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.

[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.

[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.

[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.

[VA72C10]

To spread the bracket just put two screwdrivers in and pry in opposite directions and it'll open up. I then bent it slightly closed to hold it to the cable so I wouldn't lose it