lameusername

Ok, don't laugh because I don't know what I'm doing and or much about engines but I love my 86' Iroc.....but if I were to have my 305 bored out to a 327 is it now a 327 or is it still a 305?? I also want to know just how powerful can a 305 be...if you need to know, I have TPI and would like to keep it.

Atilla the Fun

You can only bore a 305 to 315 cubic inches. And even if you did, you still refer to it as a 305, because it will still behave and respond as a stock-bore 305. Also, even if you could keep boring it, it still wouldn't be a 327 because real 327s had a 4" bore and a 3.25" stroke, while you would have a 3.867" bore and a 3.48" stroke.
Just keep driving the 305 while you find a 350 you like.

lameusername

Well, now I have another question.....if a 305 is bored to a 315 and it would still respond like a 305 then why do people bore out engines??? I take it that it applies to a 350 bored out to whatever people bore them out to??? Is there a gain in anything when you bore an engine out????

Atilla the Fun

In the days before computer controlled fuel delivery, engines tended to wear the cylinders. In 100,000 miles you could have so much bore wear that the engine needed to be bored 0.030" oversize just to get the bores back to truly cylindrical, necessary for adequate ring sealing.
With the typical SBC V8, a 0.030" overbore might net you 5 ft-lbs of torque.
Major increases in bore diameter can really add cubic inches and unshroud the valves, but those big increases come from replacing your small-bore blocks with blocks cast correctly for large bores.
A 305 block cannot be bored to 4.000", there would be literally no cylinder iron left. You'd "hit water".