diskfailure01

So Im driving by a used car lot and I see an 88 or 89 prymer mustang with 306 rebuilt on the windsheild. WTF is a 306?

PRO50SC

Engine size

Stevens91gt

yep engine size..it's bored over..uhh .040 i think

diskfailure01

So that means that since mine is bored at 40 over its a 306? Hmmm never heard it advertised like that before. All I have ever heard it the "bored at 40 over" deal. Interesting...

Stevens91gt

yep you have yourself a 306

congratulations..haha

so you had never heard of it as a "306"?

diskfailure01

Nope. Im still learning all of this stuff which is fine. So how much of a diffrence does it really make? When I bought the engine out of a wrecked 5.0 Cobra I researched and everyone said to get it bored to 40 over and put in bigger pistons which I did. I understand the 0.40 but does it reall make a diffrence?

XPBaller

.40 bore you wont see much gains. Its more-or-less to cleanup the cylinder walls.

smbikes

306 in 20 over i thought and a 40 is a 308

Stevens91gt

60 over is a 308 i believe

and nahh i've heard that every 1 is around a hp gain

so it's like 4 hp more

ckyguy68

.30 over is 306.