Olds Oil Flow/Oil Restrictors

this is a referrence to the oil flow and the use of oil restrictors courtesy of Art at www.arrace.com . i didn’t see any need to elaborate on it. it’s well written and worth sharing.

 In the first pic, oil is pulled up by the oil pump through the oil pickup.  The oil pump pushes the oil through a passage in the #5 main cap and then through a horizontal passage approx .500″ to the oil filter adapter.  The oil is routed to the outer passages in the oil filter and forced through the oil filter element to the inner passage in the oil filter then back into the oil filter adapter and then back into the block through the large .500″ horizontal passage that you can clearly see on the rear of the block.  The oil makes a 90* turn up and then makes a 90* turn into the passenger side oil gallery.  (Note: There is also a .312″ diameter passage that continues straight from the large passage and then make a 90* turn to feed the #5 cam bearing.)  The oil flows forward to the front of the block in the passenger side oil gallery feeding the 8 passenger side lifters, mains #5, #4 ,#3 & #2  and cam bearings #5, #4, #3 & #2 along the way.

Once the oil reaches the front of the block it make a 90* turn down toward the main bearing.  Once the oil reaches this point it diverges into three different directions.  The #1 Main bearing,  The #1 cam bearing, and up to the driver side oil gallery.  The oil makes a 90* turn into the driver side gallery which feeds the driver side lifters.  (Note: The # 2, #3 & #4 do not feed into the drivers side gallery.  [i]See 3rd pic.

Restrictors are typically installed as shown in the diagram below.  The main restrictors as they are called restrict the oil going to the cam bearing journals ONLY.  This increases the oil to all other areas.  The ONLY restriction is to the cam bearing themselves.  Properly sized restrictors in this location can be used in any engine without fear of any damage.  Street, street strip, drag, circle track, off road & boat.  The cam bearings do not need all that oil and you can clearly see that by limiting the flow of oil to the cam bearing that the only other place it can go is to the mains on #1, #2, #3 & #4 and to the drivers side oil gallery.

Lifter bore restrictors should only be used with solid lifter or roller cams a then only if you know what you are doing.  Restricting oil here will limit the flow of oil to the top end including the lifters and rocker arms.  Care should be taken here as going too small can cause damage.

Some builders block lifter passages on the passenger side completely and tap into the drivers side gallery and feed all lifters from the same gallery leaving the other gallery to feed only the mains and cam bearing.  My 414 Olds is this way.  Pauls engine also has this setup.

Blocking filter bypass.  Drill & tap oil filter adapter for a 1/4″ NPT plug after removing the oil bypass assembly.  This prevents the oil from bypassing the filter element.  If you do this I recommend a GOOD filter such as a Sytem 1 and clean it often.

Proper size restrictors are available from [url=http://www.oldsperformanceproducts.com/products.asp?page=3&menulevel=Oil%20System%20Components&submenu=]Olds Performance Products [/url]and they can supply you with a proper tap as well.

Comments are closed.