According to hondalogger, my duty cycle on 440's is getting close to 60-70% running at .5 bar and 38 psi fuel pressure (measured with vaccum line disconnected). What's a safe base fuel pressure to run at for when I up to boost a little more? I've got a walbro fuel pump, aem fuel rail, 1:1 rising rate FPR, rc 440's.

 

just as a baseline, i always run 45 psi with the line connected, and you still will be safe on those 440s up to about 85% duty cycle.