I have a 1970 Chevelle Malibu Cloned SS. It had a 400 small block with cast iron heads and aluminum intake, since then I have put in a 454 all cast iron with aluminum intake. I want to know the weight difference of a Fully Cast Iron Big Block vs. Small Block. I have tried to find info on the internet but I have not found much of anything. I put big block springs in the front and ever since it feels like I have a big boat ancor in the front of my car. I love the power but I find it is way too easy to bottom out. I am considering Aluminum Heads for the big block and would like to have the small block weight with the big block. Please only respond with weight if you know for sure. Here is what I found for cast iron BB and SB engines

Big Block 685lbs
Small Block 575lbs

How much do Big Block Aluminum Heads Weigh Loaded?

Any Help would be appreciated. Thanks

Get some of the custom made springs for your car. I got my springs custom made for my 70 clone from www.coilsprings.com. No issues with bottoming out and I went from a small block to a 454 (all IRON), no aluminum anything. First set of springs I got, from the generic parts houses, were so stiff I couldn't compress the front end. They had to go.

My new custom springs are also cut for a 1" drop in the front so if they were going to bottom out I would think they would really bottom out.

I also put new bushings in everything up front as well.

You could expect to lose about 100+/- lbs!

so, a big block with aluminum heads weighs as much as an iron headed small block?

I can tell you this. A 396 bare block weighs about 220 lbs and a 427 bare block will weigh about 10 lbs less. At least that's what I found when I weighed
three pre-1970 blocks.