I added an optional stock GMC PCV valve using stock fittings and PCV type valve cover (no vents) to my '52 228. I cut the draft tube off the oil filler tube and plugged the hole. Then I used a 3" piece of rubber hose zip-tied to a Mr. Gasket oil filler/breather to sit in the top of the oil filler tube as a source of incoming air. Worked well until I realized my average gas mileage had increased from around 15 MPG to 16.5. (Carb is a Carter YF). I pulled some spark plugs and sure enough, they were looking lean. A PCV system is just a controlled vacuum leak after all.
In an attempt to fix the lean problem before it got too serious I temporarily installed an AFR gauge and tried various jets in the YF. Never could get to where I wanted to be so ....
I removed the stock PVC valve from the intake manifold and installed an small oil separator from an air compressor between the fitting in the top of the valve cover and a tube that I welded to the side of the air cleaner. Fresh air source remains the Mr. Gasket breather. About once every 5 tanks of gas I drain about 5 cc of oil from the oil separator. I'm back to the original 0.099" jet in the Carter YF. Gas mileage is where it was before the experiment started and plugs look good.
Last edited by Bill Hanlon; 04/16/202212:04 PM.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
