and way better than a cheap aftermarket controller.I know you don't want engine advise, but still have to throw this out there Fix/rebuild the 400 there is no replacement for displacement. IMHO a 383 is a step backwards, same stroke, less bore. And you already have the 400.

 

[AuroraGirl]

On your 4l80 swap if you can find a diesel parts truck snag the transmission controller and harness, way cheaper than a good aftermarket controller, and way better than a cheap aftermarket controller.I know you don't want engine advise, but still have to throw this out there Fix/rebuild the 400 there is no replacement for displacement. IMHO a 383 is a step backwards, same stroke, less bore. And you already have the 400.

esp for towing