The Stovebolt Site Forums The Shop Area Engine Shop 261 ID Questions, and Oil Filter Parts Needed

Hello everyone! I've recently obtained a 261, judging by the casting marks I believe it's a 1958 model. However I'm curious as to what it was originally in. I'll post a photo of the serial number on the ledge by the distributor, as well as the casting numbers on the block. The serial number is FIII8L (Those are capital i's, not lower case Ls). This doesn't match any kind of 261 serial data I've found on the internet. When I got the engine, it was in a 1950 Chevy 3800 with a 3 speed transmission, so I know it was swapped out of some other vehicle.

My second question is about the oil filtration system. When I got this engine it had a bypass oil filter system on it, but I'd like to convert it to full flow. I'll put an ad in the classifieds for the parts, but I was wondering...to set it up for full flow, do I need to push the pin on the side of the block in? If so, do I just push it till it stops, or is there only a certain distance it needs to go?

Thanks guys!

Yes, the pin needs to be pushed in to use the full flow filter. No, I DO NOT recommend trying to do that. The pin will be extremely tight, and it will require some vigorous hammering to make it move- - - - -possibly causing the block to crack. It would be much safer to pull the plug out of the block by drilling and tapping it for a piece of all thread rod, and using a piece of steel tubing, a nut and a washer. Then, thread the hole for a screw-in setscrew to block off the oil passage from the oil pump to the main oil gallery. Use red LocTite on the threads to make the plug a permanent installation.

Send me a private message- - - -I have a full flow filter canister, with lines, that I'll never use.
Jerry

Edit: It might be possible to push the pin in safely by using a big C clamp, or something similar like a ball joint press, with the oil pan removed first.

Thanks Jerry. Would any harm come about if I just heated the block slowly with a torch first, then hammered it in? The engine is out of the truck, so getting space to work on it isn't a problem. I sent you a PM.

Jerry's suggestion on using a C clamp or ball joint press is the way to go. WAY less chance of cracking the block than hammering on it.

Heating MIGHT reduce the chances of cracking while hammering, but not worth the chance, IMO.

I've searched the forum to read about the topic, and that seems to be the consensus- it's really hard to move, but if you must, take your time and be careful.

The engine number indicates it was built in Flint Michigan, the numbers indicate the date built (11=November, 13 day of the month), and L indicates it was originally built for a 6000 series truck. There really isn't a serial number for the engine just the date code, so all engines built on the same day would have the same numbers.

Thanks for clearing that up! I didn't realize it was just a date code.

If you don't want to try & drive the pin in you might be able to tap & plug the vertical main oil galley to do full flow filter.
This is what I did to use a spin on full flow on my 261, replaced canister w/ spin on filter. Had hoses made @ local NAPA, uses a fur* filter (NAPA 1068).

BC...that's a very fine looking job you did! I may end up making a set up similar to that.

I've been working on my engine, and I decided to chance it by heating up the block and seeing if I could drive the pin in. It was successful, once it started moving, it moved a little with every hit until it felt like it bottomed out. I've read on this forum and in other places the depth of the plug should be 9/16" but mine is only 3/8" deep. Does this look right to you all?

Here's a quick way to check- - - - -when you remove the plug just below the pin, try to push a piece of stiff wire past the plug. If it's in far enough to block the passage, the wire will hit a solid stop. If you can push a thin wire past the plug, it needs to go in further.
Jerry

Should be able to check with air pressure.

How would that be done? Maybe pressurize the main oil gallery and listen for leakage below the pushed-in dowel? Lots of leakage possibilities from the rod, main and cam bearings- - - - -and no way to check from the front port without pressure escaping backwards through the oil pump.
Jerry

In my experience installing a full flow filter is more trouble than it's worth. On cold startup it takes longer to get oil to the main gallery where the gauge fitting is; there is the issue of leaking hoses and hoses getting fried over time by exhaust heat (which on a hard pull will run about 1,200 Deg. F); the full flow filters available filter average particle size of somewhere between 25 and 40 microns (if you can get the spec at all) and the spin-on canister's quad ring can leak along with all the other connections. You can set up a very fine bypass filter in the range of 5 microns made for hydraulic systems that will keep the oil much cleaner. I would do this anyway even with a full flow filter. I did that on mine and oil analysis shows insoluable particle count approaching zero after 5,000 miles. Averages are 0.6% and mine at 0.2% per Blackstone. I use an old-time Franz toilet paper filter.

That's my opinion exactly- - - - -a spin-on Diesel fuel filter plumbed in bypass mode will filter the oil better than any full flow could ever achieve, and there's no reason to use flex hoses as long as the filter adapter is mounted to the intake manifold. Copper, or copper/nickel hard lines work better, especially if a spiral vibration loop is incorporated into the design.
Jerry

Well...I wish I had known that before I pushed the pin in. That's a pretty convincing argument for the bypass system. I didn't know those kinds of results were achievable with that bypass setup.

You can drill and tap that pin for about a 5/16-24 thread, and use a bolt, nut and flat washer to pull it back out to the non full-flow position if you choose, or leave it in and add a fine mesh bypass filter to get the best of both worlds- - - -the full flow to strain out the rocks, marbles, and bowling balls, and a fine media bypass filter to get the small stuff that goes right through the other one!
Jerry

LOL that's pretty funny Jerry

'You can drill and tap that pin for about a 5/16-24 thread, and use a bolt, nut and flat washer to pull it back out to the non full-flow position if you choose, or leave it in and add a fine mesh bypass filter to get the best of both worlds- - - -the full flow to strain out the rocks, marbles, and bowling balls, and a fine media bypass filter to get the small stuff that goes right through the other one!
Jerry'


What I've always wondered, when filtering only in bypass, what happens when the rocks, marbles and bowling balls aren't filtered out of the oil stream? You're inevitably going to get the odd piece of dirt in the oil pan while changing or checking the oil. What happens when that piece of dirt flows through the crank and gets pushed through a main bearing?

That quote is plaigarized- - - - -that's what Carter carburetor said about the screen mesh inlet "filter" that most carburetors had, compared to the sintered ceramic inline fuel filter they sold. To be really effective at filtering oil, a system would need to have both a full flow and a bypass setup. Cummins diesels ran two filters for a long time, one bypass and the other full flow.
Jerry

In reality, how much dirt or solid debris is in your engine anyway?

Engines ran for half a century without oil filters. Frequent oil changes were/are really all that's needed. If you have metal in your oil, you have bigger problems to deal with.

I've always been curious about such matters and many times I've taken a hacksaw to spin-on filters and have also cut open paper element style filters on all kinds of cars.

I've never once found "dirt" or anything that would harm an engine if it weren't filtered out. I'm a stickler for the 3000 mile change interval on all cars regardless of age.

Recently, however, I changed the oil in a 2008 Honda that has a light on the dash that tells you how much oil life the oil has left in it. It decides this by tracking driving habits, engine hours, miles, etc to determine the optimal time to change the oil. This oil change was 8500 miles.

I opened up the filter and it looked practically new. Oil was clean and there were no rocks, marbles or bowling balls present.

Under normal driving conditions on a well maintained engine, I don't think there's really a need for an oil filter. It gives us peace of mind, though.

The real engine killer is blow-by gases rather than solid materials floating around in the crankcase. Frequent changes are the best way to deal with that problem.

I attended a seminar on diesel marine engines conducted by a field engineer for Detroit Diesel. Most of the people there were owners of high dollar boats with one or two diesel engines. Somebody asked "How long does a Detroit engine last?" The answer was simple- - - - -"Long enough to eat two pounds of dirt!". The engineer was referring to dust ingested through the intake, but the same thing applies to contaminated oil. Clean oil and/or air is essential to engine longevity. The same engine that will run 200K miles under clean conditions will wear itself out in a fraction of that time if it runs dirty- - - - -air or oil.