The Stovebolt Site Forums The Shop Area Engine Shop 261 casting numbers

My 1958 Chevy pickup's 235 just got tired and I am having it rebuilt. In order to not be rushed on the rebuild I purchased what I thought was a used replacement 235 to put in temporarily while I wait patiently on my original 235 to be rebuilt.

However when I ran the engine block casting numbers I discovered I actually had bought a 261. The block casting number is 3769925.

My question though is with the head casting number. It is 3835913. When I tried to research it I came up with a number that was for a 54-55 235 engine. Did they use the same head for the 1959 261 engine?

Also I was wondering if my distributor from the 235 engine will work in the 261 replacement engine? We were thinking of changing it out in the morning if it will work.

Hy vintage_fishing, yes the distributor will work, as to the head, any head with the correct bolt pattern can be used, but there are some additional holes which should be drilled into the head which were not there on the 235 application heads. Just lay a 261 head gasket on the head and make sure the holes between the center cylinders are in the head. If the engine is together and a good runner I would assume the holes are there, hope that helps.

Thanks 3B. We are just now finishing the install. Out of curiousity what will be the symptoms if the additional holes were not drilled into the 235 head? At this time I am assuming that it has the correct 261 head on it or if a 235 head was used the holes were drilled as you mentioned. I just want to know what would most likely happen or show up if I am assuming incorrectly.

Did the 1959 261 heads have a different casting number than the one I have on the head? Where can I find any info on the 261 head casting numbers?

Thanks again 3B for the help and any additional help would be appreciated much.

If the head you intend to run on the 261 does not have the 6 coolant holes there are those who will tell you it does not overheat and can be run like that. Personally I believe if no flow is present the large temperature differential will result in greatly accelerated cylinder wear. More info here.

Thanks Curt B. I guess for now I will start the engine and watch the temperature gauge. As I mentioned earlier I hope to only have to run the engine for a few weeks until the original 235 is rebuilt and back in the truck. At that time I may take the head off the 261 and inspect it.

I just wish I could confirm the head casting numbers (3835913) were used in 1959 261 engines. There are some other numbers on the left side of the head which are GM13. Also the right side of the head has the number 18B followed by a 913 which sits above the number 241 which sits above the number 670. Any help with those numbers would be appreciated.

My list shows your head casting no. as 54-62 235 & 261s. My want to search for numbers on www.inliners.org
JIm

http://www.oldchevytrucks.com/blog/index.php/?p=754

Your head casting code was used on 1954-55 235 engines. That head was not used from the factory on 261 engines.

What list are you using JiMerit Boltr#43 ? I can not find a list that shows the casting numbers I have used on the 1959 trucks. However I have read other posts elsewhere that mentioned those casting numbers used on the 54 - 62 261's as you also mention.

Also want to mention that we got the 261 installed and started but it was puffing antifreeze out the tailpipe. We took the head off and it too had a cracked head. What a week!! Sending both heads to Dover in Chattanooga, Tn. tommorrow morning. When it rains it pours here.

Is this for a crack repair quote or confirmation and can you share if the extra coolant holes were present?

You might be suprised what might turn up by placing a local classified ad especially online(Kijiji for example)for pre 1963 Chevrolet inline heads. Some rodders may encourage you to get the whole boat anchor out of thier way.

I sent the heads to Dover for repair and rebuild.

Yes, the head had the 6 steam holes.