The knob in the pic is the grease cup. The slotted hole with the hash marks is the octane selector. It screws to the dist pad. You can fine tune from 0 deg to 10 deg advanced or retarded and return to the original setting anytime. Hope this picture comes through!
~~ Jethro 1954 3100 Back to Life In the Dity Gallery 1951 3100 (gone) / 1956 4400 (still in the neighborhood) / 1957 6400 with dump body (retired) / 1959 3100 panel (in the woods junked) / 1978 Custom Deluxe K10 / 1993 S-10 4.3 / 2004 Chevy Crew Cab / 1945 John Deere H / 1952 John Deere B / 1966 John Deere 2510 / 1967 John Deere 1020
