Crankcase Ventilation
Posted: Sat Apr 15, 2023 2:40 am
I have a 4.6 with older 3.5 manifold and 175CD carbs. I need to set up a crankcase ventilation system. Note the vehicle also has LPG so input air cannot be taken from between the LPG carb and the engine die to LPG fuel air mix being sucked into the crankcase with the resulting explosion risk in the engine.
The old 3.5 has a hole at the rear of the block with a air filter on it that allows fresh air to be sucked into the crankcase. At the top of each rocker cover is a pipe with a flame resistor that goes the base of each carb where the crankcase fumes are sucked into the engine.
Now the 4.6 does not have the hole in the rear of the block so I have to rig up an alternate crankcase ventilation system. I am thinking of simply putting a filter on the passenger side rocker cover pipe (or running an intake pipe from the airfilter upstream of the LPG system) and sucking the air and fumes out the drivers side rocker cover pipe through a flame arrestor to a branched pipe to the relevant port on each carb. This will mean that fresh air is sucked in via the passenger rocker cover, down into the crankcase, up into the drivers rocker cover and into the carbs, so achieving crankcase ventilation - this is similar to what happens in a Thor system.
Can I have your thoughts on this or maybe better suggestions though not interested in making modifications to the engine etc.
Thanks
Garry
The old 3.5 has a hole at the rear of the block with a air filter on it that allows fresh air to be sucked into the crankcase. At the top of each rocker cover is a pipe with a flame resistor that goes the base of each carb where the crankcase fumes are sucked into the engine.
Now the 4.6 does not have the hole in the rear of the block so I have to rig up an alternate crankcase ventilation system. I am thinking of simply putting a filter on the passenger side rocker cover pipe (or running an intake pipe from the airfilter upstream of the LPG system) and sucking the air and fumes out the drivers side rocker cover pipe through a flame arrestor to a branched pipe to the relevant port on each carb. This will mean that fresh air is sucked in via the passenger rocker cover, down into the crankcase, up into the drivers rocker cover and into the carbs, so achieving crankcase ventilation - this is similar to what happens in a Thor system.
Can I have your thoughts on this or maybe better suggestions though not interested in making modifications to the engine etc.
Thanks
Garry