My old 87 f150 w/4.9L is starting to exhibit some blowby. The breather gets blown out of the valve cover (it fits in tightly) and I get a small amount of oil in the breather filter. The engine consumes very little oil, about a half quart every 2500 miles. PCV system is working but I would like to try a "high flow" PCV valve. Does anyone have a OEM or Fram number I can go from that might work?
Try a dual stage, adjustable PCV valve made by ME Wagner http://mewagner.com/
The last PCV valve you will need to buy.
A fixed orifice PCV valve will not work well at higher speeds and loads due to low intake vacuum. That is when you need crankcase ventilation the most when blow-by is greatest.