The Stovebolt Site Forums The Shop Area Engine Shop What engine do I have

Hello All,

below should be some pictures from one engine that I got given to me with the purchase of my rebuild 1953 Chev 1/2 ton.

Any knowledge what I have and if it is worth rebuilding?

Casting numbers

Looks like a 1958 or later 261.

Okay, Gord,

This is what I can find for numbers. What says what?

GM - Oldsmobile engine?
Casting # Top of engine, left side of head cover 3886348 GM7
Right side, rear of the block, behind starter 3753365
Stamped behind timing shaft hole W162997 then 2917C

The block casting number is 3759365. The head casting number ends with 848.

Searching the site as mentioned earlier reveals that the block casting number corresponds to a Chevy 261.

The Chevy 261 was also found in Pontiac's. Don't know if they were used in other GM products. .

Numbers stamped beside the distributor can be misleading. Maybe since it's been stamped twice it has been rebuilt?

Canadian Pontiacs ran a 261 with an 848 head and hydraulic valve lifters. It's slightly different (some say better) than the 261 truck engines used in the USA.
Jerry

Thanks Gord & Jerry,

Below is the zoom stamp from the 261 head. Sure hard to pinpoint if the 3rd number from the right is a '3' or '8'. I had it read like a '3', but it is similar to the '8' far right. The '3836' is then the actual serial number of this head, I assume.

I will investigate this further: '9. 1958-1962 235 and 261 truck engines used a solid (mechanical) lifter (tappet) that had an annulus around the lifter body for passage of oil to the rocker shaft assembly. Earlier mechanical tappets (lifters) should not be used in these engines (but hydraulic lifters could be used).'

More pictures, this time of the lifters & push-rods

Casting number 3836848 was used for the high compression head on the USA 235 engine beginning in mid-year 1957, I believe. The Canadian passenger car 261s also used the 848 head, possibly modified with six extra coolant holes to facilitate better cooling of the siamese-cast cylinder pairs. With the extra displacement of the 261, an 848 head would make it a real performer. A couple of those lifters show a hydraulic plunger bottomed out due to the valve being open with tension on the spring, which also strongly suggests you've got a 261 passenger car engine with a hydraulic cam.
Jerry

One question, again, the engine has no oil pan. Are they different for the different 6L engines and I need to find one to match the 261?

Biermann - It's possible your block casting number might have been misread. It could be 3739365, which from my US reference resource indicates a 1960-63 Truck 261. It could be your Canadian 261 used the same casting number as the US truck engine, but I can't find anything confirming that. I think a 1958-62 235/261 oil pan may be what you need as they where the same block design and mounting bolt count.

Perhaps you can post an overall picture of the oil pan mounting surface, plus try and find the block casting date codes/marks tobetter ID your engine?

Hello Dan, I share your thought about the '865' & '365' miss-reading possibility and will do as you suggest once I have time to turn the engine over. It is kind of stuffed-away right now, on a engine stand, but I need to see if I have room to turn it upside-down.

Give me a day and I hope I can supply

No hurry Biermann. I look forward to seeing what you find when you can get to it.

Here we go

Looks like what you have is a 58-62 261. That's what 3659365 translates to, and it has the bulge in the side of the oil pan mounting to clear the oil pump. Also looks like it has the captains bars just above and to the right of the block casting number.

6848 head is off of a 235... 1956-1962. The block is a 261. I wonder if the head was drilled for the matching steam holes in the block? The 261 head should be a 3836850. No problem... it was done all the time back in the day.

Jethro - His 261 is a Canadian engine which also uses the "848" head and came with the steam holes. Canadian 261's were also used in Canadian Pontiac's, which used a hydraulic cam and lifters instead of the solid cam/lifters in truck 261's.

Got it!