0ver Boring a LA 318, how much is poss for more cubes ?


Senior Member
Dec 6, 2013
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San Diego
Look at boring only for cleaning up bores for rebuilding. The extra displacement is negligible in a non-racing application.

Find a 360 if you can. Or a stroker crank. If those are out, consider a cam swap. Avoid the temptation to go big. What Yanks call an RV cam will suit you best. within the limits of max lift on your springs and valves, you want cam with the most lift for the shortest duration.

I haven't looked at LA engines but Hughes has some aggressive cams for RB with low duration (under 220 @ .050) and high lift (near 0.500 at the valve). Max lift on an LA is gonna be less but duration will be similar. You probably want to be conservative because you can't make up for cam with cubes.

Here. Look at these first two.

Hughes Engines
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Well-Known Member
Nov 15, 2010
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Eastern CT, 2 stoplight town, Columbia, CT
As was mentiined - the bore size is almost irrelevant for what you want to do. Thinner cylinder walls means lost ring seal and lost power. I would leave the bores at the smallest size that allows you to achieve a straight, round bore with the right finish for the rings being used. Instead, have the crankshaft offset ground to increase the stroke. You should be able to turn the journals down .020 and get .040 more stroke (you end with 3.35) which will give more torque straight off idle. It's not a massive amount, but more power of the kind you need in that car. It will also give any piston more static compression in your block, adding to output. That's what I'd do.