Large rpm drop
Hook the vac gage to one of the low ports on the carb base*.
Either use a PCV or a fixed orifice.
From Chilton's General Manual 1970.
Fixed orifice sizes to substitute for PCV Valve Testing at idle:
Engine (cid) Hole dia. (in) fractional drill
90 to 140; 0.056 - 0.075 or 1/16
141 to 200; 0.074 - 0.088 or 5/64
201 to 275; 0.087 - 0.099 or 3/32
276 to 350; 0.098 - 0.112 or 7/64
351 and up; 0.111 - 0.125 or 1/8
Notice the equivalent PCV fixed orifice is about the same size as drilling holes to let more air in.
*
*
Bingo! That's critical!
Hook the vac gage to one of the low ports on the carb base*.
Either use a PCV or a fixed orifice.
From Chilton's General Manual 1970.
Fixed orifice sizes to substitute for PCV Valve Testing at idle:
Engine (cid) Hole dia. (in) fractional drill
90 to 140; 0.056 - 0.075 or 1/16
141 to 200; 0.074 - 0.088 or 5/64
201 to 275; 0.087 - 0.099 or 3/32
276 to 350; 0.098 - 0.112 or 7/64
351 and up; 0.111 - 0.125 or 1/8
Notice the equivalent PCV fixed orifice is about the same size as drilling holes to let more air in.
*
*