Quite simply? Marketing. 5.0 is a big round number, therefore it is bound to sell better than 4.9.

Although there is this from Wikipedia:

In the 1980s the 302 became more commonly known as the 5.0 Liter, although its metric displacement (4942 cc) accurately rounds to 4.9 L. It is speculated[who?] that Ford used the "5.0" moniker to distinguish the 302 from the 300 cu in inline Six, which was known as the 4.9. Despite its advertised displacement, some automotive magazines[who?] referred to the 302 – correctly – as a 4.9 liter engine.

 

wow this discussion got a lot deeper than I ever suspected it would. I like to learn but I hate math I think I will check with my local sign shop also and see what they can do for me. 20 bucks sounds a lot better than what I have been able to find on the net.

 

I believe classics industries has the 5.7 decals, but not sure how much, and they have the HO and liter as well. my car was repainted and they covered the 5.0 H.O. so I will be replacing soon.

 

LOL, i always thought 5.7,5.0 ect, meant like 5.0=5000cc LOL. or does it mean that. Cuz the 3.8L people always say 3800.

 

Technically it does. But, you try building an engine that displaces exactly 5000cc. See how that works for you

It's all funny naming shenanigans to make things sounds bigger and more powerful~

 

ebay offers sticker-like badges for the rear bumper and side skirts, but the only 5.7 are for tpi. i was told a graphic shop or a body shop could have a better lead on where to get badges made or ordered from. i was going to stroke my 350 to a 383 and i was going to get 6.2L tuned port injection badges, but now im just gonna stick with the regular badges for the 305 (dont show displacement) so no one knows for sure what im running