5.3L and 6.0L truck blocks question?

[Demon SS]

Are these blocks the same block? Just with a bigger bore on the 6.0L block? Or are they different blocks? I have looked in all of my LS1 info and nothing addressed this, got all kinds of cylinder head info and 5.7L block info but not much on the truck blocks. Thanks!

[mbaskett]

They are not identical.... Many of the 6.0L blocks seem to be missing bosses on the outside (motor mounts)... while they are all there for the f-body mounts, the normal alum LS1 has about 6 on each side, whereas the 6.0 blocks I've seen have 4 and 5 on the sides.

Some are also missing holes tapped and threaded for accessory mounts. (I had to make a hole for the Escalaro's alternator), but not all truck blocks need this done.

Internal-wise they do look identical. The visible oil passages look identical, as does all the internal bracing and the upper valley.

There's enough external differences to make me wonder if it is a slightly different casting design, but my intuiation of how GM works leads me to beleive that they are (for all intent purposes) the same. Just missing some bolt holes and webbing on outside ;)

[VentsWoker]

Originally posted by mbaskett
They are not identical.... Many of the 6.0L blocks seem to be missing bosses on the outside (motor mounts)... while they are all there for the f-body mounts, the normal alum LS1 has about 6 on each side, whereas the 6.0 blocks I've seen have 4 and 5 on the sides.

havent noticed this personally, but mine bolted up just fine. must be a diffrence in years

the blocks are not identical, and the 4.8/5.3's have a smaller bore than the LS1. same bore, diffrent stroke. they can be bored over to LS1 size (thank God!) you'll see ALOT more guys using these blocks in the future i predict.

Some are also missing holes tapped and threaded for accessory mounts. (I had to make a hole for the Escalaro's alternator), but not all truck blocks need this done.

this is true, but i only have 2 bolts in my alternator bracket, and it's holding up fine.

There's enough external differences to make me wonder if it is a slightly different casting design, but my intuiation of how GM works leads me to beleive that they are (for all intent purposes) the same. Just missing some bolt holes and webbing on outside ;)

the 4.8/5.3 blocks are identical. thats why they all have 4.8/5.3 stamped on the front of each of them, they simply have a diffrent 3.27 VS the 5.3 which i believe is a 3.62 stroke on the crank. but dont quote me on that. all the 6.0's have 6.0L stamped on the front, and the bore size is diffrent i.e. 4" and have cast in 317 which lables them as 6.0 heads.

the 4.3/5.3 heads casting numbers tell the story as well. 706=5.3 852=4.8 and for all practical purposes are the same head. same runners, same chambers, exhausts, just differentated between the 4.8 and 5.3 to identify them? maybe to put positive id on the shortblock? i dunno.

[mbaskett]

Originally posted by VentsWoker

this is true, but i only have 2 bolts in my alternator bracket, and it's holding up fine.



Yep, the Escalade block I did this on only had 1 hole to mount the alternator :eek: The second one was the one I drilled and tapped. Could have done the 3rd, but I felt it wasn't necessary....

[VentsWoker]

Matt, are you talking the about the blank boss on the header face of the block, or tapping the missing bolt hole on the front of the block?

[mbaskett]

On the front....

[VentsWoker]

mmhmm...