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567chevys
07-15-2011, 11:56 AM
Please note that B/S ratio refers to the bore-to-stroke ratio. And is used to factor in whether or not an engine is square. If the bore and stroke are equal,then the engine is square. If an engine is over square then the burn rate in the chamber is too slow. Smaller cylinders decrease the burn path making it burn faster. But,restricts the size of the valves thereby restricting horsepower potential.

For engine builders,it's more effective to think in terms of rod-stroke ratio. For example,a rod-stroke ratio of 1.75-1 is ideal for an acceleration engine. The 327 Chevy had a 1.72-1 rod-stroke ratio. That's one of the reasons the 375 hp 327 beat a 375 hp 396 in the same cars down the quarter mile.



Disp. Bore Stroke B/S Ratio Years Produced
265 ci 3.67 in 3.10 in 1.18 1975
265 ci 3.75 in 3.00 in 1.25 1955-56
267 ci 3.50 in 3.48 in 1.03 1979-82
283 ci 3.87 in 3.00 in 1.29 1957-67
302 ci
4.00 in 3.00 in 1.33 1967-69
305 ci 3.75 in 3.48 in 1.08 1976-97
307 ci 3.87 in 3.25 in 1.19 1968-73
327 ci 4.00 in 3.25 in 1.23 1962-69
350 ci 4.00 in 3.48 in 1.15 1967-97
400 ci 4.12 in 3.75 in 1.10 1970-76

These production numbers are in reference to the engine manufacturing. Some engines were installed in cars & trucks for a couple years after their respective production dates due to excessive inventories.

Disp. Main Journal Rod Journal Main Cap
262 ci 2.45 in 2.10 in 2 bolt
265 ci 2.30 in 2.00 in 2 bolt
267 ci 2.45 in 2.10 in 2 bolt
283 ci 2.30 in 2.00 in 2 bolt
302 ci,67 2.30 in 2.00 in 2 bolt
302 ci 68,69 2.45 in 2.10 in 4 bolt
305 ci 2.45 in 2.10 in 2 bolt
307 ci 2.45 in 2.10 in 2 bolt
327 ci 62-67 2.30 in 2.00 in 2 bolt
327 ci 68,69 2.45 in 2.10 in 2 bolt
350 ci 2.45 in 2.10 in 2 & 4 bolt
400 ci 70-72 2.65 in 2.10 in 4 bolt
400 ci 73-76 2.65 in 2.10 in 2 bolt