I have had good results adding 10 gallons of 110 leaded Torco to the 87 unleaded tank in our equipment yard. The 361 2 barrel would ping on hot days with a full load in the D600. Even blackie the W100 shop truck with a 318 (summit cam) would also run poorly on the un-spiked 87. That surprised me. The 110 cured all of my problems including percolation in a hot shut down condition. 87 unleaded is irritating!