Are they any good or are they a waste of $8 for some springs and weights?

I'll let you know soon as I'm about to install the Crane kit.

The springs seem very useful. I've not seen an HEI kit that had usable weights. If you find one that works, please let me know!

Well most of them come with them so I figure "Why not just use them?"

Also is it necessary to alter the base so that the weights can advance more? I'm hoping this is a "drop in and go" kit w/o having to modify anything.

I see they even come with bushings...what's with those?

the spring are a great tuning device for a new curve but the weights are really useless......use the stock hei weights but taylor you curve with the new springs.........the bushing help control the amount of mechanical advance for most performance cars like to be in the 16- 20 degree range for initial and 36 or so total.......most hei units have 20 - 25 degrees mechanical and that needs to be closed down shorter to about just 16 degrees.........i myself use just the springs in the kits and the rest of the stock hei unit.......i just weld my slot closed to my liking until i get the mechanical spread im looking for instead of useing bushings.......charting your curve is always good advice for you want a smooth curve.......sometimes your combination of spring will allow the timming to spike.....say 20 degrees at idle 700 rpms to 30 degrees at 900 rpms ........and this would cause some engine to go into pinging..........you want to make sure however the timming from park idle to in gear idle doesnt change........on some combinations of springs you can be in park with an idle of 1000 rpms with 20 degrees of timming and pull it into gear and it drop to 14 degrees of timming and you are wondering why your rpms dropped to 500......and the engine sounds like crap.....so the timming needs to be the same from park to in gear.....this help to keep the rpm drop from park and in gear low say 250 rpms....compared to a bigger drop of 500 rpms if the timming retards itself...........