The Stovebolt Site Forums The Shop Area Engine Shop Deciphering my Chevy stovebolt

What year transmission & rear end?

The Shop Manual and Operator's Manual for that/those years will tell you the grade of gear oil needed. If you do not have those manuals, they might be on-line. The brand of the oil is not significant, if the oil meets the grade-specs.

I ordered the operating manual a few days ago, it should be here any time soon, I hope it specifies what oil to use, I think the rear end is one of the most neglected parts of a vehicle. On another note, I just got the throttle-choke cable bracket, hopefully it will install well.

What year transmission & rear end?

Some of us have manuals.
Many manual are on-line.

Hi Tim, I have no reason to believe the rear end has been changed on this 46 Chevy 1/2 ton. The transmission also seems to be the same, 4 speed granny no synchro. I might get to it today, it will be raining in Northern California for the whole week.

Classics4Me,

The specs in this 1942 Owner's Manual should pertain to your year.
See if those specs match the specs in this Shop Manual.
Here are capacities/amounts at the beginning of that chapter in the Shop Manual

Underfill it a little when the gear oil is cold.
Then, check the height of the gear oil after a long enough ride to heat up the gear oil.
Then, top-up the oil to fill to the height described in manuals.

Leaks are common
- put a disposable diaper on the floor in appropriate locations; AND,
- check the fluid/oil levels with a regularity appropriate to the drippage rate.

The common old saying "if it ain't leaking, it ain't got no oil in it" was (and often is now) no joke.

Thanks Tim, I had never heard of Mineral oil, but it looks like it accepts "all purpose oil" also "universal gear oil" as long as it's 90 weight. You learn something new every day I'm getting on it today. Thanks again.

Hello again Tim and everybody else that has been kind enough to help me. I finally took pictures of the heads exterior Id #. It's in the picture below. I also took the carb off. Besides the custom choke bracket, I found out it also has a custom center bar (don't know what it's called, but I'll probably have to replace that piece too. The choke butterfly's control, where the choke cable hooks up was turned what I believe is 180 degrees or upside down. I can't seem to figure out how to flip it back to stock configuration. Is this something best left to the pros? I almost feel like getting a rebuilt carb perhaps a carter as was suggested but am afraid I won't be able to connect the choke and throttle cable to it. Also, this carb is working fine and don't currently have the means to purchase another carb. I hope you guys can help. Thanks ahead of time.
Head id #

custom bar-upside down choke cable hook up- new throttle/choke bracket

how carb was setup incorrectly, choke cable should pull from opposite side

carb top view

P.S. How the choke cable was set up did not allow for the chokes butterfly to fully open surely robbing some performance from the engine, also the base for the air cleaner to carb had no gasket nor did the air cleaner to base have a gasket, this would I think allow for a minor vacuume leak if I'm not mistaken potentially robbing more performance from the engine, hopefully I can remedy all these problems when the carb is set back to stock

Head casting code: 3836850 = 1957-1963 261 head

There is a head-date casting-code under the valve cover on the left rear of the head. This one is L 17 9 = 12-17-1959

Hey Tim, I finally got the valve cover off to paint it, here's the inside code, I appreciate the help deciphering the codes, it's been of great help.

Head code

Painting Chevy Emblem

Chevy Emblem

Head casting code: 3836850 : 261 for several years
Head date casting code: J 3 6
J = 10 = October
3 = 3rd
6 = 1956

Nice, a 1956 261. Runs like a champ, now I'm just detailing it. Pictures to come soon.

I installed my 261 in a step van and hooked up oil lines and filter. I just discovered the issue of the position of the dowel for full flow. I purchased the engine rebuilt and the dowel is in just about 1/8 of an inch. Now that the engine is installed, I have very little room for a hammer to get it in any further. I am getting some oil to the rockers, but not a lot to the front. Looking for advice. Just leave it & install smaller lines? A good trick to get the dowel to move? Suggestions or comments welcome! Thanks.

Hey Chaz, sorry my friend, mine didn't come with the bi pass oil filter so I don't have a good idea of how it should go. Its a sweet engine though. Heres a picture of what mine looks like now that its detailed a bit.
261 Jobmaster

Back to work Chevy

right side

46 Chevy flowering cherries

Beauty engine! Looks great! What year is yours? Dowel in? I'm a little surprised that this topic is still somewhat in the unexplaned category. I did find a pic of a 1960 engine like mine that had the dowel recessed the same amount as mine, about an 1/8th. I don't think it is a coincidence either. Mine does not have the small port to the left of the oil line under the doewel either. My suspicion is that this one is set up for full flow only. I will turn the oil pump and see what happens. Does anyone have a post 60 261 engine with the dowel 5/8ths in?

Fortunately I have a few of these fine engine laying around.

Here is a photo of my 261 in the truck, with the dowel pressed in.

Dowel in

Here is a photo on one that is out, or in bypass mode.

Dowel flush

Thanks Chaz. Mines a 1956, Tim, who posted in previous comments, helped me decipher what it was. I'm very happy with it. It's already hauling stuff. People give me that look like they can't believe I'm using my classic truck for work, but trust me, that's what they were made for, that's what will keep'em young.

Sweet,

I hope you do not mind that I copied your photos and lightened up the dark one (the "plug-in" photo), and then I put those photos on a quick-and-dirty web page, side-by-side.

1958-1963 261 engines oil filter options

If anyone has a 58-63 261 block and can take a good photo of the "port" for the by-pass filter lines, please post a link to the photo and I add it to that web page.

If anyone has a 58-63 Canadian 261 block and can take a good photo of the oil filter "ports", please post a link to the photo and I add it to that web page.

Thanks,

Tim, great idea. Do as you wish with any of my photos.

I have a photo of the smaller ports, Tim check your email.

I noticed today that my engine does not have the 1/8 plug to the left of the 1/2 out oil line. I decided to heat up the dowel some just to se if it would give a little-NOPE. I read on a post that some dowels were out but still had full flow. Pad the room for me fellas!

So I am getting full flow with the dowel in the out postion. it was not fully flush with the block, in about an 1/8 of an inch.

Chaz, can you take a photo and post?

I already have the updraft carb in Sweet. It unfortunately obscures a picture of the dowel in its out position.
Here is a picture of another 261 that has its dowel in the same position as mine.

http://www.chevytalk.org/fusionbb/showtopic.php?tid/311269/

Chaz 58,

If your pin/plug/dowel is in this position, it is the "In" position (we think) and we suppose that means a full-flow oil filter is required (or a hose/line from port-to-port on the block is required).

That is not in far enough Tim. In is .63 or 5/8" in from flush with the boss. That is pretty much still in bypass.

Pics and more here:
http://devestechnet.com/Home/TheVenerable261

Here is the proper depth:
http://devestechnet.com/Images/Restorations/1950B/D50b00489lg.jpg

Yes, it's only in about 1/8th of an inch. I have read other posts that had an "out" dowel & still had full flow.

Please note that unlike the engine pictured, mine does not have a small port/plug to the left of the 1/2 oil port.

CHaz 58,

What is the block date casting code on your engine? Thanks

http://www.1954advance-design.com/Web%20images/casting-code-photos/codes-ser-nums.html

5/8 is .625"

Ed

yup. There are a few different paragraphs on the subject. I have seen .63 and 5/8" so take your pick. The dowel itself is 1 inch long. It has to block (or not) an internal oil passage.

http://devestechnet.com/Images/ChevPartsAccessories1929to59.pdf

bottom of page 2

The date code is F40, June 4 1960.

Thanks, Chaz,

I will have to check my 1960 261 (it is now in a distant land) to see if it has the "small port/plug to the left of the 1/2 oil port". I'll also ask my friend with a 1959 261. There might have been differences in this "feature" between 1958-1963?

The more we think we have things figured out, the the more we find that we do not know.

How are you determining if you have full flow or bypass? I am just thinking out loud here, but that wouldn't be obvious.

If you spin the oil pump with the both inlet and outlet plugged/capped off, and you get oil at the rockers, it's in bypass. Not sure of a better way to check.

I think Tim is correct about the late 261 engines.
I was getting oil to the rockers, but I was not sure if a significant amount of oil was getting to the filter. I took the filter off and turned the engine over a few times. I lost about half a quart, so it was coming out very good even without the engine running.

All of mine are late 261's and they work as I have stated. If you plug both lines at the block and get oil to the rockers, it's in bypass. If you get NO oil to the rockers it's because you blocked the path via the dowel.

The full flow path is:
The front outlet - pulls oil directly out of the pan and goes nowhere else until it flows through the filter and into the engine via the rear inlet. Plug either of those and the engine is starved completely. You must use a full flow filter that does NOT have a restrictor.

Bypass: You can plug either or both holes and there is an internal passage that will allow oil to get through.

So, if you think it is currently in full flow, there is no oil going to the rockers as pictured. Pushed all the way in, full flow. Remember though, once you push it in, you can't easily pull it back out so you want to make sure of your decision to go with full flow.

What years for you late 261s, Deve?

Do they all have that small "pipe plug" to the left of the left full-flow port on the block?

Yes, all have the plug beside it. I have a 717 and two 925's (3769). If there is a block out there that does not have that smaller port, I guess it IS possible that it is full flow only, but not real possible for them to be backwards since that would require a major internal change.

Since I have the 261 document on my site, I get phone calls all the time about this issue. Each time everyone has the same dowel action. The dowel hole is 1-5/8 inches deep. When out, bypass, when all the way back, full flow. The way to test is described above. With bypass, about 12-18% of the oil is filtered, with full flow all of it.

As you said though, there could be a block out there that is completely different but with the 717 casting code?

What are the date casting code years on your 261 blocks, Deve?

Tim, you know what a pain in the butt you are right? Making me actually look, what a concept. THANKS! Here is new information..

The 717 has NO small port. That news however is negated by the fact that this engine has the dowel pushed all the way in to the 5/8" depth and has the large pipes running to the non-bypass filter. F0711LB / G 81 / 3769717

The 925's are L 17 4 and that one is a replacement no serial
the other is G 22 and F0703J.

First time I noticed that one of the later castings has no small port. I guess they really aren't necessary since they can be adapted.

If the filter you are using is original, remember it makes a big difference if its bypass or full flow. The bypass model will have a 1/16th" restrictor inside the canister. That is not desired for full flow at all. Match the filter to the flow style.