93StreetFox

i was just wonderin if there was any machine work involved, i've never messed with the bottom end at all

86 5.0L

its machine work, more specifically they bore out the cylinders 0.030in

93StreetFox

thats what i figured, you mind as well go 347

ih8chevy

well that means increasing the stroke.

a89fiveoh

yeah i would go with the 30 over. you cant really go to big with the stock production blocks. the get weaker the more you go.

jtmustang

i just got my 306 runnin finally i have an idle video of it in general discussion

JD1969

Just want to point out that there is no power gains to be had by boring .030. It is done to true the cyclinder walls and make sure the rings have a good surface to seal agaist.

302army187

what do you mean by the rings have a good surface to seal agaist?

so with the stock 302 isent good? and the 306 is more stable?

im unsure of your meaning in this.

JD1969

When an engine gets old the cyclinders wear and go out of round or havea taper worn into them. Boring the cyclinder will true it up and allow the rings to seal better. Boring is not generally done to increase displacment, you realisicly don't get much of an increase in engine size (.030 is only 4 cubinc inches on a 302) so you not getting much power from 4 cubes.

OneFine89Mustang

go for .40 over then to a 308