I am making this thread to assist those who, like me, are or at least were at some point trying to find and identify a 240 or 300 head for whatever reason. In my case, I wanted a 240 head to install on a 300 block for the higher compression.

Hopefully, when Googled, this thread will show up for people. I found it harder than necessary to find a conclusive answer on the differences between the two. I know the information is out there, but it is scattered all over the place. I'd like to bring it all here in one spot to make it easier for anyone trying to learn.

There isn't much in terms of physical differentiation between the two. Here is a collection of what little differences there are.

All information is for North American vehicles.

If an error is spotted or further information is revealed, please let me know and I will add it to the list. I want to make this as easy as possible for anyone researching. I don't want them to be scrolling through pages of this thread to get their information.

Casting numbers.

The casting number can be found at the front of the head, on the bottom, underneath the thermostat, offset toward the driver's side. Like any Ford part, it will start with a letter and then a number.

The letter represents the decade and the number represents the specific year.

Example: C9

B = 1950
C = 1960
D = 1970
E = 1980
F = 1990

Adding the number, we can conclude that a C9 casting was from 1969.

It can be noted that Ford used this date coding system on pretty well every part they made.

After the date stamp, the next two letters are important. It will either be AE or TE.

Example: C9AE

AE = Automotive Engine
TE = Truck Engine

Ford was notorious for not being consistent with their casting numbers, so I can give no definitive answer. I can only say what things should be. If the head has AE, it is highly likely to be a 240. If the head has TE, it should be a 300.

Any proceeding numbers after the first four are irrelevant.

Availability.

The 240 was used in full size cars from 1965 to 1972, and up to 1974 for fleet vehicles. In trucks and vans, it was used from 1963 to 1974.

The 300 was used in F-series trucks and E-series vans from 1965 to 1996, but in 1987 the 300 was converted to fuel injection, which used a different head.

Valvetrain.

Valves, seals, springs, retainers, rockers, and anything else related to the valvetrain is all interchangeable.

Physical characteristics.

The spark plugs are on the driver's side and the intake and exhaust are on the passenger side.

The head dimensions (LxWxH) are 29 1/8" x 6 3/16" x 3 3/4". The height measurement does not include the rocker pedestals.

Block Differences.

If the head is still on the engine, it is honestly impossible to know for absolute certainty whether or not the head is a 240 or 300 head. All these clues can lead you to believe that it is one or the other, but thanks to Ford's lack of proper casting identification, it is impossible to know for sure.

For further evidence, however, we can look at the block. Its casting number will also be an AE or TE. This casting number is located on the passenger side, down low near the oil pan, and rearward by the starter. Again, AE likely means 240 and TE should be a 300, but Ford often used whatever blocks they had on hand on engines where the stroke was the only difference, such as their "big block six".

So, to know for sure what displacement the block is, we can pull a spark plug, stick a piece of wire down in the cylinder, and measure the stroke by rotating the engine.

The 240's stroke is 3.18" and the 300's is 3.98".

Combustion chamber.

A 300's combustion chamber measures 76cc and the 240's measures 68cc.

The combustion chamber is the biggest difference between the two. Excluding the casting number, it is the only difference. If you have the head on the engine, you can only be hopeful that you have the head you want. If you have the head off the engine, you can instantly know what head you have.

The 300 chamber looks like a D, and the 240 chamber looks like a kidney bean.

Note the difference?

300:



240:

 

Some corrections.

The 240 was available in full size cars from 65-72. And Full size trucks and vans from 65-74.

And the carbed 300's CC size is 76cc.

 

Corrections made. Thank you.

 

Bump for visibility. It would be great to have this stickied.

 

In addition to the differences you listed there other year-to-year differences in the various heads produced:

- There are two kinds of pushrod clearance holes - a close tolerance pushrod guide slot used on earlier heads to align the rocker arm tip with the valve stem. Later heads with pedastal mount rockers have round drilled holes for pushrod clearance.

- There are at least three kinds of rocker arms used - one with 3/8 studs and a 3/8 NF thread adjustable hold-down nut (these were used with both cast rocker arms or stamped rocker arms); one with 3/8 studs and 5/16 NF non-adjustable nuts, and one with broached pedastal bosses and stamped pedastal style rocker arms and 5/16 NC hold-down bolts.

-The EFI heads have heart-shaped combustion chambers with a masked intake valve to generate fast burn characteristics. They have approximately 69cc chambers. Also, the valve cover and gasket is significantly different to clear the EFI runners.

Other minor differences also exist (e.g., brass core plugs for marine applications, etc.).

 

Thanks, FTF. Would you mind doing a detailed writeup? You obviously know more about that than I do. More details the better. I'll happily include it. I just don't want to say that there were differences. I want to indicate what differences there were during what years and in what vehicles... you get the idea.

I probably won't add anything about the EFI stuff though as during the EFI years that head was alone and it's easy to know when it's an EFI head. I'm mainly trying to point out the differences between the 240 and the 300 during the carbureted years as it seems to be the most confusing.

 

Where did you come up with this malarkey? It's incorrect.

You cannot go by casting, ID engineering or part number prefixes to ID what vehicles the part fits or what year the part was issued.

A casting number prefix could have been used for one year, or for several years.

A does not refer to automotive, it refers to full sized Ford (Galaxie, LTD, Crown Vic and etc).

If you found this casting number on a block: C6ME-6015-AB .. what does the prefix represent?

And just because the casting, ID or part number prefix has a T as the 3rd digit, doesn't mean the part was truck only.

C9, for example is not a date code. Cast parts have a foundry mark on them for the day they were cast, for example 9AB = first week (A) of February (B), 1969 (9).

Casting numbers are foundry marks, cannot be cross referenced to Ford part numbers.

And...FoMoCo is infamous for replacing/updating 10's of 1000's of numbers EVERY YEAR!

 

Bill, I know. I never said you could identify what engine went in what by reading the casting number. Nowhere did I even hint at that. As I explained, there is no easy way to identify the head without looking at the combustion chamber and that the casting number could only lead you toward what it might be. If it was that easy, we wouldn't even have any confusion over which head is which.

C9 is definitely a date code. It means the part was made in 1969. There was no 9AB used on these heads. It would only be C9. Look at the picture of the 240 head at the top. It's a D2AE, or a 240 head from 1972.

It was also clearly indicated that the AE heads were likely to be found in full size Ford cars. The goal of this thread is not to nitpick and what each digit on a casting - or foundry - mark means. The goal is to help people identify one (240) from the other (300).

By the way, C6ME is a Mercury engine part made in '66.

 

The C9 isn't the date code. It's the year that engineering version of the part was first produced. The parts were used multiple years with the same casting #'s. The casting # will give you a general idea of the age. Like if your head says C9AE then 69 is the oldest the head could be. But it could also be a 70 or 71. You have to check the date code to know the exact year of the head.


The actual date code is either after the casting # ( on the other side of the head under the thermostat housing ) or under the valve cover area. I don't remember which area for sure. It's been a long time since I was concerned about the exact year of a 240/300 head.

 

Bump to put this back on top as I see in some other threads that there is still some confusion over the differences. Moderators seem to have disregarded my request at a sticky. OP can no longer be edited it seems so I hope that no more errors are found.

 

trozei, Your attempt to distinguish between the 240 head casting (68cc nominal chamber, kidney bean shape) and the 300 head (76 cc nominal chamber, D-shape) is underappreciated. Your comment that a xxAx casting is a 240 casting and a xxTx casting is a 300 is correct. That is all anybody needing to differentiate between the two needs to know.

FTF

 

Thanks, French. I was just annoyed at how scattered the information around the 'net was when I was searching for a 240 head. I wanted to make things easier on anyone else.

 

there is also the light duty 300. this uses a 240 head the heavy duty is the regular 300 i have a 76 ford and it hade problems cause the guy that had it put the light duty spark plugs in it. and the engine will have the emissions tag on the valve cover.

thank you

 

This is the first time I've heard of a 300 with a 240 head from the factory.

 

I do not think so.