Building an inline 6 Chevy 250 engine
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==Cylinder heads== | ==Cylinder heads== | ||
| − | The integrated intake head used with the 250 (except the 292 which retained the separate intake) between 1975-1984 isn't well suited for performance duty. Some pundits claimed that the integrated cylinder head resulted in increased fuel economy and NVH (noise, vibration, and harshness), its another relic of the malaise era which lasted until late 1984 when the 250 was last optioned with the Chevrolet/GMC truck/van lineup until the 4.3L replaced it. About all that can be done for a head with this intake, is the 1 barrel can be swapped for a 2 barrel by using an | + | The integrated intake head used with the 250 (except the 292 which retained the separate intake) between 1975-1984 isn't well suited for performance duty. Some pundits claimed that the integrated cylinder head resulted in increased fuel economy and NVH (noise, vibration, and harshness), its another relic of the malaise era which lasted until late 1984 when the 250 was last optioned with the Chevrolet/GMC truck/van lineup until the 4.3L replaced it. About all that can be done for a head with this intake, is the 1 barrel can be swapped for a 2 barrel by using an adapter. Integrated intake cylinder heads had one-barrel carburetors until the 1979 model year (the light trucks with the 250 used a Rochester Varajet 2 barrel from 1979-84 which is not performance oriented. Not the hot ticket. The lump port mods along with porting, larger valves, etc. can be done to ANY head, but without the ability to use a high performance intake, these mods would be largely wasted. |
| − | Using the earlier head (or one from a 1975-1990 tall deck 292) with the detachable intake from a 194, 230 or 250 | + | Using the earlier head (or one from a 1975-1990 tall deck 292) with the detachable intake from a 194, 230 or 250 c.i.d. inline Chevy 6 offers a much better platform. Because of the current lack of aftermarket support for inline Chevy 6 cylinder heads, the hot rodder is left with the removable intake head from the early/mid 70's as the best choice for performance use, unless the cost of a custom head can be justified. |
In the past there were heads made for the Chevy 6. Now there are one-off heads for the Chevy inline 6 that have been made from 2 SBC aftermarket aluminum heads that have been divided and welded back together. Another hybrid cylinder head is usually made from two Vortec 3.0 (181) used in marine or industrial applications - the 3.0 is based on the Chevrolet 153 engine first used in the 1962-67 Chevy II and some 1968-70 Novas (including the Chevrolet/GMC G-series vans (1964-66) and the Jeep DJ-5 (1968-70) used by the United States Postal Service). | In the past there were heads made for the Chevy 6. Now there are one-off heads for the Chevy inline 6 that have been made from 2 SBC aftermarket aluminum heads that have been divided and welded back together. Another hybrid cylinder head is usually made from two Vortec 3.0 (181) used in marine or industrial applications - the 3.0 is based on the Chevrolet 153 engine first used in the 1962-67 Chevy II and some 1968-70 Novas (including the Chevrolet/GMC G-series vans (1964-66) and the Jeep DJ-5 (1968-70) used by the United States Postal Service). | ||
| − | A relatively easy to find head to swap on the 250 inline Chevy is casting number 3864883 from a 194 | + | A relatively easy to find head to swap on the 250 inline Chevy is casting number 3864883 from a 194 c.i.d. Chevy inline 6 engine. If it's milled 0.060", it will give about 10:1 compression on a Chevy 250 using stock type pistons. |
===One-off custom aluminum head=== | ===One-off custom aluminum head=== | ||
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Just goes to show you what can be done with enough skill, tools, time and dedication. | Just goes to show you what can be done with enough skill, tools, time and dedication. | ||
| − | [ | + | [Kay Sissell] has also done some custom heads for the inline Chevy six. He now offers ported cast iron heads and other parts. |
===Intake port mods=== | ===Intake port mods=== | ||
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