808mopar

Hi,
Did Dodge change the head runner size on 1975 225 Slant Six?
Thanks

Kuvasz101

They did change the head design in 75 or 76. The way to tell is the newer design had small (peanut plugs). The older design has larger plugs that have the metal inserts that go inside the head with an O ring around the insert with the spark plug going inside it. The newer engine actually was built a little less beefy or sturdy than the older design but still a very good engine.The older design had wider connecting rod bearings.

808mopar

Thank you for the tip identifying the two heads.

Iowan

I’m not sure but the bearings are narrower but the rods the same, I believe change’s were made to increase fuel mileage or to make the bean counters happy. A few times I’ve read up on the /6 heads I haven’t seen a good 225 head or a bad one. I know chamber sizes changed over the years with engine size.

Kuvasz101

One important note if using the stock exhaust manifolds. There's a clamp that secures the exhaust pipe (located about a foot downstream from the header exhaust flange) that attaches to the engine. If this clamp is missing, broken or neglected the weight of the exhaust will always break or crack the exhaust manifold.