the hobbs switch with a set amount of timing pullout will work fine. but if you get the boost up near 10, you may need better timing control.
on the fuel issues, could you be running it too rich? AFR around 10 is for a engine under alot of boost. i only run mine down to 11.25 around 10-15 lbs boost and higher rpm, 4500. maybe you are just flooding it out. on mine a sure sign of a lean was a sort of stuttering under load and finally a BIG backfire if i stayed into it. i would guess at 3 lbs a AFR of 12 would be ok. my cruise AFR is 12.75-13. idle is 13. i can't really go leaner or it runs bad. tom
