BogusSVO
Well-known member
4G63 Block Vent
I have read a few threads on adding a block vent to the 4g63.
I know this not a new idea, and others have had done it before.
I also know that there is a kit so a block vent can be added in at the rear balance shaft timing passage.
Some of the locations I have seen used I did not like, or the size of the fitting being too small to be very effective.
After spending some time looking a block over, and looking at an assembled engine. I believe I found one of the better spots to install a block vent.
Since there is a factory vent from block to head, tapping into this spot makes the most sense to me. It is on the down side rotation of the crank, and is decently covered and high enough in the block not having to worry about oil slosh or oil return from the head. Also this should pull from the head as well as the block.
Also looking at an assembled engine, this vent looks to clear the starter and the intake support bracket.
I chose to use a 1/2npt 45* fitting with a 5/8 hose barb. This should give plenty of cross section and make an effective vent. The ID of the fitting is .530 The reason for a 45* instead of a 90* is so there will be less of a flow restriction through the fitting.
I scribed a simple circle for the location, then did a center punch dot
It is a basic drill and tap install.
For a ½ npt the drill size used is 23/32
Then tap a few thread, care needs to be used since this is a thin cast area.
Test fit the vent fitting and tap until the proper angle for the hose fittings face the desired angle.
Try not to extend the threaded portion of the fitting into the factory vent passage.
I have read a few threads on adding a block vent to the 4g63.
I know this not a new idea, and others have had done it before.
I also know that there is a kit so a block vent can be added in at the rear balance shaft timing passage.
Some of the locations I have seen used I did not like, or the size of the fitting being too small to be very effective.
After spending some time looking a block over, and looking at an assembled engine. I believe I found one of the better spots to install a block vent.
Since there is a factory vent from block to head, tapping into this spot makes the most sense to me. It is on the down side rotation of the crank, and is decently covered and high enough in the block not having to worry about oil slosh or oil return from the head. Also this should pull from the head as well as the block.
Also looking at an assembled engine, this vent looks to clear the starter and the intake support bracket.
I chose to use a 1/2npt 45* fitting with a 5/8 hose barb. This should give plenty of cross section and make an effective vent. The ID of the fitting is .530 The reason for a 45* instead of a 90* is so there will be less of a flow restriction through the fitting.
I scribed a simple circle for the location, then did a center punch dot
It is a basic drill and tap install.
For a ½ npt the drill size used is 23/32
Then tap a few thread, care needs to be used since this is a thin cast area.
Test fit the vent fitting and tap until the proper angle for the hose fittings face the desired angle.
Try not to extend the threaded portion of the fitting into the factory vent passage.
