i have a 225slantsix race car,with 4-71 blower. i am trying to make a distributor that will leave the line at full advance then when boost comes on retard timing by 5degs, i have put together the mechanical adv parts from 225dist the gives me 25degs total timing at 2500rpms and i then installed the pickup coil and plate with vac canister from a 440bb and hooked it to port vac at the carbs. it is working but the vac side is pulling out to much timing and at to low rpms, idle 1200 rpms 10degs/ 2500rpms 25degs/3000rpms 20lbs vac 10degs,is there anyway i can reduce vac at port fitting on carb or delay it for higher rpms,i have tried screwing the adjuster nut in the vac canister it help a little but i need more delay.any help would be appreciated