Future project planning (Advice Needed)

[Fancy]

So I need a little help doing some future planning for my truck. I currently have a 1990 full size blazer with a 350/700r4/241. It has about a 4-6” lift with 60/14ff (4.56)and 39.5” TSL’s. It is not my daily but it sees a lot of road time and needs to be able to drive to and from wheeling comfortably. My wheeling is moderate most of the time with the occasional adventure that is hard on it.

The problem is my drive train is slowly going as the engine is nearing 200000 miles and my transmission acts up sometimes. So when the things begin to go I want to have a plan for a swap. I know little to nothing about this as far as what would be a good combo for a great all around rig that is street oriented.

Below is my current thoughts on each main component but, any information, opinions, or even do’s and don’ts are welcome. Pictures are always a plus

Transfer Case:
As far as transfer cases I was thinking about putting in a doubler. I like the atlases but I was told they are not for full size rigs and they are way too damn expensive. Lol

Transmission:
As far as transmission I kind of want to keep it automatic and being that it sees alot of street time I was told a well build 700r4 would probably be my best option but again I still don’t know much about transmission either.

Engine:
The engine is where I am the most clueless. I want some POWER but I don’t want to destroy my gas mileage and practicality. I have been playing with the idea of just a new 350 or toying around with the idea of a 383 or even 454??? I really like the idea of going diesel like 6.5 or even going extreme and swapping in a newer diesel.

Overall:
As I am not made of money and it will be best if I can do this in stages or steps. I was thinking of swapping my 241 for a 205. And later adding the 203/doubler kit. I also wanted to add the driveline ebrake to that as well. As for as the transmission I was thinking leave the 700r4 and either rebuild or by a new one when the time comes. Then that leaves the engine where I am still undecided.

But please let me know what you think?

 

[boz42]

Transfer Case:
As far as transfer cases I was thinking about putting in a doubler. I like the atlases but I was told they are not for full size rigs and they are way too damn expensive. Lol

An atlas will hold up in a fullsize. Personnally I would chose the Doubler. I usually can find those parts easily locally so it is cheaper. If you had to buy the t-cases from a reman place it would prolly be as expensive as the atlas

Transmission:
As far as transmission I kind of want to keep it automatic and being that it sees alot of street time I was told a well build 700r4 would probably be my best option but again I still don’t know much about transmission either.

A properly built 700 would be fine. Just make sure you run plenty of trans cooler & a good convertor from a supplier that understands what you are doing witht the rig. I have seen high end convertor builders fail at building offroad convertors. Another thing to consider in assisting the 700 to live would be deeper gears.

Engine:
The engine is where I am the most clueless. I want some POWER but I don’t want to destroy my gas mileage and practicality. I have been playing with the idea of just a new 350 or toying around with the idea of a 383 or even 454??? I really like the idea of going diesel like 6.5 or even going extreme and swapping in a newer diesel.

This one is just a personnal preference. Just decide what engine you are going to run before you sink a load of cash into your trans. If you go diesel you would need a different convertor at the least.

Overall:
As I am not made of money and it will be best if I can do this in stages or steps. I was thinking of swapping my 241 for a 205. And later adding the 203/doubler kit. I also wanted to add the driveline ebrake to that as well. As for as the transmission I was thinking leave the 700r4 and either rebuild or by a new one when the time comes. Then that leaves the engine where I am still undecided.

But please let me know what you think?

In my opinion you gotta pick your engine first. That will determine which transmission or in which manner the trans needs to be built.

I would not bother swapping to a 205 unless the 241 came apart. A doubler needs a 32 spline input 205. Your 700 needs a 27 spline input 205. These 205's have different input bearing sizes, meaning that the 205 that goes behind your 700r4 would need to be machined for a larger bearing & then have the input shafts swapped.

 

[Fancy]

First of all thanks for the reply Boz42.

I couldn't agree more about deciding on an engine first that is why i am posting this it's the most important piece and i am the most undecided on it. I am really thinking deisel with a 700r4 0r i hear the 4L80 auto would be a better choice maybe. But alot of my buddies tell me desiel is bad for wheeling but they can't tell me why????

As far as the 205 i was told to get one off of a th400 (i think it was) with a 32 female spline input and then buy the shaft conversion from ORD for my 700r4 or swap in a 4L80 and that would work. I still need to do a little homework on the subject but it is the 203 that connects to the tranny right and the 205 to the 203?

anyway it is the engine and tranny setup that i need the most help with i really was hopping for opinions and advice or to her what other people are running who use their trucks in the same way

Thanks again

 

[boz42]

Diesels have a few disadvantages offroad in my opinion. They are a lot heavier than a gas burner. Extra weight kills you on the trail. Especailly when located over the front axle. Keep in mind I am just saying in comparision to a gas burner. It also depends on the terrain. In the deep south were I am you need a lot of tire speed. A stock diesel just doesn't pour it on like I would want it to. Now a heavily modded one does but then that brings up a whole different can of worms for trail use.

Yes a 4l80 is a stronger trans, but unless you are gonna try to make stupid power the 700 would be fine. Also for the kind of use you described I would say the 700 would be fine.

I have never seen an input conversion shaft that lets you adapt a T-400 (32 spline) input 205 to a 27 spline for a 700r4. I have never looked though.

Really you need to decide how much power you think is enough. Let that decide which engine you want. That number will dictate what you need as far as fuel requirements so that would tell if you could stay with a stock style efi.

Also I see you are in CA. I thought all you fellows had to do inspection. How do you plan to get around that?

The best advice I can give anyone thinking about going down this raod is this:

No matter what you do try to never let your rig be un-streetable for more than a month at a time. If you do it becomes a pain & takes a lot of the fun out of it.

 

[Fancy]

thanks for the helpful advice!!!

I am basically thinking this as of now. After doing a little homework and seeing what you have to say i feel my plan is to mate my current setup (350/700) with a 203/205 doubler (assuming that what i read about converting the shaft was correct) I would drop the tranny and convert the shaft/rebuild the tranny and mate it to the 203/205 setup. But first decide what kind of engine to put in it.

I've pretty much narrowed my options to 350,383,454, or 6.5 all of which if i am correct can mate with my 700 with variation of course between gears and diesel. i guess my question is i like the idea of a 454 but what kind of gas mileage or fuel consumption is that compared to a worn out old 350 and is that to much power for a 700r4. Kind of afraid it is to much and i have never been in or around one to ask about it.

as for CA law well ya i'm aware of the bull**** that it is but i can work through it. And your last comment is right on the money. Been have way through a project when my money dried up and their my truck sat

 

[72blazerguy]

After doing a little homework and seeing what you have to say i feel my plan is to mate my current setup (350/700) with a 203/205 doubler (assuming that what i read about converting the shaft was correct) I would drop the tranny and convert the shaft/rebuild the tranny and mate it to the 203/205 setup.

Do you really want a doubler? Don't get me wrong, I have one and love it, but I had a TH350/NP205 which is about the crappiest low gear set you can get. The costs add up quick. The NP 241 is a decent tcase and if you do a SYE kit, should be fine for the application that you described. Your current low range is 2.7:1 and you will be running 4:1 with the doubler, but it comes with some problems. New driveshafts (probably need rear CV - $$), cross member fabrication, possible exhaust relocation, new shifter, possible speedometer problem, ect....The doubler kit is great, but is not an overnight affair.

I've pretty much narrowed my options to 350,383,454, or 6.5 all of which if i am correct can mate with my 700 with variation of course between gears and diesel. i guess my question is i like the idea of a 454 but what kind of gas mileage or fuel consumption is that compared to a worn out old 350 and is that to much power for a 700r4. Kind of afraid it is to much and i have never been in or around one to ask about it.

Have you considered a GM crate 350? Cheapest option I bet and you can get decent HP out of them. It would be direct bolt in and not require upgrades to your fuel injection.

Been have way through a project when my money dried up and their my truck sat

Switching motors and tcases can get expensive in a hurry. Is there a reason you want to swap all of the stock parts out?

 

[63chevyll]

If it were me....(you asked)

I would buy a crate 383 long block (or build one if you have the resources), if you want bolt In easy power.
Have the 700 built buns reputable trans shop with a good converter and larger trans cooler. Leave the 241 and be done with it. Use it an abuse it,

If the. 241 give up later on deal with it then.
Sounds like you have decent rig and a stock to mild engine will do wonders compared to a slipping trans and worn engine.

 

[Fancy]

Thanks for all your reply's it dose actually help me make up my mind slowly.

72blazerguy, the only reasons i wanted the doubler was to have more precise control ie. front and rear seperation and to loose the slip yolk. I am currently having problems with my drive trian which is why i want to start planning and be ready. I have explored the crate option and really like the idea but i'm afriad to spend the money and then want more power but it is definatly near the top of my chices.My dad has a 350 in his suburban and it isn't bad but i think i would like a little more power than that. (although not sure how old his is either.) i just want to be able to get on the gas when i want/need to and have it move (unlike it dose now ....)


i can probably piece and build the doubler cheap it's like was stated the drive line and crap that gets expensive.

I just wish i had something to compare it to, but everyone around where i live drives jeeps or yotas.