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<blockquote data-quote="Dave70968" data-source="post: 3101093" data-attributes="member: 13624"><p>A 350 was initially at the top of my prospects list; it looks like my initial reading was good.</p><p></p><p>Fortunately, I have nothing but time on my hands; I'm not even looking to start for probably a year, though I'd certainly pick up the right core if I found it and stick it in the garage. That said, what should I look for to separate the good cores from the bad cores? Anything I can look for without taking the heads off, or do I need to actually inspect the bore? Any particular danger signs to watch for? I'm guessing a scuffed or scratched bore is an obvious danger sign, but what else?</p><p></p><p>So I've heard, and I'm certainly interested in it conceptually, though I don't necessarily plan to use all of the available power. I'd love to have something that I derate in normal use by 25% (number pulled out of thin air). Again, looking for longevity as much as fun.</p><p></p><p>Added to my list.</p><p></p><p></p><p>I had to go do a little reading on the metallurgy, but why do you dislike hypereutectic pistons? They seem to have some significant advantages (not arguing; I want to understand).</p><p></p><p>As to compression ratio, that sounds like it's up in the range that requires premium gas. I'd like to avoid that. Aviation has the same problem, with the additional issue that autogas has a higher vapor pressure than avgas, so even with low-compression pistons, you just can't use autogas up above about 8,000-10,000 feet without problems; avgas is 100 octane, "low lead" (if memory serves, about half the lead the old 100 octane had). We're in a serious crunch right now trying to find an unleaded fuel that'll work across the fleet, but even with some showing promise, it's still ~$5/gallon.</p><p></p><p>I want something that'll run on anything from premium to Uncle Jed's moonshine if it comes down to it (facetious, but close).</p><p></p><p></p><p>Understood completely. I doubt I'll be doing the honing myself; I wouldn't mind, but I expect it's a high-precision job beyond my skillset and toolbox, so that'll be between me and the machine shop.</p><p></p><p>This seems like the place to discuss overboring; given that we're only talking thousandths over, I assume that's not so much about increasing power in and of itself as it is about presenting a new, unscratched cylinder wall? And slightly larger rings to match the overbore?</p><p></p><p></p><p>How long is break-in? In aircraft engines (say, a Lycoming O-360: four-cylinder, opposed-four configuration, 360 cubic inches; about 180 HP), break-in can be ~25 hour (or more), run at 75% power or more (redline is typically 2700 RPM). We also typically run straight mineral oil rather than ashless dispersant for break-in.</p><p></p><p></p><p></p><p>Yeah, that sounds more like a race engine than what I had in mind. Not that there's anything wrong with that, just not the application I'm thinking for this build. I'm looking more for not-quite-daily-driver to moderate off-road (think hunting Jeep suitable to go to either side of that application).</p><p></p><p></p><p>I appreciate the links! I'll definitely get to reading.</p></blockquote><p></p>
[QUOTE="Dave70968, post: 3101093, member: 13624"] A 350 was initially at the top of my prospects list; it looks like my initial reading was good. Fortunately, I have nothing but time on my hands; I'm not even looking to start for probably a year, though I'd certainly pick up the right core if I found it and stick it in the garage. That said, what should I look for to separate the good cores from the bad cores? Anything I can look for without taking the heads off, or do I need to actually inspect the bore? Any particular danger signs to watch for? I'm guessing a scuffed or scratched bore is an obvious danger sign, but what else? So I've heard, and I'm certainly interested in it conceptually, though I don't necessarily plan to use all of the available power. I'd love to have something that I derate in normal use by 25% (number pulled out of thin air). Again, looking for longevity as much as fun. Added to my list. I had to go do a little reading on the metallurgy, but why do you dislike hypereutectic pistons? They seem to have some significant advantages (not arguing; I want to understand). As to compression ratio, that sounds like it's up in the range that requires premium gas. I'd like to avoid that. Aviation has the same problem, with the additional issue that autogas has a higher vapor pressure than avgas, so even with low-compression pistons, you just can't use autogas up above about 8,000-10,000 feet without problems; avgas is 100 octane, "low lead" (if memory serves, about half the lead the old 100 octane had). We're in a serious crunch right now trying to find an unleaded fuel that'll work across the fleet, but even with some showing promise, it's still ~$5/gallon. I want something that'll run on anything from premium to Uncle Jed's moonshine if it comes down to it (facetious, but close). Understood completely. I doubt I'll be doing the honing myself; I wouldn't mind, but I expect it's a high-precision job beyond my skillset and toolbox, so that'll be between me and the machine shop. This seems like the place to discuss overboring; given that we're only talking thousandths over, I assume that's not so much about increasing power in and of itself as it is about presenting a new, unscratched cylinder wall? And slightly larger rings to match the overbore? How long is break-in? In aircraft engines (say, a Lycoming O-360: four-cylinder, opposed-four configuration, 360 cubic inches; about 180 HP), break-in can be ~25 hour (or more), run at 75% power or more (redline is typically 2700 RPM). We also typically run straight mineral oil rather than ashless dispersant for break-in. Yeah, that sounds more like a race engine than what I had in mind. Not that there's anything wrong with that, just not the application I'm thinking for this build. I'm looking more for not-quite-daily-driver to moderate off-road (think hunting Jeep suitable to go to either side of that application). I appreciate the links! I'll definitely get to reading. [/QUOTE]
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