Does anyone know the actual difference in the combustion chamber volumes of the 240 and 300? I want to do a comparison of compression ratios using different components. I need the numbers to do the math. Thanks.

 

I believe the 240 head has 68 cc chambers, the 300 carb head has 76 cc chambers. I think the 300 EFI heads are similar in size to the 240, but not sure of the exact size.

 

You get about a .5 bump in CR with the 240 heads on a 300.

 

Thanks you. I've been hearing that," .5 bump" and I believe it. I am just looking to do the math myself and confirm it. There should be a source of the actual combustion chamber volumes of each type of head. For example, I suspect the EFI heads are different in volume than early 300 induction heads and those should be different from a 240 as well.

This information is easy to find for FE bg blocks, but I haven't found it for our I-6s. Anyone else have the "actual values"?

 

F100Jim,
Missed your post on my last reply. I will use those numbers for now until someone comes up with a more definitive answer. In most "cast" heads volume was given in a range to account for minor variations (I guess). For example an FE head w/ casting number C6AED is 71.2-74.2.

I can find that info in Steve Christ's book Big-Block Ford Engines. I don't have a good source for the same information on the I-6s. Thank you.

 

EFI heads are not much different in volume but the shape of the chamber is a little different.

 

S'up, Harte! Seems like last time you and I talked we were razzing each other about Eastern Wash. hicks and big city whatevers; no idea what the topic was.

F250Restorer was kind enough to post photos of these heads on a thread of mine, "240/300 Ford Big Six," which is currently on page 2. He also told me something valuable that I had not heard on FSP, that the EFI heads have some tendency to crack, unlike the 300 smog heads or the 240 heads. With their enhanced swirl, the EFI heads should be the choice for a torquer, but not if they crack.

 

Hey Smitty! Friendly banter I am sure!

The EFI head cracking problem has been floating around for some time and raises it's head on occasion.