The Stearns Knight eight cylinder engine was 385 cubic inches making it the largest straight eight cylinder engine available in the US until Duesenberg came along in 1929. As a sleeve valve engine it has double sleeves, one for intake and one for exhaust with 3 crankshafts.  One crank was for the pistons, and the other two were for the sleeves.   The engines were under constant engineering update during production and you will see a number of different features between early and late cars.
If you are interested in these cars check out the Stearns Eight Cylinder Society. Open to anyone interested!
https://app.rumbleseat.com/club/1/Stearns-Knight-Eight-Cylinder-Society