1" setback vs standard motor mount adapter plates

[Malihoochie-]

One negative if it matters to you is possible shifted frontal weight bias. Not sure how much lighter an LS is over a Gen1 SBC, might be enough to negate the forward shift although generally any weight removed from the front is perceived to be a positive change

Unless it is an aluminum block - LS's are way heavier than a gen 1 SBC.
Add in an aftermarket block and the weight goes up more.

 

[motorheadmike]

Unless it is an aluminum block - LS's are way heavier than a gen 1 SBC.
Add in an aftermarket block and the weight goes up more.

It is only 100lbs. The same weight difference between me and about 100 million North Americans. If you are looking for a more viable way to save weight in your LS swap: start in the kitchen.

 

[Texas82GP]

I'm surprised a iron block/aluminum head LS weighs more than an iron block/iron head SBC. Where is the weight difference? The deep skirt of the crankcase? The intake for the LS is nearly weightless.

 

[Malihoochie-]

A standard 1st gen sbc is 9.025" deck height (from the center of the crank to the top of the deck). A LS is 9.240", that is basically 2 x a 1/4" cast iron plate the length of the block (roughly 21") then add in the 2 upper "bars" that the little upper head bolts attach to, and finally add the skirts on each side of the block. It adds up....even more if you have a Dart block with thicker than normal cylinder wall thickness. We say the iron Dart blocks are 230# when shipping them.

 

[Cajun83HO]

I would bet a dressed iron block aluminum head LS is lighter than a dressed Olds 307.