PCV restrictor diameter
Posted: Fri May 30, 2025 10:43 pm
Found this on a tuning forum:
Re: Negative Crankcase Pressure
10 years ago by pixelsmithusa
San Francisco, USA USA
The large port connection on the manifold will be too much if not used with the original Smiths PCV. How this is all plumbed also depends on which carbs you are using. If you are setting up you own vacuum source from the manifold, it should be regulated by a 9/64" diameter hole. One of these arrangements will work, but most likely only successful if your rear main is assembled correctly and has the right factory tolerances. Keep in mind that once the engine is shut off, there is nothing to prevent accumulated oil from leaking at that point. That is additional benefit to the design of my rear seal kit.
9/64ths seems very precise...anyone come across alternative values? The valve cover filler cap breather diameter is I think 5/32 which is pretty similar...
Re: Negative Crankcase Pressure
10 years ago by pixelsmithusa
San Francisco, USA USA
The large port connection on the manifold will be too much if not used with the original Smiths PCV. How this is all plumbed also depends on which carbs you are using. If you are setting up you own vacuum source from the manifold, it should be regulated by a 9/64" diameter hole. One of these arrangements will work, but most likely only successful if your rear main is assembled correctly and has the right factory tolerances. Keep in mind that once the engine is shut off, there is nothing to prevent accumulated oil from leaking at that point. That is additional benefit to the design of my rear seal kit.
9/64ths seems very precise...anyone come across alternative values? The valve cover filler cap breather diameter is I think 5/32 which is pretty similar...