Big Block Springs

[Street Sweeper]

OK - I have been gathering parts for a big block swap in my '65 suburban. I appreciate all the information you guys offer up here - it has been invaluable. I think I know the route I'm going to take with the motor mounts, position (front to back), headers, etc.

What I'm trying to find out is if the weight of the big block will require a change in the front springs. I'm changing out my front end and adding drop spindles and disc brakes before I do the BB install. While I've got it all apart i'd like to go ahead and make the needed spring/shock upgrades if necessary. I know some of you BBC guys have bagged trucks. For the ones with spring suspensions - did you change the springs? Does it lower the truck any more with the BB and the standard springs?

Thanks in advance for your help.

[steverino66]

Here's what happened with mine:
When I got the truck a 350 had been installed with original 66 springs which probably carried a six, and the front end was lowered 2-3 inches.
I swapped the whole front crossmember with an 83 and put in the 454 and the front end height is now even with back of truck.
Those newer springs carried a 350 in the 83 truck and don't look stouter or taller than the old springs, but they are.

[Captainfab]

My '66 Suburban still has the original springs. I haven't measures how much lower the big block dropped it, but it does a bit. I'm sure that the later model and dropped springs have a higher spring rate, so they may not compress as much more as the original springs.

[NF65Fleetside]

I ran a 454/350 combo in my previous 65', it had a 350 in it before with cut stock coils and shocks. After the swap the front went down just a tad, nothing major. Truck was a daily driver and I didnt notice any difference in clearance and ride quality nor understeer at all. You should be fine with any new set of springs, stock height or lowered.

[rockvette]

When I installed a 502 c.u. I put a set of 1 ton springs to make up the differnce because of the extra weight.It put the truck at the proper height

[Street Sweeper]

Thanks for all the input. Sounds like if I go with a new (not worn out) set of springs on the front it probably won't make a huge difference in the stance (maybe just a tad lower). I'm trying to get the front end a little lower - just not too much. This gives me a good idea of what I need to do. Thanks.

While I have you BBC guys' attention - are you also running front / rear sway bars? (especially you suburban / panel BBC guys)

[Rich 5150 69]

From what I understand is that the `67` to `72 big block springs (factory or Napa replacement ) are one inch shorter than the small block springs. Something you might want to check out..

[Street Sweeper]

Originally Posted by Rich 5150 69

From what I understand is that the `67` to `72 big block springs (factory or Napa replacement ) are one inch shorter than the small block springs. Something you might want to check out..

Good call on the big block springs. I checked out NAPA's sight - I guess this is one of the confusing things for a rookie like me - it shows the free height to be shorter but the loaded height to be the same on each one. The design load is 500 lbs heavier for the BB springs - maybe the ride height is the same but the riding / driving characteristics would be better with the BB springs?

[Rich 5150 69]

Use those in conjunction with a 1 13/16 one ton chevy / GMC factory front sway bar, (boltup) will really roc...!