Stephen,
I have an all aluminum Ford 460. I bought my car used with the engine already installed. A friend who is researching the same issue tells me the aluminum 460 block is 165 lbs and the cast block is 290 lbs for a difference of 125 lbs. The aluminum block is also $4,700 according to him.
My car weighed 2740, 1300 front and 1440 rear, with a full 17 gal fuel cell. Less fuel would be 2620 lbs. The SPF website says a SPF with a 460 would be 2660 lbs so my car is 40 lbs lighter. My car has a full width 5 point rollbar, halon fire bottle system, accusump, etc, that all add weight. All told I can see that 125 lbs may be an accurate weight difference from aluminum to cast.
There are aluminum Ford small blocks as well but I do not have any info on them.
Good luck and enjoy the ride.
