The Stovebolt Site Forums The Shop Area Engine Shop 1961 261 ENGINE QUESTIONS

WHATS THE DIFFERENCE BETWEEN A 235 AND 261 WATER OUTLET ? 261 IS BIGGER ? AND ON THE 261 FULL FLOW OIL FILTER WHAT TYPE OF FILTER DOES IT TAKE ? I DECIDED TO USE THE FULL FLOW OIL FILTER . LAST I WANT TO PAINT MY ENIGNE THE RIGHT COLOR FOR 54, IS THE COLOR BLUE OR GRAY ?

What part are you asking about exactly? The thermostat housings are interchangeable.

As for the oil filter element. I would suggest taking the old element and filter housing to the local auto parts store and find a good fit.

Finally the color. I do not know for sure about the first 261's but later they were thier own color. They were green or yellow. Yes yellow..

The complete thermostat housings are interchangeable but in some cases you will need matching tops/bottoms because individual parts are not always mix-matchable.

Yes, the diameters of the radiator hoses are not the same. That is why some people use the 235 thermostat housing (that reason, and the fact that an original-style of some 261 thermostats are not very easy to find).

You will have to figure out how to make the lower hose work (if you have an original 261 water pump). I have cut a short piece off a 235 lower hose and put it inside a 261 wider hose at the radiator end (that "bushing" produced a good seal for many years).

In 1954, the 261 color was green, Alpine Green is a very good match.

If no one posts a part number for the full-flow filter cartridge, I'll post a number this afternoon/evening.

I've recently been through this myself and learned a lot. The 261 is very different than the 235 when it comes to the thermostat and housing. The 261 has a dual acting thermostat that allows some circulation through the engine during warm up that avoids hot spots until the main portion of the T stat opens. A useful feature I decided to retain although many go with the simpler 235 set up. The 261 will be tapped for a hose barb in the upper and lower potion of the T-stat housing and an original 261 water pump will have two outlets to feed the system although as I have learned a single outlet pump will work if you tee the line. If you decide to go with the original system I have the part # and make of the dual acting thermostat that I was able to get at NAPA.

Mind posting that NAPA # for the theromostat?

1958-63 261 full-flow oil filter for original canister: NAPA 1143 (and maybe: Hastings P21 107)

There are references here, but I think the color is yellow for 54-57 engines and green for 58-62 engines. The 58-62 MAY be full flow oil system, depending on the position of the dowel pin just above the lower oil port in the block. If the pin is pushed into the bloch, it is full flow. If the pin is flush, it is a by-pass system. Mine is an April '63 block (D3 3), but has a by-pass iol system. Propbably because it was a replacement engine in a '55 school bus.

Joe D.

261 engine colors

Greg Hill has some interesting information on replacement 261 engines. There might have been a few differences in replacement engines: differences with respect to what features/parts they had/used: parts used in the year of manufacture of the replacement block vs parts used in the year of the recipient truck. These would be things like type of oil filter and type of water pump. It looks like GM might have put recipient-year parts on the engine (water pump and oil filter and ??).

Joe D.

Does your engine have 1/2" NPT holes in the block for oil lines or does it 1/8" NPT holes in the block for oil lines?

Here are the numbers off the NAPA box for the thermostat: R943695 It also has the number 155 on it. It is a 180 degree unit and also comes with the rubber ring and steel sleeve to locate it in the housing.

Hope this helps!


-Mike-

Tim,
Where can I find Greg Hill's info?

Tc do you have a picture of a 261 painted green

it looks good but i think im going to go with gray or blue

I also like the gray better than the green. I also like the yellow. Blue is for car engines.

Tim

It has the 1/2 NPT taps at both locations. The lower is plugged and the aft is set up for a pressure gage. The distributor pad is blank. The head cast date is E221 and the block is D3 3. Pica if the oil taps:

http://s858.photobucket.com/albums/ab147/jdaniel171/?action=view&current=PC210055.jpg

http://s858.photobucket.com/albums/ab147/jdaniel171/?action=view&current=PC210057.jpg

Joe D.

Funny, I was going to paint mine yellow.
It was the color of my block originally, and even the bell housing was yellow.
When I bought paint, it was way too lemon colored.
I prefer light colors for mechanical components that way I can see leaks when they start and put an end to them early on..

Finally I. Decided to paint the block with professional rust oleum stainless steel. I like the bare metal look and the paint is tough.

Jeremy

Tim...
Isn't your pushrods cover inside out?
I like that someone pienned a dome I it to clear the oilpipe.
My cover was all sorts of twisted mess and I decided I couldn't get
it straight enough to keep oil leaks from happening so I made one from aluminum.
Then I installed the oil pipe....
They cut a hole in my new aluminum cover and had a dome welded into it...
DOH!

Jeremy

anyone on here ever used the 261 full flow oil filter ? or have pictures of the filter on their truck ?

That side cover is the original 1960 261 side cover. That "dome" is original.

261 with full-flow oil filter

I used one for many years. It is now off because it could not be mounted anywhere on the Fenton dual-carb intake manifold.

Will the filter work on the front of the intake manifold ? if it wont work on the front will it hit the 3 speed on the column linkages ? heres my filter
http://s20.photobucket.com/albums/b212/espinoza720/?action=view&current=IMG_20120323_211551.jpg

Big Dan,

I do not have pictures of the full-flow filter on the 261 installed in my otherwise standard 3-speed 1/2 ton 1954 truck. I took it off in 1995.

However, it was installed on the original manifold assembly and I think it was on the radiator side of the intake manifold.

While my filter is mounted on the half of the manifold that will be closest to the fire wall I have seen pictures of 261's with them on the intake portion of the manifold closest to the radiator. When I install mine in my 45 1 1/2 ton I may not have the clearance with the firewall and steering column and I will end up moving it forward but suspect I'll have to get new lines made.

I had new lines made when I move it to the forward location. If I ever put the filter back on, I will use metal "stand-off" pipe/tubes to be sure to safely clear the exhaust pipe/pipes. Stand-off tubes were used in the original configuration.

I want the filter in the front so you can see my 54 corvette manifold