L10 Change on 65 HiPo Head

xirtam67 · April 8, 2010 at 9:58 AM

In the Mustang and Ford Small Block V8 book by Mr. Mannel there are references made to changes L10 and L11 on the 289 non HiPo head in 65 but the changes were not incorporated in the HiPo head till 66.

I have a set of heads, C5OE, F52 that appear to have those changes incorporated. I have seen examples of just the guide slots being machined, but I believe the changes on these heads are factory changes because of the additional circumference change to allow use of the smaller valve spring and the valve guide casting configuration is the later form.

Has there been cases of this early incorpaoration?

bobmannel · April 17, 2010 at 10:29 PM

So far, it appears that 1966 289 HiPos were L9 engines, and 1967 289 HiPos were L13 and L14 engines. (L5, L6, L7, and L8 apply to 1965 289 HiPo engines.) However, L13 does not mean that L10 (small valve springs), or L11 (rail rockers/round holes on Windsor engines), or L12 (rail rockers/round holes on Cleveland engines) were encorporated. 1967 began with L13, and L14 replaced the smaller valve springs with larger ones, which was not applicable to the 289 HiPo. In summary, I don't know of any 289 HiPo engine tags with L10, L11, L12, or L15 (emissions driven changes). If there are, I would be interested in hearing about it.

Participate now!