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   Emissions and Crankcase Ventilation 
         Research - A study and a fix.. for a Triumph GT6

   Emissions and Cranckcase Ventilation Issues

Home   Research and decision making    Standards and calculations    Exhaust scavenging     D-I-Y   

    I'm could leave it right here with this link. Read this PDF file! It'll open in a new window, then save it locally so you can read it your leisure, AND over and over again.  Although written for boaters, the problems and solutions apply to any environmentally friendly engine.

   The information concerning 'expected blow-by' based on engine size is quite surprising, but as I've now found, very realistic!

lilgreenbreather.jpg (36343 bytes)
1973 MG 1275cc A-Series Engine

    I started looking at my other 'leak-less' LBC's to see why they didn't blow oil and how/if they were ventilated.  On my MG 1275cc A-Series Midget engine, the carb side breather ports are routed to an oil/air separator mounted on the front of the timing chain cover. The oil filler cap is vented.  On some model years, the rocker cover has a vent pipe (with flow limiting orifice) that goes to the top of the carbon canister.  This is the way my MG B-Series engine is setup in my '73 MG BGT. On those installations,  the filler cap is not vented.

   I had to figure out just where, why and how much, pressure was being built up and when (rpm and load condition) . I replaced the upper breather pipe with a spare piece of hose with a   vacuum / pressure test gauge T'ed into it.

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Late model 1973 MKIII GT6 - stock breather configuration 'as delivered'

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Late model 1973 MKIII GT6 - stock mechanical fuel pump still in place

    One early set of tests performed was applying full manifold vacuum to the lower crankcase. In this shot you can see my Mity-Vac brake bleeder bottle being used as an oil catch can. The blue line is a vacuum gauge, T'ed in, just before the vacuum line enters the oil dipstick tube.  What was I trying to accomplish here? Heaven knows.!  I think I was listening for air sucking in past the oil seals on the timing cover and under the rear of the oil pan or something like that....

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