is there really any noticable difference in boring a 302 30 over? engine is a stock 68 302, 9.1 compression. was planning on using some 30 over flat tops after the boring is done,along with the stock heads with a little port work,and just the stock internals for now.is there any advantage to any of this?i'm sceduled to drop off the block saturdy morning to have the work done,but now i'm scrambling/hunting for info to see if it's even worth it.any help/info/knowledge is greatly appreciated.
thanks for the reply.will there be any noticable difference,or just a good start for add-on parts later?
You gain a couple cubic inches, but the reason for boring is to get the cylinder round again on an old worn engine. That is pretty much the only gain - back to round again.
cyl bores get conical in shape from top to bottom (wider at top/narrower at bottom)from use/miles.That is the primary reason for boreing as acornridgeman stated.
well an overbore is about useless then.this was a great running engine,with great compression,as i just tore it down to freshen it up,and was going to have it bored,since it was already tore down.
i was considering having the same done to my 351w block,but then i would have to modify my 6901 headers,and my budget is very thin right now.i'm trying to find a way to get the most bang for the buck without doing an actual stroker,either on the 302 or 351w.
Did you mic up the block? They all get worn. If the taper and bore are within factory tollerences yet - all you need to do is a good cross hatch honing (you can do this yourself) and you are good to go!
block has been checked out,and within factory specs/tolerances.i know it will need it for the new rings,but it still has the factory cross hatch pattern in the bores with no lip on top of the bores.engine came from a low mile 68 torino that was more or less rotted in half.
thanks for the info guys since there's no real benefit of having it bored,i'm just going to leave it stock for the time being.any good suggestions for a good lumpy cam that will not collide the valves into the pistons?my mav has man.brakes and no air cond.
what...carb./intake/exhaust manifolds/transmission/rear gear...are you running...all this is factored in when choosing a cam...
If you aren't going to bore the block be sure to remove any slight ridge at the top of the cylinders - otherwise the ridge could bind the rings or break them or the top ring bottom land might break.
600-650 cfm,basic edelbrock performer,6901 headers,either a c-4 or 4 spd.,and 411 gear w/ trac loc.basically an around town stop light to stop light car.i like the 351w idea but from what i've been reading the headers are a kill-joy. mav has no p/s,no power brakes,and no a/c. love the sound of a lopey cam,but also want something that will work together with everything else.
If the machine shop has measured and passed it then dont bore it. The thicker the better for our little cylinder walls.
