Whoops, there's a typo in my 41 custom pilot jet message above; the custom 41 was made from a Keyster 40, not from a 42.
3&1/3 turns out on the pilot screws proved to be slightly too rich, & 3.25 was slightly too lean for what I want. The pilot screws are now just over 3.25 turns out and the cruise AFR is about where I want it. Just gotta make sure there is no carb spitting. At 3.25 turns out on a fully warmed up motor the idle AFR was hovering about 14, and that's lean enough at idle to induce carb spitting with the hotter 813 cams. At 3.34 turns out (I can't really get that precise, but I like saying that better than 3&1/3) the idle AFR was in the low 13's with no carb spitting, but the cruise was still a bit richer than optimal. Just goes to show you what a small sweet spot there is when the needle, pilot jet, pilot mixture screw, float height, and throttle plate bleed hole diameter work & play well together.
WOT high RPM is a bit leaner than I want, so up next will be a set of custom main jets; it has a set of 152.5 aftermarket jets in it now; I believe that the aftermarket jets are marked true to the actual bore size. Keihin main jets are not true to actual bore size (with Keihin mains, the actual bore size is generally smaller than the number marked on the jet).
Anyway, I made a set of "153" main jets (with a 4-flute #53 wire gauge reamer) using a set of Keihin 152's as donors. FWIW, the #53 reamer wont pass through a set of Keihin 155's (just every so slightly too tight) but pass clean right through Keihin 158's). If for whatever reason the "153's" prove to be too large, then I can always drop back to Keihin 155's.
Just gotta get some time to install the modded mains & some daylight dry weather so I can test 'em.
If my theory is right, and presuming that the larger mains do what I expect them to do at high RPM WOT, then the pilot mixture screws may be able to be leaned out slightly more...
I also want to try my 2.8mm transfer port vacuum pistons (slides) again...but after the main jet experiment.
