How To Identify Your Imperial Engine


Imperial Home Page -> Repair -> Engine -> Identification


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General information on how to identify a Mopar engine:

All engine assemblies carry an engine identification number.  On all eight cylinder engines, the E.I.N. is on a pad located on the right side of the block to the rear of the engine mount. 
In addition to the previously covered E.I.N., each engine assembly carries an engine serial number which must be referenced when ordering engine replacement parts.  On 318 C.I.D. 8 cylinder engines, the engine serial number is located on the left front corner of the block, below the cylinder head.

Mopar engines are divided into several groups:

The slant 6's:170 and 198 cubic inch are known as "G" engines
The slant 6 : 225 cubic inch is known as the "RG" engines.
The "wide" block 318 cubic inch (1958 to 1966) is known as the "A" engine.
The small block V8s 273, 318, 340 and the 360 cubic inch are known as the "LA" engines.
The 361, 383 and the 400 cubic inch engines are known as "B" engines.
The 413, 426 wedge and the 440 cubic inch engines are known as "RB" engines (raised block)
The 426 cubic inch Hemi is in a class by itself.

To locate your casting number, look on the side of your block and compare it to the chart below for engine Id, the date may also be stamped on the block by the casting numbers.

There is also the id stamp on the engines:

On the slant six engines it is located just below the cylinder head on the passenger side of the block.
On the "A" and the "LA" engines it is stamped on the drivers side front of the block just below the cylinder head.
On the "B" engines it is stamped on the top of the block near the distributor.
On the "RB" engines it is stamped on top of the block forward of the intake manifold on the drivers side.
The stamps may include the engine size and also a series number for the year.



There could also be a stamping "HP" or "HP2" designating High performance.

Casting CID Year Family
2202843 170 ??? " G "
2205630 170 ??? " G "
2264478 170 ??? " G "
2464230 170 1965 " G "
xxxxxx 198 1965 " G "
2202857 225 1965 " RG "
2205528 225 1965 " RG "
2463430 225 1966 " RG "
2806830 225 1966 " RG "
2465330 273 1964-66 " LA "
2536130 273 1965 " LA "
2466090 318 1965 " LA "
2536030 318 1967-75 " LA "
2566080 318 1967-75 " LA "
2806030 318 1967-74 " LA "
2780930 340 1968-73 " LA "
3577130TA340 340 1970-71 " LA "
3418496 360 1971-74 " LA "
3870230 360 1975-up " LA "
2264230 318 1960-66 " A "
2468230 318 1960-66 " A "
2532630 318 1960-66 " A "
2120229 361 1960-66 " B" Industrial
2205712 361 1958-66 " B"
2468130 383 1959-71 " B"
3614230 400 1971-72 " B"
3698630 400 1973-78 " B"
4006530 400 1976-78 " B"
1852029 413 1962 " RB "Max Wedge
2120529 413 1959-65 " RB "
2205697 413 1959-65 " RB " Pass Car
2468030 413 1959-65 " RB "
2536430 440 1966-72 " RB "
3698830 440 1973-78 " RB "

Information on 318 (1981-1983):

From Bob:

My 81 Parts Catalog shows only one engine with different heads, valves, rods and mains, gasket sets, rings, crank, chain sprocket, and misc. parts and that is the E48 code which is a Heavy Duty 318 with 4 barrel carb - police work no doubt. The EFI engine heads, including valves are no different that the carbureted 318 blocks. Again, the Service Manual data is not correct. There were also stories at the time of announcement for these cars that each engine part was carefully selected, weighed and measured for uniformity and conformity with mating parts and the final assembly was precisely balanced.

You can find the date that the block was cast, when the engine was finally assembled and the engine identification number, (EIN), from markings and cast-in data on the parts. If you want to see these, let me know and I'll pass on the directions.

I too was deceived by the Service Manual information, because I was led to believe what I'd read about the engine details, they being a cut above the regular production run engine; but the problems I have had with the engine have never been with the iron parts. My family has tried to wear-out eight 318 engines in a period of thirty years, and it hasn't happened yet! The Torqueflight, right behind the block, has done well also. 

Information on 413:

Question from Roger:


I have a 413 engine in my 59 with id-number MR413. I have not been able to find this MR in any identification books. Would be very grateful if anyone could help me to identify this engine.


From Bill:

My resource book only goes back to 1962. I find nothing to indicate what the MR refers to but my first inclination would be Marine. I guess it would be possible to have had a marine engine adapted to replace the original motor. 

Follow-up from Roger:

The serial number is 9878 and the casting number is 1851629-2. Below the casting number is also the letters R . L .  

More Information on the 413:

Question from Bruce (1961):

I am considering a 1961 Imperial that is not in my home town and am trying to determine if the engine is likely original to the chassis. The owner found the engine ID boss that's located around the base of the distributor toward the driver's side, but the ID number he finds does not relate to what Year One says about identifying big block Mopar V8s. He says there is only a four digit number stamped on the engine boss.

It would be most helpful if someone with a 61 could give me an idea of what the ID is like on their car.


From Bill:

Engine numbers back in the early 1960's were not that long. For 1961, the engine number on an Imperial would have had prefix "R 41" or "R 413", followed by digits for the date of assembly. A third digit, "2", after the date meant the car was built on the 2nd shift that date. The car's serial number was not stamped on the block and there is no way to prove the engine in the car was the engine the car was built with originally.

From Steve:

In '61 the Engine ID was not by the distributor. Looking at the car from the front the engine ID number is located on a flat pad directly in front of the valley pan/intake closer to the driver side head. Should start off something like XX 413.

Information on the 440:

Question from Vincent (1967):

I have a 1967 Imperial LeBaron with a 440. I would appreciate it if someone could tell me what the cross symbol on the identification pad means. I have only seen this once before on a 440 engine that came out of a Dodge police car.

Reply from Rodger:

The Maltese cross means you have a bearing that is a different size. The cross should be followed by a number ( or two ). The number(s) will be the bearing(s) that have a different size. It can happen with any factory engine.

Information on 440:

Question from Bob (1968):

I would like to purchase a 440 engine (pulled) I was told from a '68 Imperial for my 66 Imperial as a replacement. Can anyone help me identify the engine markings to determine if it actually is a 440RB. Stamping on the right hand side of the block in very big numbers is: 253643010 and to the right of that is: 27*67. I am guessing the year as 1967 ? On or near the water pump was the number: 2780987 and 2806178. And on the manifold was 2532464. While I am on the subject, what is the going price of a complete (pulled) engine of this vintage with unknown mileage probably original and in need of some work (another words, a donor engine). It had a Carter carb (not an AFB) 4,000 series. Linkage looked the same. Will my trans bolt up to this or is 67-68 different in any way? I told him I would let him know by Wednesday nite if I wanted it. It looked old, greasy, and in need of overhaul but if I took it for parts only what would you determine would be a good price? If I found another (complete engine) in better shape and could hear it run, what would you consider to be a fair price? I was told a low of $300 to as much as $ 1,500, but I really don't know what would be fair.


From Brian:

There is a pad on the front of the block on top just in front of the intake manifold. This is referred to as an RB pad, because it is only there on the RB blocks and not the B blocks. This is where you will find info on the engine such as year, size( RB's were 413, 426w, and 440) and other things such as undersized bearings and oversized cylinders. is a link to the 440 that is in my 69 300 now. I have drawn an arrow to the pad that I am talking about. Scrape the gunk off so you can read it, if it is a 67 440 it will say C440, 68 will be D440, 69 will be E440 70 will be F440 and so on. I have personally never seen a 66 440, but I would have to assume it would be B440. Sounds like to me the 27*67 is the casting date, probably 2-7-67. They casted the blocks for 68 in early 67, so it sounds like a 68. I don't know anything about the other numbers, but I am sure someone else on the list will be able to decipher them. In my area an engine like you have described would have a value of somewhere between $250 and $500.

From Rodger:

At the local shopping center (A-1 Auto Salvage) here in Colo Spgs they sell any engine / any year / any make for $ 80 dollars.

With the water pump pointing at your belt buckle look to the right area slightly above and to the right of the distributor. There is a flat machined area. 413's, 426's and 440's have a code stamped there. C440 = 1967 440, ...D440 = 1968, ...etc No flat spot with no stamping means it is not one of the RB family.

Yes it will bolt to your transmission.

This page last updated December 9, 2003.  Send us your feedback, and come join the Imperial Mailing List - Online Car Club