The Stovebolt Site Forums The Shop Area Engine Shop 54 261 drilling for full flow oil & casting # ?

I was about to drill my 261 block for a full flow oil set up and I have a question.

In step 2 here

I'm trying to figure out if this is just a return line to the pan or if I am drilling and tapping into a passage. It looks to me like its just a return line. If that's the case why does it have to be in that specific location? seems like it could be anywhere as long as it dumps into the pan...

Since this is an early 261 I know I need to restrict the oil flow a little... I'm not sure why exactly and how much restriction (psi) I'm Looking at so shed some light here for me.. I'm in the dark...

2) casting numbers (3733950) say this block is a 54-56 261 but the casting date code(K197) says it was made in November of 57? does that make sense?

Thanks folks!

Jeremy

Jeremy this site shows your 261 as being from 54-57... Some of the others only list it as 54-55...

I heard from a usually reliable source those engines were built as replacement engines for several years after the last one left the factory in a '55.1 truck. That accounts for the later casting date.

Well, I'd heard they seasoned the blocks but wasn't sure how long they sat.
It still amazes me that you could cast something 50 years ago that is that big and intricate and expect it to:
1- withstand heat and pressure for extended periods of time
2- maintain some level of tolerances so that it could be precisely machined
3- barring the above makes a he'll of an anchor!

Jeremy

So does the casting date affect your original question? Is there something about an early block that prevents the conversion?

Which type of water pump passage does it have?

The whole reason for doing this modification is to convert the engine from "bypass" filtering to full oil flow, where all the oil going to the bearings is filtered before getting from the oil pump to the engine. That's why the first operation described involves plugging the original oil passageway. The second hole, the one that's drilled and tapped from scratch, is where the oil goes that's supplying the main bearings, so yes, its location is critical. You're taking all the oil pump output, and routing it through the filter, then putting it back into the block to supply oil to the bearings. NO restriction is needed, and a filter capable of carrying the full output of the oil pump without dropping pressure excessively will need to be used. The original bypass type filter WILL NOT work after the modification is made- - - -you'll need to fit an aftermarket remote filter mount set up for a spin-on filter. I prefer to use an adapter with a bypass valve built in, in case the filter gets clogged enough to start affecting oil pressure. Most bypass valves work anytime there's a 5-7 PSI drop across the filter media, routing oil past the filter anytime it gets clogged. The third hole that's described in the tech tip is the new connection point for the oil pressure gauge line, downstream of the filter.

Later-model 261 engines, the ones with the 1/2" NPT oil line ports, are set up for full-flow filtering from the factory, and MUST be used with this type of filter, or a 1/2" flex line needs to be connected between the ports to prevent the bearings from being starved for oil if the filter is not used.

Follow the tech tip instructions to the letter- - - -they're all there for a reason!
Jerry

Jerry-
Thanks, I missed the part where the hole is drilled into the oil pump passage.
When I made the notes on the block I had the block upside down on the head surface. I made the mark on the wrong side of the oil drain for the bypass filter.
When I "flipped" the block onto it's pan surface, I looked at the photos and realized I'd mis marked the drill spot.
That's how I got confused since I couldn't see the oil pump outlet any more....

It may seem obvious now, but i'm certain it's not as clear as all of the folks who have been around these motors for years think.

Thanks again,

Jeremy

It has the high water pump with the two large holes.
No, nothing about the date of the block keeps me from doing the conversion.
I wa just concerned about the oil being able to to bypass the filter if something happened.
HRL explained it so now I can drill everything and drop it off to be bored this evening.

Wow... Maybe I can get my engine together this weekend!

Thanks, all

Jeremy

I have really pondered this modification also. My 54 235 originally came ith no filter at all so I was real proud of myself when I "stepped up" and added the Fram style bypass filter. I have been told that these engines were designed to be work horses and it was common practice to overhaul them "in the field by installing new rings and bearings with no reat attention paid to the environment. Of course, life expectancy was less back then also as was the metal technology standards.

So I don't know whether to drill my 54 261 block and try to figure out what to do with the remote oil filter, or to just keep my same old bypass filter and plan on more frequent oil changes. In my days of stupid youth, I must have had money to burn and certainly more than brains because it was common practice to change oil every weekend. What a maroon huh?

I'd suggest running both styles of filter, like the big Cummins and Detroit engines do. There's a full-flow filter to strain out the big stuff such as rocks, marbles, and railroad ties, and the bypass filter has a much finer-mesh filter element and strains the tiny particles out that the full flow filter can't trap due to the volume of oil through it. The bypass filter has a restrictor that slows down the flow and dumps the oil right back into the pan, without having to flow enough oil to keep the bearings lubricated. The Frantz-type filter that uses a roll of toilet paper for a filter element is a perfect example of a bypass filter that traps even microscopic particles of dirt.
Jerry

Thanks for the explanation. Now I have more understanding and it will come in handy if I ever use one of these 261s.

On a note about engine life: I picked up some old Popular Mechaincs magazines at a flea market and one is from 1955. One of the articles has hints on how to take special care of the engine so that you can get the expected 50,000 miles and even beyond out of it before it starts to burn more than 1 quart in 200 miles!!