Some engines of that era had chamfered top lands to reduce the crevice volume above the rings, which can account for up to 25% of the total hydrocarbon emissions. It did have a negative affect on other aspects of the burn quality though.

Last edited by THE FRENCHTOWN FLYER; 09/06/17 03:29 PM.
FORD 300 inline six - THE BEST KEPT SECRET IN DRAG RACING!