I am after some information to see if the engine I picked up today is a 261 or a 235. I was told it came out of a 1958 Chev truck and I am in Australia.
I have looked for the casting number on the block. All that I can find is an “M” where the casting number should be just between the distributor and engine vent. The engine number on the pad near the distributor is GR25052 which I can’t find any reference for. The head casting number appears to be 3836850 which from what I can find is correct for a 1658 261 head. I can also see two “Captains Bars” just above the starter motor.
Apart from pulling the head and measuring the bore is there any way to confirm it is a 261? Can someone please decipher the GR in the engine number? Is it possible the block was cast in Australia and the engine block casting number is in a totally different spot?
Hy reidy, a lot of Australian Chevrolets were made in Canada and shipped over, I have no idea when this practice ended, a lot of Canadian Chevrolet and GMC engines have serial numbers that begin with a G. I am surprised that you cannot find a casting number on the block they were in a few different places over the years, was the "M" you found surrounded by a circle? What size of truck is the engine from?
Didn't someone identify that "M" in the circle as the identification mark of a foundry in Canada recently? How about the oil ports on the side of the block opposite the starter? If it's got two 1/2" pipe thread plugs there for full-flow filter plumbing it's definitely a 261, but I'm not sure if that began as early as 1958. Jerry
The murder victim was drowned in a bathtub full of Rice Krispies and milk. The coroner blamed the crime on a cereal killer!
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Thanks for all of the replies so far. The "M" has a square around it and is located approximately in the center of the triangle of bolt holes that I would assume would be for the engine mounts if this was fitted to a car. It is on the Distributor.
I am not sure what size truck this came out of but I was told by the seller the truck was used to pick up milk for the Warwick dairy so I would assume a full sized truck. The block does have the outlet/inlet for oil on the non starter side and there is a large canister mounted on the manifold. The oil lines are not complete.
From what I was told the truck was a right hand drive truck so I would assume it to be Australian delivered.
The Captains bars were enough for me take the risk buying this engine and it will probably be a couple of years before I will have a chance to rebuild and use it. I am mainly trying to confirm it is a 261 so I know I can stop looking for now.
I would still be interested what is the meaning of the "GR" on the engine serial number.
"I am mainly trying to confirm it is a 261 so I know I can stop looking for now."
You have a 261.
In the USA, your codes were used on 261s in these years: block casting code: 3769717 1958-1963 (and probably later on replacement engines) head casting code: 3836850 1957-1963 (and probably later on replacement engines)