What's the deal with angled lowering blocks?

I've got a set of 4 in. "angled" lowering blocks? I've seen them advertized for S-10's & other modern stuff. Are they useable on an American 50's car? WHAS THE DEEL?

thanks.
-r

 

They have to be angled to keep the pinion angle correct.Otherwise the U-joints would be bind up.

 

Yeah, I figured it had to do with pinion angle, but what are the advantages (if any) to angled blocks vs. regular rectangular style. It seems that all the blocks advertised for 50's cars are the rectangular/ non-angled style.

I guess what I'm asking is...will I do grievous harm to my rearend/u-joints/anything else you can think of with angled blocks?

 

If your just going to lower the car and all the major suspension components are stock, I'd say that off the shelf rectangular blocks would probably work. Remember that when you raise the differential up on 1,2 or 3" blocks, it will often change the pinion angle. After you lower the car, check the angle and if it's not in the ball park, you can always mill an angle onto the blocks after the fact, as long as there is some material to work with. An alternative is to buy some Moroso angled shims to put between the spring and the lowering blocks. There not my first choice but if your short on shop equipment, an easy fix. One thing for sure, if the pinion angle is out of tolerance to the extream, you'll puke the U-joints in a heartbeat!

Shoe

 

Also check if the blocks are too wide, lots of 50's cars have 2" wide springs, many modern car springs are wider than 2".