I got a 455 in for rebuild that was out of a 71 or 72 442. It was a GM replacement service block for sure as the original owner of the car is the guy who owned it had GM replace the blown up 455 around 76 or 77?

here’s a pic …. Clear part I can make out is SB 2331. Can’t make out what’s stamped before the SB though..maybe large L and an I?

 

Service replacement blocks were SUPPOSED to have the original VIN derivative stamped into them. This was frequently not done. This looks more like the stamp from an industrial or marine motor, but it could also be some code used by the shop to trace back to the job number for warranty claims.

 

you’re right about frequently not done… I’ve seen a few service blocks, none had any stamping on the serial pad, all blank

I do have another block here that was from a 67 Toronado that was supposed to have a rebuilt GM engine from mid 80’s

bought it sight unseen from original owner who had the rebuild done by J Holland motors in Burlington Ontario,,paper work for rebuild was with it.

The block itself turned out to be a 400 E block bored to 4.125” , block casting number up top ground off and hand stamped with 425 cast code and the big E on the side ground down…I had a laugh at that.

I’ll post pics.

 

At a recent car show I saw a "W30" that had "F heads" - the usual E with the lower leg cut off, but this guy had gone one step further and ground off the casting number above the center exhaust ports and similarly hand-stamped the 404686 "casting" number. Yeah, THAT was convincing.

I'm curious about the E-block - any wall thickness measurements at 4.125?

 

This was done at a GM dealership. Only reason I can think of them doing this was to reuse the compete 425 rotating assembly in the 400 , including cam and .921” lifters?

you can just make out the big E on the side

 

LISB I believe is Lansing Issue Service Block.