Inliners International Forums General Discussion Engines 261 oiling

Ok, I'm confused............. I have a late 261 engine. If I eliminate the filter (bypass it, from the outlet to the inlet), should the pin be IN or OUT? Also, shouldn't there be a restrictor fitting in the bypass and if so isn't there a chance this bypass will get plugged up with a tiny particle of dirt?

Dear Ron;

If you have the #2 design (with pin) you don't need the 'by-pass'. Simply pull the pin out flush, if It's not that way already.

Same as I explained to Mr. Hoyt.

Good luck.

well, I'm not sure if I have the #2 or the #3............. The holes are 12" ntp and it looks like there's pin in the in position. Should I just leave the pin where it is and run the bypass or pull out the pin and run the bypass? Not trying to sound stupid......., just comes naturally.........

R;

If it has the pin, It's the #2 design and the 'by-pass' is NOT needed.

You move (take 4) the pin. :rolleyes:

Happy trails.

The engine is in the truck and I can't get in there to move the pin si I'll just use the bypass.

Hi wonton, If the 'pin' is flush with the outside of the block it is in the factory position to be used with a bypass filter. If it has been driven in it blocks off the main oil galley and you MUST use a full flow filter, utilizing the 1/2 inch tapped holes, or you will toast your bearings. Also, be sure the 'in' side of the oil filter adapter is being fed from the oil pump fitting or the check valve in the filter will block the oil from your engine, and you will toast your bearings. The 'pin' is a drive fit, and once seated was not designed to be removed or repositioned. Just my experience, Tim II#498

Tim; alright, now this makes sense. Can you tell me this; if I leave the pin in and just use a bypass line; 1. Do I need to make the bypass 1/2" pipe? 2. If I use a large (1/2") line wont my oil pressure gauge show little or no pressure?

Hi wonton, I think your main confusion is the difference in a 'bypass filter' and a 'full flow filter'. A bypass filter takes a small, 1/8" or so, line from the main galley and sends it thru the filter, and then dumps it right into the crankcase cleaning a small fraction of the oil (basically useless in my book). this type of filter does need restriction or you will reduce your oil pressure. A full flow filter, which is what the pin on the 261" is for, takes the oil from the pump side of the galley, sends it all thru a filter, and back into the oil galley (no oil loss). If you have a block with the 1/2" pipe threaded ports and the drive pin, what I would do is run #8AN fittings and line from the pump thru the filter and back to the galley. As I said in my previous post, be sure the pump outlet on the block (forward port) goes into the 'in' side of the filter. Also, if the pin is driven in, you MUST set it up like this (with the large lines)or you will have NO oil flow to the bearings, however if the pin is flush with the block you can still use the large lines and full flow filter, but it will only filter a portion of the oil and with no pressure loss but still look cool. Again, just my experience, Tim II#498

Hi again, Why do you want to remove the oil filter? One of the best things about the late 261" block is the addition of full filtering capabilities to the oil system. Tim II#498

Dear Tim;

It's because these (remote) filters present far more of a fire/explosion hazard, than the "cleaner oil" benefits could ever provide.

One simply changes @ 3000 using commercial oil.

The pin is the same diameter throughout an surounded with a copper bushing, where 'relocation' is not a problem. Sometimes there is some temporary seepage. Some just remove totaly "tap" and install a threaded plug, on the (2nd design).

The "by-pass" line provides equal distribution of oil W/O the filter unit, on the (3rd design).

Ron is using it (#2 model) to avoid moving his pin etc.

Happy trails.

Hi John,
If the remote filter was a fire hazard on the trucks it would seem that the reason would be the filters were mounted on the intake manifold and the fabric covered hoses looped the exhaust manifold (plus improper maintenance). With the filter mounted remotely and all lines properly routed there would be no problems. As far as I am concerned a full flow filter system is the best protection your engine could have.

Tim II#498

W;

The early 'by pass' filters ran 15# pressure to the filter and gravaty feed drained that 20% of the engines oil back into the pan. These were never a problem like you say and didn't require large oil lines.

The 261 system runs 60# and around 50% of the engines oil through those with this filter. The hoses were much stronger like the ones used on P/S units. They were designed for 'flexibility and normal engine temps".

Still; with that much pressure next to the 1700+/- degree exhaust, they didn't work safely and why the GM warnings were sent out, causing many to be removed in the 60s.

With today's oil, there even less of a benefit.

T;

That filter requires a 5/16 ID line to keep an equal volume of oil/pressure to everything and no matter how/what you built it with, you can't escape the heat generated and location (stock) or that added with headers.

NO TYPE of oil line** is designed for this type of constant exposer/abuse etc.

Under these conditions (hi-pressure + hi-temp) a "pinhole" leak can/will cause a fire/explosion creating major damage almost instantly!! So FAST that the driver will barely be able to escape, should this event occur at 'highway' speeds.

I saw the results of this several times in the mid 60s and the amount of destruction involved is beyond description. The ONLY example I can think of is the car bombs we see on the news frequently.

It was a very BAD DESIGN that was discontinued 40 years ago and should stay that way.

Happy trails to all.

**Remember; 'braided lines' are rubber inside.