New member, help identifying engine

Goach2 · Veteran Member

New member, help identifying engine

73SC · A Poncho Legend!

Welcome, we have many experts here so you've come to the right place.

My 261 knowledge is not as great as others but from what I see you have a 261 with a Power Glide, Am I right? You definitely have a Canadian Pontiac that's for sure.

YEAR	ENG. SIZE	BLOCK NO.			HEAD NO.
54-55	261	3703414	3733950		3703570	3836850
55-57	261	3733340	3837012		3703570	3836850
58-62	261	3739365	3769717	3769925	3836850

-- Edited by 73SC on Friday 7th of August 2020 12:47:55 PM

Goach2 · Veteran Member

Hi Ray,

I'm not sure what the tranny is, but I believe it's a 4-speed out of a truck. Is anyone familiar with this combination?:

Block: 3837012
Head: 3835913

long stroke · Canadian Poncho Superstar!

A hardy welcome aboard from Milton, Ontario. Joel, you are going to love the journey here on C.P. Ray (73SC) has given you some excellent information already but my question to you is, what car is it in or out of. The W in front of the casting says that it is without a doubt a Canadian 261. It is probably a 148 h.p. unit. Can you list the other casting numbers on the engine to pin point the year, unless you are sure that it came out of a certain car. This 261 looks like a Chevy 235 but it really is not because there are a number of differences between the two. Many parts are still available for this motor. It is a rock solid engine to own and has plenty of power and torque to motivate any car. Can you tell us anything about the car it is in. Cheers.

Goach2 · Veteran Member

Thanks long stroke, which other castings would be helpful? It's sitting in the bed of my truck, so I should be able to find whatever is needed. I have no information on what this was in, other than that it was transplanted into a '55 1/2 ton pickup.

I'm in Niagara, great to see some locals for a change ;)

-- Edited by Goach2 on Friday 7th of August 2020 01:18:09 PM

long stroke · Canadian Poncho Superstar!

Joel, you have a 1954-1955 Chevrolet 235 cylinder head on your 261. This head would not be original for the 261. It will work with slightly higher compression but, and here is the big but. The 261 has steam holes in the block and original 261 head for improved cooling but the 235 head never had this provision. A 235 head will work but you stand a chance of having over heating trouble.

-- Edited by long stroke on Friday 7th of August 2020 07:54:46 PM

Goach2 · Veteran Member

That's pretty much what I have found as well. I was hoping that this was a setup that might have been used in a Pontiac. I have read up on the steam holes as well, I will have to see if they have been drilled out or not. One post I saw suggested that the '913 head was a replacement for the '848 head, with a change in the temp sensor for a 261. This could be wrong, but I supposed I will see when I do get to pulling it apart. Is there anything else that would be good for identifying where this came from?

long stroke · Canadian Poncho Superstar!

Are you sure that is the correct head casting number. If it is then it would be 1954-1955 Chevrolet 235 head. You can see from Ray's list that your engine casting number would make it 1955 to 1957 261 block. As far as i know 261 motors never came with 235 heads from the factory.

Goach2 · Veteran Member

Some additional pics:

photos.app.goo.gl/99NuefasUuGDFgRD7

long stroke · Canadian Poncho Superstar!

Joel, it looks like your 261 engine block is 1957 vintage. I am going to guess that someone at one time put a 1955 235 cylinder head on it. It must have worked ok for who ever had that 1955 truck, that you say this motor came out of. My other guess is that the 235 cylinder head belonged to that 1955 Chevy truck and the engine block was changed at on time to that 57 261. This is the only sense i can make out at this time. Do you know if the motor can be turned and if so do you plan on a rebuild.

Goach2 · Veteran Member

I think you're right. The story is an old dude swapped this into the truck and died shortly after. It sat for a while until the guy I got it from bought the truck. He said a lot of the mount bolts were still loose. It is stuck, but I hope it's not too bad It MAY not have even run with that head on it. I plan to do a full rebuild on it, which will be my first. :)

long stroke · Canadian Poncho Superstar!

Goach2 wrote:
I think you're right. The story is an old dude swapped this into the truck and died shortly after. It sat for a while until the guy I got it from bought the truck. He said a lot of the mount bolts were still loose. It is stuck, but I hope it's not too bad It MAY not have even run with that head on it. I plan to do a full rebuild on it, which will be my first. :)

If you plan on rebuilding it, just remember that the 261 is very different from the 235 as far as internal parts. Especially the pistons, rods and camshaft. Keep us updated on the work on your 261 and good luck with it. Cheers.

Goach2 · Veteran Member

Thanks, I'm going to have lots of questions for the forums over the months to come :) Quick question, how do you know the block is a 57?

73SC · A Poncho Legend!

I did a lot of research when I was writing articles for the POCI newsletter and came up with that chart posted above as part of an article. The research shows your block falling into the numbers for 55 to 57 and actually being second to last in the series, therefore making it appear to be a late 1957 engine.

Pontiacanada · A Poncho Legend!

Welcome from Canada's east coast!

long stroke · Canadian Poncho Superstar!

73SC wrote:
I did a lot of research when I was writing articles for the POCI newsletter and came up with that chart posted above as part of an article. The research shows your block falling into the numbers for 55 to 57 and actually being second to last in the series, therefore making it appear to be a late 1957 engine.

What our buddy Ray said.

427carl · A Poncho Legend!

My Dad had a '61 Strato Chief w/ 261 It was our first Powerglide auto. It would run just over 105 mph :)

We had in in 66 when I was 17

Goach2 · Veteran Member

Thanks for the warm welcomes and the info. I will start a rebuild thread for this engine. So greatful for the community here and it's willingness to help.

Goach2 · Veteran Member

Well, that was a short-lived dream... https://photos.app.goo.gl/mHXttmQFHoMcLDo39 It's unfortunate, but I'm not totally deterred. I will keep looking.

CdnGMfan · Canadian Poncho Superstar!

Sleeve it and it's good to go.

I'd keep looking. Bummer.

Goach2 · Veteran Member

If someone was going to do a full rebuild, is sleeving worth while on two cylinders? I just want to be sure before I scrap it.

Prefectca · Poncho Master!

When looking for a replacement engine be aware that the early 235/261 engines dont have the mounting holes for the side engine mounts.

Paul

long stroke · Canadian Poncho Superstar!

Goach2 wrote:
If someone was going to do a full rebuild, is sleeving worth while on two cylinders? I just want to be sure before I scrap it.

If you can find a replacement block that you know for a fact is basic rebuildable and cheap, then that would be the best way to go. On the other hand these motors are now very hard to find in excellent rebuildable condition and you may have to sleeve what you got. Another thing is finding a complete running motor that just came out of a 1955 to 1962 because it might have been replaced with a belly button V-8. That would be the most simple and cost effective way to go about it. Find a complete good running engine. These do come up on occasion but you really have to look and it may not be two blocks away from where you live. Good luck mate.

Goach2 · Veteran Member

Some justification for all those who always post about making sure the head has the 'steam holes' that match the block. Look at the state of these holes, all filled with crud because the wrong head was used. What's right next to them? Busted cylinders... https://photos.app.goo.gl/6bW3gJ83d1nCm3hq8 I will continue to break this down and will likely get a price for sleeves. If it's astronomical, I guess that's my answer.

long stroke · Canadian Poncho Superstar!

Goach2 wrote:
Some justification for all those who always post about making sure the head has the 'steam holes' that match the block. Look at the state of these holes, all filled with crud because the wrong head was used. What's right next to them? Busted cylinders... https://photos.app.goo.gl/6bW3gJ83d1nCm3hq8 I will continue to break this down and will likely get a price for sleeves. If it's astronomical, I guess that's my answer.

Joel, i am very sorry to say that there is no surprise there. It is looking like another motor is a better idea. Good luck brother, no matter what your course of action is. Cheers.