Coil spring adjusters
 

Do they work? The type I am referring too is the ones you clamp to the coil and it compresses it.

Idk good question though I am interested in opinions and real experiences who had them? I would think that the spring is set to safely work at one rate of compression based on the vehicles weight. Is compressing it going to change its reliability or stability and make it unsafe?

They might work, but, IMHO, they are not a good idea.
My 2 cents, don't.
You might need to cut a bit off the spring, or get another one.

I do not like the idea of compressing the springs to get a stiffer ride or cutting out a section of the spring. Your best bet is almost always to get a performance suspension spring set. Depending on your year Vette this will lower the suspension between 1/2 to 1 inch. You will need to get an alignment after installing a kit like this because it lowers the car and changes the dynamics of the suspension.

Such as this to improve the handling of the car. It is fairly inexpensive and a better solution.

http://www.ecklerscorvette.com/corve...1963-1979.html

There is no guarantee that buying front springs to lower the ride height is going to put the stance exactly where you want it to be. While I agree the spring compressors are a bad idea buying higher rate lowering front coil springs could still need to be trimmed to get the look you're after. Unless you do something like coil overs or stock car type hidden ride height adjusters it could be trail and error.