Is some engine weapage normal? I might have a spot the size of a half dollar or less on two engines. Seems it coming from the rear seals on both of them. Not sure it’s worth the expense to to get a perfectly dry engine.
For the first 60 years engines used cork and rope for sealing and weepage was normal. After neoprene and other synthetic materials came into use there was no longer migration of fluids through the material itself but the biggest contributor to leak free engines has been with pressure control. The number one step came with the PCV system but much closer tolerances on rings, pistons, valve guides, and anywhere else there is a path for fluid to move from internal to external has been minimized. This along with advances in gasket material, sealants, and close tolerance fitment have made for clean engines. Many new engines call for 5-20 or even 5-10 oil. 30 weight oil will destroy one in a very short time. Can you imagine 5wt synthetic oil in an old Stovebolt; the oil would go from filler tube to garage floor in one motion.
RE : Weepd & Seeps of oil : Yes, some dripping at the rear main seal is normal . I've heard good things about the new neoprene seal designed to replace the old rope typ seal, I have never used one . The PCV valve is easy to install and really helps reduce leaking / seeping / weeping plus it keeps your engine cleaner inside so it lasts longer, much longer . Clean your engine well and run it, look for weeps around the side cover plates and rocker box, use a cork typ gasket glued to the sheet metal cover or simply glue the gasket on both sides with Permatex' "THE RIGHT STUFF" from an aerosol tube . Gluing the rocker box on means you'll have the devil of a time getting it back off to do your routine valve adjustments though..... DO NOT waste time using regular RTV sealants ! . There's supposed to be a flat round gasket at the base of the distributor too .
I just put a stock (for larger trucks) PCV valve in my '52 GMC 228" six cylinder. Noticed two things. First, I had slight blow-by before installing the PCV system. Not bad. The engine dripped and blew out the vents maybe a quart every 600 miles or so. The PCV system has gobbled up the blow-by. And maybe it is my imagination, but I think it is dripping less on the ground. I've driven 350+ miles and the dipstick has stayed on full. Second, my gas mileage has increased from a very consistent 15.5 to 16.2 MPG without the PCV system to a very consistent 16.7 to 17.4 MPG with the PCV system. At first this sounded good. Then I started wondering "why"? I pulled the spark plugs and noticed that they seemed a bit lean. While better gas mileage saves me money, burned valves will cost me a lot more. I changed the jet in my carb two steps bigger (0.099" to 0.104") , hoping to fatten the mixture. Gas mileage stayed in the low 17 range. I just took the jet two more steps (to 0.110") and I will road test it tomorrow 200 miles round trip to Austin. Carb is a Carter YF.
Keep a sharp eye on the plug insulators, they're supposed to run cleaner than the shop manual pictures show because of the modern lead free fuels . As long as the engine doesn't over heat nor ping (full throttle ping test in third gear) lite coloration on the insulators is a very good thing . Remember : the closer to 212* F your engine runs the more power it will make and run cleaner and last longer too . The trick is ensuring the cooling system is up to the job and properly maintained .
Nate gave away one of my secrets on power and economy---higher temps. All my street rods have welded aluminum radiators and Vintage or Old Air heater cores. I run a 16# cap which raises the BP to 260* which lets me run at the desired 238*. My wife's Buick had dual electric fans where the first one comes on at 238* and the second one at 254*; same as a Corvette. Running the billet aluminum engines (no water jacket in head or block) for the pull truck on the dyno showed they reached maximum power at ELEVEN minutes of running time. After reaching the max the power dropped off RAPIDLY. The ideal set up was to hook to the pull sled after 6-8 minutes of heat build up.
