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bore .030 over. whats it mean

6K views 17 replies 11 participants last post by  ShaunT 
#1 ·
When someone says they bored there 302 over .020 or a 289 over .030... What does that mean and what does that entail? The require an engine pull out of a car? Thanks...
 
#9 ·
One thing that most shops do wrong on the boring process is bore them to size rather than leaving some stock in there for the hone to remove so that the honed cylinder has clean base metal when finished.

For instance, if my finished bore needs to be ready to run at .030 over, then I bore it .026 and hone the other .004 out of it because the boring bar makes a hell of a mess of the cylinder... torn/fragmented metal. (When you look at a cylinder under 40X magnification after a boring bar has had its fun with it, you'd see what I mean.) Under magnification, the cylinder wall surface looks like a Grenade hit it. Simply honing a couple of strokes to put some cross hatch in the bore won't clean all that out and the hone will be very shallow as well thus lending itself to very poor oil retention and hence a very short lived ring with poor ring seal/oil control.
 
#12 ·
lol



hey remember the good old days before aftermarket blocks were readily available and every one was taking 427s and 454s and filling the water jackets with concrete filler and boring them .100 and even .125 over? haha fast burn out make a pass and shut it down! hey is any one running a block like this now?
 
#16 ·
hey remember the good old days before aftermarket blocks were readily available and every one was taking 427s and 454s and filling the water jackets with concrete filler and boring them .100 and even .125 over? haha fast burn out make a pass and shut it down! hey is any one running a block like this now?
What is wrong with boring a 454 block .100 over?
 
#13 ·
Oh I remember like it was yesterday. I also remember well the days when anything you needed for a cylinder head required chopping up a factory head and doing everything to it in the port that you could imagine including welding and epoxy, etc, because aftermarket heads did not exist.
 
#14 ·
Bore is how wide the cylinder is. Stroke is how deep.

When you bore it, piston gets wider.

When you stroke it, you make the piston travel down further with differant rods, crank.
 
#15 ·
Thanks all, that answers my questions. Yall are fan f**kin tastic
 
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