Springs in front with a bbc

[Big70]

So I took my small block out of my 70 own and put in a 454. My buddy said he thinks I need heavier duty springs in front for the wait and so it will be able to ride good... What is your guys thoughts on this? I don’t see 67-72 springs that are heavy duty and ones that are not?
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['68OrangeSunshine]

I used to run a '67 K/10 Suburban with a 454 the PO had shoehorned in. '67 4X4 1/2 tons had just 2 leaves of tapered leaf springs. Twenty-six years later [I bought it in '93] metal fatigue would have allowed them to sag. Original engine was possibly a 283 which would have weighed about 150 lbs less than the big block. PO did nothing to beef up the suspension.
On the freeway at 70-80 mph, that doghouse would jump around like a Go-Go Girl in a cage.
On a coil spring truck, you miight be able to replace the OEM front springs with heavy duty ones.
[Although the trend is to put in weaker, or cut-down, front coil springs to get a lowered effect.]

[kwmech]

Find another set of stock springs and make it a 3 or a 4 pack set. I am doing this soon to my suburban for a lift, plus adding on a winch and bumper. And actually there is closer to a 200-250 pound difference between the small block and big block, unless there is a lot of aftermarket aluminum on either

['68OrangeSunshine]

Originally Posted by kwmech

Find another set of stock springs and make it a 3 or a 4 pack set. I am doing this soon to my suburban for a lift, plus adding on a winch and bumper. And actually there is closer to a 200-250 pound difference between the small block and big block, unless there is a lot of aftermarket aluminum on either

That would be a good solution to uprating my '67 K/10 Sub. The PO did give me some 4 leaf Rancho front springs, but they would not work on a '67-'68 frame without relocating spring perches and shackle locations. Another solution [as advanced by Arizona Spring -- a local shop] would be for them to reheat and recurve the originals and maybe add a helper leaf.

My engine weight calculation is based on a cheatsheet I have compiled, based on engine weight stats I have gleaned off the internet. It is by no means accurate, and I welcome corrections.

The OP has not stated what model his truck is, only the year MY 1970.
Longbed, shortbed, 4x2, 4x4, coil or leaf spring? We need more info.

[kwmech]

You keep the same main leaf and add the bottoms ones as needed and/or cut the eye of the spring off as needed. I make misc spring packs all the time.

[Mike C]

Early Classics has big block lowering springs which have a different rate from the small block springs.

I would think small block 3/4 ton springs would work in a big block 1/2 ton truck, but replacement big block springs shouldn't be hard to come by.

[tx71smallblock]

interested as well, im thinking about making my 70 2wd bbc powered

['68OrangeSunshine]

Originally Posted by Mike C

Early Classics has big block lowering springs which have a different rate from the small block springs.

I would think small block 3/4 ton springs would work in a big block 1/2 ton truck, but replacement big block springs shouldn't be hard to come by.

I don't have a 3/4 ton so I dunno really, but I'd guess the spring mounts are different.

[Mike C]

You never said anything about what your truck did have to help. The first posts were talking 4x4. Telling us what you did have would help. But...

The 1/2 ton and 3/4 ton trucks are physically the same dimension. The rates are not the same but can be swapped with impunity from 1/2 to 3/4 and back. That's true if you have a leaf spring rear or coil spring rear.

[70STOVEBOLT]

I took a 250 out and put a 402 in with the stock, factory coil springs on my 70 and it rides the same, and at the same height.

[toolboxchev]

They did make a Heavy Duty front coil spring option on the 3/4 ton trucks.

[sick472]

Eaton Detroit Springs...

http://www.eatondetroitspring.com/findmyvehicle/

shows the heaviest coil springs are for a 402 for the 1/2 ton 2wd and two leaf rates (440 $ 660 lb/in) for the 4x4 (350 cuin only). The coils are for "with AC or without" these would be the best right off the shelf for coils and the higher rate leafs will be the best off the shelf. You can even fanagle the ride heights, a 1" higher ride height spring may work under your heavier load to have the same ride hieght compared to the original height, you never really know until you try.

Now, I have worked with them before and they will custom make your spings to be more heavy duty if you care to go that way for a bit of extra cash. I would give them a call and at least learn from them what they recommend. You will have to give them some engine/drive train weights to work with (before and after the mod).

Springs can be a lesson in patience because messing with the front springs may/will change your rake and you may then have to change your rears and it rarely goes without some trial and error. I typically end up with an extra new set of springs to trade off.

[Ironangel]

LMC has the coils for BB as well as SB, front and rear as well as front and rear 4 spring kits depending on what motor and even variable rate coils... http://www.lmctruck.com/icatalog/cb/full.aspx?Page=62
I ran the stock 1/2 ton SB springs in my 1/2 ton BB truck with no ill effect in handling. The BB did squeeze another 1" drop down but they had plenty of room to function with no coil binding. The softer rate actually helped plant the rear on high rpm launches at the track...If you dont have a sway bar up front then you will need the heavier BB springs...Im referring to 2wd C/10's w/coils only...PS Mike C is correct in that 3/4 and 1/2 ton springs interchange. They're practically identical although the 3/4 ton springs are a larger diameter rod than the 1/2 tons. I installed a set of 3/4 ton coils in the rear of my other 72 C/10 towing rig. It already has a set of factory overloads and I installed a heavy 14,000lb class-4 hitch...So it thinks and pulls like a 3/4 ton...