How to Identify a 440 Six Pack Engine

Knowing how to identify a legitimate 440 Six Pack engine or block is crucial when inspecting one for sale, placing value on it or finding one for a car. For this reason many people ask, how to determine a real 440 Six Pack engine or block?

3 ways to identify an original 440 Six Pack engine:

  1. Match the stamped partial vin on the side of the engine block to the vin of a known original V or M code car.
  2. Be 100% certain an engine hasn’t been rebuilt and the internals of the engine are found to have parts unique to a 440 Six Pack engine.
  3. 100% certain a 440 Six Pack engine was pulled out of an original V or M code car. Also, have paperwork or documentation indicating the vin number of the original V or M code car.

This article will dive deeper into each one of the ways to identify an original engine. In addition, I’ll discuss easy, quick ways to eliminate an engine as an original.

The following 440 specifications and facts were learned from my personal experience and research, Mopar engine manuals, webinars, books, videos and articles.

Identifying an Original 440 Six Pack Engine or Block

There are many 440 engines for sale and some of them claim they are a 440 Six Pack engine or block.

Of course an original Six pack engine will be worth more than a regular 440 engine or block. Some people may have an original V or M code (6 Pack) car without its original engine and wants an original block or engine to put in it.

The V in the vin indicates a Six Pack or 6-BBL for 1970 or 1971 cars. The M in the vin indicates a 1969 Roadrunner or Super Bee A 12 car.

Knowing how to identify an original engine is important for the reasons mentioned.

The presence of three two barrel Holley carburetors sitting on top of the engine isn’t enough proof.

A deeper oil pan or an external weighted damper is not enough to identify an original either.

The truth is there is no difference between a Six Pack block and a regular HP 440 block.

Therefore, let’s take a close look at the ways to help identify one.

The Partial Vin on the Block

Partial vin numbers are stamped on Mopar engine blocks beginning in 1968. They are the last eight digits of the car’s vin number the engine was installed into.

The partial vin can be found on the lower passenger side of the block, just above the oil pan. It will be stamped on a long, smooth narrow pad. Below are some examples of partial vins.

The eight digits will begin with a number, followed by a letter and then followed by six numbers.

  • The first digit of the partial vin (a number) is actually the 6th digit of the car’s vin.
  • The 2nd digit of the partial vin (a letter), is actually the 7th digit of the car’s vin.
  • The last six digits of the partial vin (all numbers), are actually the 8th, 9th, 10th, 11th, 12th and 13th numbers of the car’s vin.

The first digit (number) of the partial vin identifies the year of the car. The number is the last number of the year. Therefore:

  • The number 9 indicates the year 1969.
  • The number 0 indicates the year 1970.
  • The number 1 indicates the year 1971.

The 2nd digit in the partial vin (a letter) identifies the assembly plant of the car. The following letters indicate which plant:

  • A: Lynch Road
  • B: Hamtramck
  • D: Belvidere
  • E: Los Angeles
  • F: Newark
  • G: St. Louis
  • H: New Stanton
  • P: Wyoming (Export)
  • R: Windsor

The 3rd to 8th digits of the partial vin (all numbers) indicate the vehicle sequence number in the assembly plant.

If the engine is sitting in an original V or M code car, the partial vin stamped on the block should match the last eight digits of the car’s vin. This would identify it as an original 440 Six Pack engine.

If the engine is not installed into a car, the partial vin needs to pair with the vin of an original, verified V or M code car. This would identify the 440 as an original 6-BBL engine.

All 1969 Six Pack engines will have the letter A in the partial vin.

This is because all 1969 A12 cars were assembled at the Lynch Road assembly plant located in Detroit, Michigan.

Engine Internals

There is only one way for this identification method to be correct. You have to be 100% certain the engine was never taken apart or rebuilt.

This is extremely hard to prove. Even if the engine looks original or old, many times an engine was rebuilt years ago making it appear as factory original or sealed.

If there was a way to prove the engine was never apart before, it can identify the engine as an original 6 Pack or 6-BBL.

Certain identifying features of an original engine was different from a regular 440 engine block. Believe it or not. It’s not the connecting rods.

Anybody can slap a trio of carburetors, an intake or a deep oil pan on a 440, so it’s nothing on the outside of the engine. It’s all in the internal parts.

Original 440 Six Pack engine parts from a 1971 Charger.

They include the following:

  • The 1970 and 1971 pistons have four valve reliefs in the top of the flat piston. 1969 has flat top with no reliefs.
  • The compression ratio is 10.1:1 for 1969*, 10.5:1 for 1970 and 10.3:1 for 1971.
  • The top piston ring is chrome molly.
  • The valve stems are chrome.
  • The valve springs are Hemi valve springs.
  • The camshaft is low-taper enabling some rotation of the lifters in their bores. Although the cam has the same specs as a regular 440.
  • The valve lifters are the same as a 440 except .0005″ under sized and flat faced.

Other non visible differences is the rocker arms were the same as a 440 but stamped from heavier gauge steel.

The crankshaft was the same as a 440 but was shot peened.

* There is some literature indicating the 1969 pistons and compression ratio are 10.5:1 with the valve reliefs. This literature includes Willem Weertman’s (Chrysler Chief Engineer) book and some magazines from 1969. There is other evidence indicating the 1969 engine had the same pistons as the high performance 440. This includes 1969 and 1970 road tests done by magazines. It also includes the NHRA engine specifications. These specs were provided to the NHRA by the manufacturer.

Engine was Pulled Out of a V or M Code Car

For this identification method to be efficient, you have to be 100% certain the engine was pulled out of an original V or M code car.

The partial vin on the block has to match the vin from the verified V or M code car. There should be documentation about the car, especially if it was sent to the crusher years ago.

My friend used to know somebody who was the original owner of a 1970 V code Roadrunner. The car was wrecked, the engine was pulled out and unfortunately the car was sent to the crusher.

This occurred way back in 1972 before anybody could see into the future. This would not happen today.

Anyway, the owner of the car retained the engine and all of the documentation about the car. This included the window sticker, sales invoice and broadcast sheet containing the vin of the car.

In 1985 I went to a garage where a gentleman was selling a 440 engine which he claimed was an original Six Pack. He couldn’t provide proof of the engine’s origin so I passed on it. Looking back maybe I should have bought it anyway.

How to Eliminate it as a 440 Six Pack Engine

Certain clues to an engine can easily eliminate it as an original six barrel engine.

Casting Date

An obvious one is the casting dates on the block. If it indicates anything other than 1969, 1970 or 1971, it’s not a Six Pack engine. Except for the few that snuck out of the factory in 1972.

If you’re interested about those few 1972’s, you can read about it in my article, Cars With a 440 Six Pack From the Factory.

ID Pad

Another is the letter on the engine’s ID pad. It should be one of the following three letters following by 440:

  • E 440: 1969 block
  • F 440: 1970 block
  • G 440: 1971 block

Any other letter, it’s not an original engine. Remember, just because the pad might have one of these three letters doesn’t mean it’s a 6-BBL engine.

Partial Vin

Only for 1969, the partial vin on an original engine should have the letter A. This is because all A12 cars were assembled at Lynch Road.

If somebody claims it’s a 1969 and the partial vin has another letter other than A, it’s not an original 1969 6 Pack engine.


If someone is claiming the engine is a 1969, the balancer won’t have the external balanced one with the eccentric balancing ring. The ’69 engine has the same balancer as a regular 440.

If someone is claiming the block is a 1970 or 1971, all HP 440s, 6-BBL or not, will have the same balancer. It will have the eccentric balancing ring.

Keep in mind the balancer, and the internals may have been changed over the years.

Find out how much 440 Six Pack cars are worth including A12 cars in my article, How Much an Original 440 Six Pack Car is Worth: Recent Prices.

Wrapping Up

Remember, many engines have been changed and modified over the years. Not everything is what it seems to be.

Many hot rodders in the ’70’s installed factory Six Pack intakes and carburetors on their 440 HP engines.

Finding aged carburetors and intakes on old engines may look like the real deal but often isn’t.

The best way is to match the partial vin on the block to a vin of an original V or M code car.

Find out how fast the V and M code models were in the 1/4 mile in my article, How Fast is a 440 Six Pack or 6-BBL? 1/4 Mile and 0-60 Results.

1969 Plymouth Road Runner 440 6 BBL.

What a 440 Six Pack Engine is Worth

440 Six Pack or 6-BBL Specs

440 Six Pack Horsepower and Torque – Rated and Real HP

What a Six Pack is on a 440 Mopar Engine

440 Six Pack Firing Order

Any questions or if you have more information you’d like to contribute, send us an email found on our contact page.

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