i'm in the process of building a 454 but was looking at keeping the original block since it is suppose to be a #s matching block and found a crack in one of the journals. so before i attempt to fix it i would like to know if it is real. the only #s we found were 3855961.it is a 66 ss. thanks for your help
john h. :confused:

It appears to be the casting numbers for a 66-67 325hp 396 2 bolt main block.


Rocky

thanks but how can i tell if it is an original block if i don't see any other #s on it or, should there be more casting #s? I was told at the time of purchase that it was original and the 360 hp engine. is there any other way to tell? :(
john h.

John,

The 3855961 block is correct for 325HP and 360HP (360HP also used 3855962) 66 Chevelle and El Camino 396 engines. They were also used on 1965 and 1966 325HP full size Chevrolets.

All Chevelle engines have an assembly code and suffix such as T1207EM which indicates the date of assembly with a 2 or 3 letter suffix code indicating configuration (horsepower, transmission). This code is stamped on the passenger side front of the deck surface. There is also a partial VIN such as 6FXXXXXX, where the letter represents the assembly plant and the Xs represent the the last six digits of the vehicle identification number. This partial VIN is stamped at the vehicle assembly plant and should match your car. If the partial VIN matches your car then this is probably the original engine. If these codes have been milled off during a rebuild, and are now non-existent, then you are out of luck, although you could still look at the casting date of the block (located on the side close to the starter) to see if the casting date fits with the build date of your car. This might tell you that the block could be the original.

Originally posted by AZCamino:
John,
There is also a partial VIN such as 6FXXXXXX, where the letter represents the assembly plant and the Xs represent the the last six digits of the vehicle identification number. This partial VIN is stamped at the vehicle assembly plant and should match your car. I thought the stamping of the VIN wasn't mandated by law until 68 or 69 and some plants stamped the VIN and some didn't before that. In any event, it should have the engine ID code as mentioned unless it's been decked.

Dale,

I'm not sure about the legal requirements, but it was at least GM policy to stamp the partial VIN in passenger cars. All of the 1965 and 1966 passenger car 961 blocks I've seen have the vehicle numbers stamped in them.

Now trucks are different story, and El Caminos were considered trucks. It is my understanding that trucks were exempt from this requirement. I heard that El Caminos built at Fremont, which also built trucks, may or may not have the VIN sequential stamped in their blocks. I know of one Fremont 66 El Camino with a EM coded big block that is not stamped with the VIN.

What did start in 1968 was the requirement to stamp service replacement parts with serial numbers. This was the beginning of the CE coded replacement engines that are now seen.