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   Emissions and Crankcase Ventilation 
    Breather System Design #1
             Initial problems and ancillary system modifications

   Emissions and Cranckcase Ventilation Issues

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


    OK I need/want a lower crankcase breather. But were do you come up with a crankcase vent port.  Bummer... Oh well, looks like I'll have to install an electric fuel pump. That way I can pull off the mechanical pump on the side of the block.
gt6electricfuelpump.jpg (29332 bytes)   

   Well I'd be hard pressed to believe this is NOT.. where Triumph would have mounted the pump if they had stayed with an electric unit. You're looking at the left side frame rail from the rear, from just under and inside the left rear wheel.

   I installed a generic 1307 SU fuel pump as they are rated at a nice 2.5-4 psi and have proved rather reliable in my other LBC's. It tucks up underneath rather cleanly. I've considered a rock guard, but haven't needed it yet.


   To mount he pump I simply welded the heads of two meaty bolts to the side of the frame. I bent myself an 'omega' shaped pump mount bracket and bolted it up tight under the body work on the side of the frame rail. I added a fuel filter here, ahead of the pump, as well as a 1/4 turn fuel shutoff valve (orange handle). This will make it easy to change the fuel filter without the tank emptying all over me.  So with the pump out of the way, I can go about, designing a breather box.

   Breather design goals...

    OK.... the breather box needs to allow the air in the crankcase to escape, without pushing oil out. It must also act as a port for returning oil to the crank that might have collected in the breather air/oil separator box(es).

   I'm cheap. When I experiment, I hate to buy materials.   So I try to build stuff out of what I have at hand.  So naturally this first unit was built out of a Spitfire gas/air separator. I welded a Chevrolet aftermarket blanking plate to the side via  short piece of threaded pipe. The Chevy plate needs to be cut down a bit, but fits the bolt pattern of the old fuel pump studs.

   I was hoping to 'T' the crankcase port and the rocker cover vents together to allow for freer breathing. But it quickly became obvious, the ports were too small to really pass any volume. Pressure still built up rather quickly. So this model was scraped with minimal testing ever performed.  



breathermodel1.jpg (15628 bytes)

   Emissions and Cranckcase Ventilation Issues

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