When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The story is that in the beginning (55) the SBC was called a mouse motor due to size. After shutting everyone down it was called Mighty Mouse. So any SBC is a Mighty Mouse shortened to Mouse w/ the Mighty understood.
Even much later had an interesting reaction. After shutting down everyone in Galveston (they did not know me there :cool: ) w/ my cousin riding, she said she had to see the engine. She was accustomed to fast cars, drove fast, had a boyfriend w/ a modified GTO, etc. She was shocked at the small size of Mighty Mouse.
The story I'd heard about the Rat name had to do with the valve stems sticking out at angles so they looked like porcupine quills (where the small block ones stood up straight) , and porcupine sounded stupid so it became rat.
Now that I write it down, the mighty mouse story makes a hell of lot more sense. :D
The heads are known as porcupine heads or semi-hemi heads due to the staggered and splayed valves. Basically a rat is just a slang term for a big block and a mouse is a slang term for a small block due to the obvious difference in size.