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A friend has a 1955 261 block 3836340 in his 1952 1/2 ton. The engine doesn't have an external oil filter. He says it has oil slings. Does anyone know what he's referring to?

My bet is that he is incorrectly referring to the dippers on 216 engines. The 261 (and 235 truck )engine from 1954 onwards had high a pressure oil system. The earlier truck engines had dippers on the bottom of the connecting rods (and lower oil pressure). Nonetheless, I believe that either engine could have an external, bypass oil filter (canister--style) attached to in intake manifold.

If "slingers" means something else, I am interested in learning about them. (A dipper might become a slinger if it is installed backwards).

Tim

Well, I think your friend may need to really check what he really has. first- The numbers you gave are the "head" numbers, not the engine numbers. I would venture to say that being as he has a '52 chevy p/u he probably has a 216/235 with "dippers", as Tim mentioned previously. To find out what engine it is you would need the numbers off from the block.

I found the number 3836340 embossed on the block just in front of the distributor. According to inliners.org that should make the engine a 1955-57 261. My friend has offered the engine to me, so that I can replace the 216 that I have in my 1953 1/2 ton. I was concerned that since there is no external oil filter, does that mean oil was not circulating the engine components properly? Or does the external oil filter only circulate 20% of the engines oil? He ran his truck with this engine for eight years until about two years ago. He plans on replacing this engine with a 350. I'll also check the head numbers tomorrow, when we try to start it up again. Personally, I don't think he has any idea, when he says the engine has oil slings.

(I give this a try but remember, you're listening to someone who used to time his 235 using a bolt hole in the flywheel in the bell housing hole on the driver's side.)

The later 235's and earlier 261's had a bypass oil filter where only a certain percentage of the oil from the pump would get filtered. Check where the oil pressure gauge is connected to the block. It should be under the manifold about 3/4 back from the front of the engine. My 235 has a tee at that point which also accepted an oil line. The line went to the filter. The second filter line was connected to the block just above the pan in the middle of the engine. The lines are about 3/8" OD.

If you have the oil pressure gauge connected, they must have blocked off the other threaded hole in the block. The engine would be getting oiled to specs or better but the oil wasn't being filtered. Some folks say the bypass system doesn't work all that well so maybe not much was lost if the oil was changed regularly. You can always add the filter.

58-62 261's had full flow oil filters where all the oil from the pump went through the filter using 3/4" OD lines.

By the way, Jim Carter's Technical Article on the 261 doesn't list that number.

Thanks for the replies. Wally/Montana, you're right, the oil pressure gauge was connected to the block below the manifold and they plugged the other threaded hole. I had not realized the engine was still getting oiled to specs without the optional filter.

Ruck, if I erred on that I do apologize but I had just been looking at a NOS head in the bos with # 3436848 and saw your #'s starting with 383 and figured it for a head #.

This 261 seems to be getting stranger all the time. We couldn't get it started on Sunday, no spark, maybe I can use the coil from my 216. We'll try again next week, I would like to check the compression also. Checked some more numbers, the block had 0591256 F255N on the flat spot to the rear of the distributor, and 3835913 on the head which is for a 235. I haven't checked the head yet to see if it was drilled out for steam holes. Maybe I should just rebuild the 1954 235 engine I bought last year.