The Stovebolt Site Forums The Shop Area Engine Shop Please check out this picture - i.d. the ports?

Here is a photo of the side of my 261. I "thought" that I had it plumbed correctly, but now I'm not so sure.

http://www.flickr.com/photos/28944139@N04/2701604481

If anyone thinks they know the 261 pretty well, I'd sure appreciate a little knowledge being tossed my way. Please take a look at the photo and see if you can tell me what goes where.

I currently have oil coming out of port #3, going to the external oil filter and returning into port #4. Ports #1 and #2 are a mystery. Oil seems to come out of #3 and #4 when we crank the motor over. Nothing comes out of #1 or #2. I'm confused to say the least.

I'm not a 261 expert but I think that the pressure port is the rear one (#4) and the return port is the lower one (#3). The 235 is made that way with the return at the rear and at the pan level. Number 2 looks the correct size to be a petcock for draining the block of coolant. I don't know about #1. Are you sure it's an oil hole and not a bolt boss?
BUT..how do you propose to get your exhaust pipe on the manifold with that rear hose on there like that? Looks really close to me and it would be very hot at the least.

Someone here will know for sure after while. In the meantime do a search on oil filters as there is some excellent info posted just recently.

#1 is the oil bypass plug or pin.
It needs to be pushed IN for the oil to flow from the oil pump straight out to #3

It needs to be pulled OUT for the oil to bypass #3 and #4 which have to be plugged.

! Do not plug #3 and #4 if the plug is pushed IN !
It would stop any oil flow from the oil pump to the entire engine!

Hard to see from your picture, but it looks like the plug is pulled out.
If it's pushed in it will be recessed almost 3/4"

#2 is the remote bypass oil filter return, which was used on earlier 261s. This passage drains straight into the oil pan.
It should be plugged if no remote bypass filter is connected.
Later 261 blocks no longer had this passage drilled and tapped.

#3 is the outlet after the oil pump that goes to the full flow filter input.

#4 is the inlet for the return line after the filter.

About #1.

By pushed in, do you mean it just has to be threaded as far in as possible?

There is no thread.
It can be pushed in from the outside and pushed out from the inside.
I never had to mess with mine, as the plug was pushed in already and the original filter setup was connected.

Hmm, mine is a plug. Internal hex head. I've removed it and found nothing behind it. What you said makes some sense. On the other hand, I now have no place to hook up the oil pressure gauge. Do you know of any literature that talks about this. I've never seen this discussed before.

On my 1962 block I can see a plug that's pushed almost 3/4" inside. There are no threads visible.

Here is how I connected the oil filter with copper lines and flare fittings.
For the oil gauge, I drilled and tapped into the 90 elbow fitting that connects the oil filter return line back to the block.

Oil filter lines 1

Oil filter lines 2

Well, that IS kinda weird. Mine is threaded. I wonder if there is supposed to be something behind my little plug. What keeps your from falling out?

We'll probably do the same thing with tapping the fitting to get the O.P. for gauge.

If anyone out there knows about this "bypass plug", please fill us in. Thanks.


JIM

You mentioned that oil flows to the filter, so you should probably leave things as they were, unless the flow was not much.

Just make sure that the oil pump is not plugged !!
With oil flowing through the filter or bypassed.


The 1960 truck shop manual shows a picture of the full flow oil filter and connections.
However the block casting in the picture didn't even had this plug and no mention of it....?

On my 261 I made it a full flow filter system. The pin drives in about 3/4". It drives in hard--40 psi of oil pressure will not move this pin.

I got my oil pressure feed near the front of the engine. Between the generator and the block is a 1/8" pipe plug. I removed this plug and installed a 1/8" copper line that runs straight up and over the intake/exhaust manifold. I then used a 1/8" pipe coupler so I could adapt the OEM gauge line to the line I installed. I have been running this for two years and it works great.

Very clean setup, I like that and will probably go that way on my full-pressure 235.
Thanks for sharing.

My port where this plug is supposed to be is THREADED! Does any one else have a threaded port here? This is becoming a major concern, not to mention a pain in the @#$%.

Thanks,

JIM

Maybe the diverter plug/pin started to leak or was removed at some point and the previous owner tapped the hole and plugged it.

As long as all of the oil flows to the filter that would be acceptable and nothing to worry about.