I've used them to good effect on a '70 Nova, with everything else properly prepared to make the car a drag car (not street driven, or only if in straight lines while on the street) they do as advertised. I can say that looking back on a car I built in '73, that ran high 11's with a SBC single four barrel I was very happy. Technology has changed since then, but if you did the same thing I did in '73, with the same car it should repeat, or go faster since heads and cams are better today.
that would all depend on the ride hieght you want on the car.my 67 sits level with out any cutting but my buddy cut 1/2 or 1 full coil off his 65 but he is ladder bared an coil overed so he sit lower than i do with stock suppention.the springs also will settle some after a little use.:hurray:
Most moroso products are just repackaged and they don't even make them. Their springs are basically 6 cylinder springs. i have bought two sets for my chevelle and both collapsed with just the weight of the car very quickly. I 4-cornered the car and had the correct spring for my application.
Find out what length you want it to be and the lbs/inch rate you need and find the closest moog or eaton spring that will work.
I have the Moroso trick front springs on my 69. They have been on it for a year now, and they haven't collapsed.
I was running the Moog 6 cylinder springs.
The Moroso springs are taller and have a bit thinner wire diameter.
There is probably a Moog equivelant, you would have to go through the Moog catalog and pick the correct height, wire diameter, OD, ID etc.
Of course Moroso doesn't manufacture these.
BTW....I street drive my car all the time. That's how it gets to the track. As you will note from my .sig.....it runs pretty dang well. The Moroso trick front springs helped with the hook.
The biggest problem I had with the Moroso springs was the handling qualities-they were too "springy" and would bottom out easily. If you just drag race, they cause the front to rise a lot, but they don't give a progressively stiffer spring like you need on a daily driver-or anything you want to avoid hitting something with in a tight handling situation.
As for the 6 Vs.8 springs....I can't agree with that. I bought (locally) new springs for my Camaro (very very close to the same) and the parts book (moog) called out the same number as a replacement spring for a smallblock and a 6 cylinder.