In a previous thread on K Model heads, images and casting numbers were presented for the various heads I had in my possession at the time. Others contributing to that topic offered concrete evidence that there were more castings than the 2 early and late series I had in my possession. A while back I visited a friend and saw a late style casting that looked unusual, or at least very different than the late style castings I had. We recently got together and compared the heads in our possession and observed a difference that created a quandary for me – mind you it takes very little to create a quandary in this feeble mind - so to that end I started a new topic here to describe the quandary/anomaly.
In the previous thread the following was reported regarding the head part numbers and casting numbers.
Early Front Head Casting Number
16682-52, with numeral 1 underscore, label appears as negative on casting
Early Rear Head Casting Number
16684-52, with numeral 1 underscore, label appears as negative on casting
Late Front Head Casting Number
16682-52, with encircled E underscore, label appears as positive on casting
Late Rear Head Casting Number
16684-52, with encircled E underscore, label appears as positive on casting
In a cam discussion elsewhere on this forum it was suggested that the KK and KHK cams were the same, yet the above parts fitment description from the ‘52-56 Spare Parts manual suggests the KK and KHK had different heads? So the parts book would leads us to believe that the early head was suitable for all cam lifts - low (K), medium (KH), and high (KK), yet the KHK head is listed as a separate application so how did the KHK head differ from these others?
Rightly or wrongly I assumed the casting numbers above simply referred to the 2 different casting types, - the early and late, with the early being for low lift cams and the late being for high lift cams, yet the fitment data is certainly at odds with this thought process. The primary external features distinguishing the early and late heads are the following, which are shown pictorially below.
1. The “window height” between the upper and lower planes of the head on the shallow side of the head (between the cylinders) differs in that the early head has a tall window and the late head has a shallow window.
2. The fins on the early head are shorter in terms of fore to aft run, whereas the later head has some longer continuous runs of fins.
3. The finning appears, to this observer, to be slightly coarser and wider on the early heads whereas on the later heads the finning is narrower and the head in general has a smoother finish.
So now for the quandary. I assumed the early and late heads were 2 distinctly different castings that differed as described above. That is, until I saw the late style head at my friend’s house yesterday - a “circle E” casting, but with all other features of the early casting. See the pictures below of an early head (left) and the 2 late style “circle E” castings (middle and right). The middle head is the anomaly, as it appears to have all the features of the early head – tall window height, discontinuous fins, coarse texture, wider fins - yet it is identified with the late style “circle E” casting ID. Also, the left head combustion chamber is as cast and is shallowest, the middle head has limited machining with valve pocket depth very similar to the right head, and the right head has been milled completely around both valve pockets and might be ever so slightly deeper than the middle head.
In light of the foregoing, please help me understand.
1. Can a single casting number refer to 2 totally different heads like shown above?
2. Did the above occur as the result of some sort of running change during a year or between years?
3. Was the above occurrence a one-time error that occurred in the foundry, i.e., late style casting number applied, but early in all other salient features?
4. Is a short or tall “window height” head proper for any ’54-56 KHK, or for that matter are both the early and late head casting (short and tall window height) correct for any K model of any year?
Look forward to you enthusiasts filling in the rest of the story.