Bypass oil system return

[ToddT]

A few months ago I asked about adding a "real" oil filter to my Changfa copy engines. Y'all told me about splicing into the oil line that feeds the head. Sounds simple enough... but where do I return the oil after it goes through the filter? One member said to drill and tap a port but where do you suggest adding it?

Also, I don't want to starve the head for oil. Should I add a metering valve to restrict the flow to the filter so as to keep most of it going to the head?

By the way, I'm going to start a sound-deadening project soon. I'll keep y'all posted.

Todd

[vdubnut62]

I'm not an expert by any means, but I plan to splice into the line to the head, run it through an old (1940's vintage Chrysler) cartridge filter, then plumb back into the line,
and return that to the head. The filter has a line in at the top, and a line out at the bottom.  Both, I think, are 1/8 pipe thread. 
That's just my plan, for what it's worth.
Ron

[mobile_bob]

the oem oil line feeds the pressure indicator in the valve cover, it basically doubles as a pressure regulator in that it is spring loaded
and when the pressure is high enough it lifts the piston and opens  a dump port back into the valve cover.

bear in mind the pressure when cold can be very high, reports of 150-300lbs are not uncommon, although it drops off to more realistic
pressures when hot it is still rather high at over 80psi supposedly.

if you want to go to the trouble to do it right, you will have to tear down the engine, the ports are available but plug welded and will have to be
redrilled to gain access. the port is under the end housing under the starter.  you will have to drill out the plug, insert a plug iirc to the main galley and then take the accessed oil supply, filter it, regulate it to realistic levels and reintroduce it into the port in the timing cover which will then feed the mains and rod again.

some of the higher end changfa's have real oil filters, the housing fits against the rear crankcase cover and the cover has the oil pressure regulator cast and machined into it.

in an effort to lower costs on these engine's they deleted the oil filter, oil pressure regulator, and plugged the galleys so that they could go directly from the pump to the mains.  it works i guess but the result side effect is very high oil pressure and no filtration.

also of note, i can't believe that running at very high pressures is good for the oil pump or its little slot drive, my bet is reworking for filtration and a real regulator with the pressure limited to perhaps 45psi hot, which probably would be about 60psi cold would result in a much longer lived engine.

one other thing, while you have it apart, replace the cheap counterbalance shaft brgs with something made in a first world country, the chinese brgs have some issues in some engine's. seems like cheap insurance to upgrade these heavily loaded brgs while you have it apart.

bob g