Building an inline 6 Chevy 250 engine
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==Introduction== | ==Introduction== | ||
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| + | The Chevy inline 6 has been around in one version or another since 1929 until 1988 in domestic vehicles. The Chevy straight 6 250 cid engine was brought out in 1966. It has a 0.280" longer stroke (3.53") and the same bore (3.875") as the 230 cid straight 6. It boasts a 7 main bearing bottom end- quite an improvement over the previous generation inline's 4 main bearings. | ||
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| + | ==Some things to consider== | ||
| + | Building a straight 6 250 is not any harder to do than any other inline 6, be it a Ford or Chevy, GMC, etc. Parts aren't as common for the inline 250 as they are for a SBC, but there is info and quite a few suppliers for parts, as well as places that cater to almost nothing but the Chevy inline 6 engines. | ||
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| + | The inline 6 Chevy 250 should not be compared to a SBC engine. Besides the obvious differences, they share practically no parts w/the V8 engines. Because of this fact expect it to cost more per horsepower than a Chevy V8. The reward is this is not a "belly button" engine; instead it is considered "old school" and has cred because of what it ''isn't'' as much as for what it '''is'''. | ||
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| + | To the right person, building a 250 Chevy 6 can be just as rewarding as any other engine, and if parts are selected in a coordinated manner and the engine used in a way that accentuates its strong suits- like dependability and good lower RPM torque production for its size- a very satisfying result can be had. | ||
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| + | It's a fool's mission to build a NA inline 6 like the Chevy 250 expecting to run amok on all the SBC and SBFs out there. Not only will the results be very humbling, but the amount of money that would need to be spent in order to go toe-to-toe with a SBC 350 will break most people's budget all to hell. So instead of trying to beat the world, it may be much more satisfying to build a Chevy 250 to make around 0.8-1 HP/cid (~200-250 HP), and revel in the uniqueness of it and enjoy as torquey, strong running engine that has a sound and look all of its own. | ||
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| + | Given enough time, effort and cash, an inline Chevy 6 can make >/= 2 HP/ci naturally aspirated and far more than that using a turbocharger. Superchargers can also be used, but the turbo is the preference of many who are going for boost. | ||
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| + | ==Engine ID== | ||
| + | ===Casting numbers, date codes, and suffix codes=== | ||
| + | Obviously casting numbers and VIN stampings can be a big help. Chevy inline 6 casting numbers can usually be found just above the starter on the passenger side of the block. | ||
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| + | On the block there will be foundry ID codes, for instance "CON3". This is no help in ID'ing the engine. | ||
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| + | There may be a date code cast into the block. Example- "A 30 2": Jan 30 of a year ending in 2. If the engine is a 250, that would be 1972. | ||
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| + | The suffix code (also called the "application" code) will be at the end of a string of letters and numbers (that's why it's called a suffix). The suffix string is usually a letter followed by a date code, followed by 1, 2 or 3 letter code. This is found in the area near the distributor, above the fuel pump. The suffix string of letters/numbers are always stamped in, not cast into the block like the date code or foundry ID code. | ||
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| + | There may also be a partial VIN number stamped in a separate string of numbers near the suffix string. If the block is missing the suffix and partial VIN, there's no way to know what the engine might have come in originally, unless there were other external clues like a carb w/a governor on it (would be on a heavy truck or bus), or if it had a large bellhousing and a HD "granny low" trans (also HD truck/bus application). If the crankshaft has a pilot bushing in it, that would mean it had been used w/an auto trans- although this could have been added later.<br> | ||
See '''[[Building an inline 6 Chevy 250 engine#Resources|below]]''' under '''Resources''' for sites that have casting number info. | See '''[[Building an inline 6 Chevy 250 engine#Resources|below]]''' under '''Resources''' for sites that have casting number info. | ||
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