383

[SeventyOne]

Hey guys been on the board for awhile now but am ready to start tearing into my truck and want to get the planning done and squared away so here are some questions.

Plans are for a frame off resto/mod...

I will be putting in a 383 with around 400-450 lb/ft and want to know if a built th350 will hold up. I would be okay swapping in a th400 (that should hold up right?) but am not sure what that swap entails or

Will also be lifting the truck 4-6", doing the shackle flip, and want to run 37" tires without trimming. This will be a street queen/cruiser.

It's a 71 Blazer.

Can post pics of its current condition if someone lets me know how

Thanks!

[Jtrux]

Congrats on getting started on the rebuild. It's alot of work but fun. The th350 wil be fine, I would run a 6 inch lift for 37's if it's a street cruiser. If flexing it at all it will rub but I doubt you'll be doing any of that. I would probably run 4.56 gears but you might be able to get away with 4.11's but I think 4.56's would be a better choice and better for your tranny too.

[VA72C10]

Originally Posted by SeventyOne

Hey guys been on the board for awhile now but am ready to start tearing into my truck and want to get the planning done and squared away so here are some questions.

Plans are for a frame off resto/mod...

I will be putting in a 383 with around 400-450 lb/ft and want to know if a built th350 will hold up. I would be okay swapping in a th400 (that should hold up right?) but am not sure what that swap entails or

Will also be lifting the truck 4-6", doing the shackle flip, and want to run 37" tires without trimming. This will be a street queen/cruiser.

It's a 71 Blazer.

Can post pics of its current condition if someone lets me know how

Thanks!

If built properly the 350 should be able to handle that 383. Posting pictures is easier if you upload the pictures to photobucket (free) (use the yellow square with the mountains and sun picture). If you use pictures off of your computer (the paperclip icon) you just have to make sure that the pictures are small enough.

[SeventyOne]

Originally Posted by Jtrux

Congrats on getting started on the rebuild. It's alot of work but fun. The th350 wil be fine, I would run a 6 inch lift for 37's if it's a street cruiser. If flexing it at all it will rub but I doubt you'll be doing any of that. I would probably run 4.56 gears but you might be able to get away with 4.11's but I think 4.56's would be a better choice and better for your tranny too.

Thanks for the advice. I have always felt a little overwhelmed in getting this project started but I just figure I will start talking this thing apart, labeling the parts...find a way to get the body off the frame, clean up the frame and start putting it back together. How hard can that be

I will try to get some pics up this weekend before I start taking it apart.

[vtblazer]

I'd really consider a 4spd auto if it were me.

[SeventyOne]

Originally Posted by vtblazer

I'd really consider a 4spd auto if it were me.

Let's hear some more about this...we talking 700r4? 4L60e?

[vtblazer]

Originally Posted by SeventyOne

Let's hear some more about this...we talking 700r4? 4L60e?

Either/or, could even go 4L80 but at some point things start to get pricey with the computer controlled trannies.

A lot depends on the gears your running, your already going to be pushing the limits of those 1/2 ton axles by running 37's, plus the inadequate breaking you'll be dealing with.

If your running 3/4 tons or ton axles and I hope you are, forget about the above blathering.

Thing is a 3spd transmission is very limited, one end of the curve is always going to be a compromise.

If you have great acceleration, you end up running high RPM's on the interstate, if you run at decent RPM's @ 65mph, it's a dog off the line & around town.

Running a 4spd tranny fixes all that, you can run a nice low axle ratio for fun times running the roads and at the same time cruise the highways with an engine RPM in the 2K range, due to the over drive.

[SeventyOne]

So the question becomes can a 700r4 stand up to the power I plan on putting in front of it? Is it a bolt in swap from a th350?

I want to gear for acceleration so I am thinking 4.56's. This will see the city 80% of the time...

As far as braking what can be done with the 1/2 ton axles/brake system? What makes the axles 3/4 ton over the 1/2 aside from being 8 lug? Aren't they still a D44 and 12bolt otherwise? Sorry I am a little inept in the axle dept.

Thanks for all your help.

[Jtrux]

For starters, yes the 700r4 can handle the power. I know that an overdrive would be cool but I personally don't think you'll be needing it if your just cruising around town, stop and go driving. If you plan on alot of highway miles, cruising to shows in different cities and such then an overdrive might be worth it but it's just one more expense you'll have to deal with. A friend of mine from the board, Critter, has stock 3.73's and 35's with a th350 and it works well for him but he's planning on going with 4.10's to help move things along from a stop. 4.56's should work well for you with 37's.

As far as the axles go, 3/4 ton axles do offer alot in the form of braking. Bigger rotors up front and bigger in the back. The rear will be a 14 bolt full floating axle if you're looking for a big, cheap axle with tons of aftermarket support. A disc brake conversion is cheap as well. You can upgrade the front 6 lug dana 44 but there's not a whole lot you can do for the stock 12 bolt cheap.

[vtblazer]

Jtrux is correct, you certainly don't need an over drive tranny and by adding one it only adds to the overall cost & complexity of your project.

So lets work with what you have:

With a th-350 & 4:10's your first gear ratio is going to be 40.5:1.
Highway RPM's w/those 37's @ 65mph should be around 2450, which is a bit below recommended "best fuel economy" standards and way/way below best drivability for towing & power.

All according to this chart:
http://www.4lo.com/calc/geartable.htm


Also keep in mind that not knowing your budget, mechanical skills or weather or not you have access to a shop w/all the tools to work in makes giving any kind of real advice sketchy.

[SeventyOne]

I want to keep this build as simple as I can so leavng the OD tranny out does that.

So with the 4.10s I will be underpowered on the highway - but I won't see a lot of highway miles and to be honest getting these trucks up to 65 can be downright scary. I see 55-60 being topspeed until it feels safe.

My real concern is getting going from a stop would 4.56 be a better overall ratio? And since you brought it up I am now worrried about the braking system. No point in being able to get going if you can't stop.

[Critter]

Just another opinion here, so take it for what its worth. As Jtrux mentioned I have a 350, th350, 3.73 drive train with 35" tires. The 350 small block was the original engine and is old and worn out (aka not a lot of HP). I drove my K5 around like this for a year while I collected parts, its currently torn down for rebuild/restoration. Anyway, it drove around town pretty easy and the highway RPM was nice and low. Having said that, I plan to go with 4.10 after it is rebuild because the 3.73s were just a little too high geared. If I planned on doing any serious wheeling with it, I would have definitely gone with 4.56s. From the way you describe your driving I would think that 4.56s with your 37" tires would be about right.

As far as the axles go, the general rule of thumb is that stock 1/2 ton axles can't handle anything bigger than 35" tires reliably. A lot of people do it, but just plan on eventually breaking something. My suggestion for you, when considering what you want to do and what you want to spend, is to use your 383, rebuild your TH350, get a 14 bolt full floater and stuff some 4.56s in it, and convert you front Dana 44 over to 8 lug. They aren't hard to convert and it will give you tougher outer bearings and bigger brakes. I would also convert the rear 14bff over to disc brakes. Both of these conversions are talked about extensively all over this site, just run a search. Once again, this is just one man's opinion...a man that has worked on a lot of trucks, but doesn't know much about rock crawling/hardcore off-roading. In the end it’s your truck, so build it like you want.

[SeventyOne]

Ok found a 14bolt out of an 86 Suburban:

http://sfbay.craigslist.org/sby/pts/1107633406.html

That should do it right? Move the spring pads and shock mounts, swap on some discs and get some 4.56s...

Swapping the D44 over to 8 lug requires a different outer wheel bearing and rotor (As far as I know) - from here is there a new/larger caliper that will mount to my existing caliper bracket or do I need to find one from an existing 3/4 ton D44?

[Critter]

Originally Posted by SeventyOne

Ok found a 14bolt out of an 86 Suburban:

http://sfbay.craigslist.org/sby/pts/1107633406.html

That should do it right? Move the spring pads and shock mounts, swap on some discs and get some 4.56s...

WOW, that's a pretty good price. The only other thing for the rear end would be that your old driveshaft and the 14bff use different Ujoints. You can get an "adapter" Ujoint, but if you lift it six inchs you will probably need a longer driveshaft built anyway. Just get the appropriate yokes put on the correct ends.

[vtblazer]

Originally Posted by SeventyOne

So with the 4.10s I will be underpowered on the highway -

It's only a chart, take it for what it is but I don't believe it's 'only' talking about highway use.

Originally Posted by SeventyOne

Ok found a 14bolt out of an 86 Suburban:

Another option is to find a CUCV truck, you'll get both axles & drive lines in one package.

[Jtrux]

Originally Posted by vtblazer

Another option is to find a CUCV truck, you'll get both axles & drive lines in one package.

Great advice, although if I found a running one i'd want to keep it for the novelty of having a big camo'd 4x4 to run around in.

[SeventyOne]

I think theres a cucv truck around my town for sale.

D60 front, 14b rear, 6.2 diesel, olive drab paint, big ol' military brush guard... $2500

[vtblazer]

Originally Posted by SeventyOne

I think theres a cucv truck around my town for sale.

D60 front, 14b rear, 6.2 diesel, olive drab paint, big ol' military brush guard... $2500

Go check it out, it will have those 4:56 gears your looking for.

[SeventyOne]

Originally Posted by vtblazer

Go check it out, it will have those 4:56 gears your looking for.

If i was looking for a truck to wheel I would go for that one...I don't need to have a truck that needs parting out in addition to building a blazer.

What about this pair of axles?

http://sfbay.craigslist.org/eby/pts/1120303644.html

[Jtrux]

Originally Posted by SeventyOne

If i was looking for a truck to wheel I would go for that one...I don't need to have a truck that needs parting out in addition to building a blazer.

What about this pair of axles?

http://sfbay.craigslist.org/eby/pts/1120303644.html

Perfect for your application.

[SeventyOne]

Sweet, I am checking if the perches are 40" apart so it will an easier swap.

[SeventyOne]

Originally Posted by Jtrux

As far as the axles go, 3/4 ton axles do offer alot in the form of braking. Bigger rotors up front and bigger in the back. The rear will be a 14 bolt full floating axle if you're looking for a big, cheap axle with tons of aftermarket support. A disc brake conversion is cheap as well. You can upgrade the front 6 lug dana 44 but there's not a whole lot you can do for the stock 12 bolt cheap.

I have a question about this:this quote is taken from

http://www.4wheeloffroad.com/howto/3084/index.html

The only parts really changed to make the Dana 44 a 3/4-ton are the brake rotor and hub. You can either buy these new as a unit, which comes with the studs pressed in, or find a used pair, which is much more economical. The original 1/2-ton brake backing plate and caliper are retained.

So my question how does this equate to better braking if the same 1/2 ton caliper is used?

This also leads me to think that a D60 is needed upfront for a true brake upgrade - but then my cost might as well have another $800-1000 on to it.

Then it got me thinking there is no reason to go 8 lug if I can get rear discs (like I would have swapped on to a 14bolt) on my 12 bolt...like from one of these two sites:

http://www.blackbirdscustomtrucks.co...x7.html#610&12

http://www.ruffstuffspecialties.com/...roducts_id=364

I just want to get all the options out in front of me...I would be doing this swap in order to get better brakes (and a SOLID rear axle is a plus too) but to me it seems the front is just changing from 6 to 8 lug...

[Jtrux]

I'm pretty sure the 3/4 ton rotor is larger in diameter which would mean more mechanical leverage for the caliper since it is placed at a further distance from the hub.

[SeventyOne]

hm maybe you're right jtrux... But I have done some more research and plan to do the 1 ton booster and master upgrade which is basically bolt on to a 71-72 blazer. There is a write up I found on this site with pics.

I think I will start the tear down this weekend.

[SeventyOne]

So it's been a couple months and I made some progress...I didn't get started on the build until July 13th but at this point I am ready to take the body off the frame once I make all the necessary disconnections. Pretty good I think for a couple hours after work a few nights a week with my brother to help turn wrenches (and air tools help ).

Front clip is off, bumpers, doors, top, tailgate, interior is (90%) stripped and this leads me to my question - what else needs to be removed before the body comes off?

body bolts
fuel lines
electrical connections
brake booster
heater lines
rear shocks?
etc?

Any tips or tricks with these things?

Pics to come tonight when I get them off my camera - before, during, and after.