Heads Up – K Model Head Quandary?

Production K Models

Heads Up – K Model Head Quandary?

Postby wz507 » Wed Apr 26, 2017 4:22 pm

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.
K model cylinder head part numbers from 1956 Spares manual.jpg
K model cylinder head part numbers from 1956 Spares manual.jpg (13.5 KiB) Viewed 19277 times

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.
early and late K head castings.jpg
early and late K head castings.jpg (80.92 KiB) Viewed 19277 times

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.
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Re: Heads Up – K Model Head Quandary?

Postby wz507 » Wed Apr 26, 2017 7:21 pm

wz507 wrote: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, coarse or fine fin) correct for any K model of any year?

After looking on line at a variety of K model head images I can address a few of the questions posed above.

1. Can a single casting number refer to 2 totally different heads like shown above? Yes, a single casting number can describe heads that vary in both window height and fin pattern.

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?
No, as noted in my response to question 1, there are numerous examples where the later casting varies in window height, fin pattern etc.

A new question has arisen in my mind regarding the fin pattern. I have now seen a significant number of the late style (circle E) heads that have the early style finning (coarse, thicker fin that is not continuous), whereas the only late style heads I've seen with the smoother finer continuous fins are the ones I own. Perhaps I have it all wrong, and these heads with continuous fins are the odd ducks?

Eager to hear from K owners as to what year bike and model they own, and what the heads look like on their bike.
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Re: Heads Up – K Model Head Quandary?

Postby sportsterpaul » Wed Apr 26, 2017 8:48 pm

My 1952 engine has the earlier fins.

These different heads with the same casting number is a pretty sloppy thing for the factory to do. What it means is the factory designed a new head casting, on a new drawing, with a new casting number. They sent the drawing to the model shop, who made the wooden patterns, but used the old casting number, which is often on a separate wooden block that slides into the pattern. I would guess the head patterns had a rectangular hole where the pattern shop would put in a little filler block with the casting number on it. So then the foundry made new casting with the old casting number, until someone noticed, and then they fixed if by the far right picture you posted.

What I am saying is that there cannot be two different castings with the same number, there are two different drawings in a file cabinet in Milwaukee. What happened is that the Harley pattern shop or the foundry put the old casting number on the new casting, so the number on the part does not match the drawing. In addition to the drawing for the pattern shop and foundry, there is what we used to call a "Make from" drawing at GMC Truck. That would say to start with the casting part number, and then machine it, and put a finish on it. That has a different part number and that finished part number that goes in the parts book.

OK, you rock star experts. Here is the front head on my 1952 K. What is that little screw by the head bolt near the intake manifold. Its only on the front head. Cyl temp? Horn ground?
K-model-front-head.jpg
K-model-front-head.jpg (175.56 KiB) Viewed 19233 times
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Re: Heads Up – K Model Head Quandary?

Postby wz507 » Wed Apr 26, 2017 9:04 pm

sportsterpaul wrote:
OK, you rock star experts. Here is the front head on my 1952 K. What is that little screw by the head bolt near the intake manifold. Its only on the front head. Cyl temp? Horn ground?


Thanks for your comments Paul - certainly sounds reasonable. The screw, 56610-52, along with the clamp, 56609-52, is for mounting the throttle cable to the front head.
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Re: Heads Up – K Model Head Quandary?

Postby sportsterpaul » Wed Apr 26, 2017 10:29 pm

Oh thanks, that makes sense-- I can now figure out the cable routing.
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Re: Heads Up – K Model Head Quandary?

Postby dr dick » Wed Apr 26, 2017 11:42 pm

paul:
your insights you post from professional experience is obviously accurate.
but
you assume, all to often i surmise, that the parameters of 66> company activities, (the kind of thing you relate often to your posts ) correlate to your personal manufacturing experience.
to be honest they probly do.

although to put that (your) mind set on what happened when the moco was still a propitiatory partnership shows you may not be on top of what it takes to fill the bank account with the cash that fills your faithful employees paycheck.
thing are so clear at engineering.,
not so at the sunday family dinner when cash short.


on the shop floor its the same monday.
'what sells isnt what we design________
its what we PRODUCE.
if keeping the production costs reasonable require going back to handshake rather than blueprints, what do you think happened?

for the bikes we consider here:
they are not cookie cutter.
they are like bourbon-- they do start with the same raw material, but how they finish isnt based on paper.
its passion mixed with whats can happen with whats on hand.
so
what happens at the parts counter or the showroom floor is a reflection of the available product.
that very product may have (probly did) gotten there on handshakes.
that tosses a wrench in the works of "historians" as they fact check.

i know your gonna argue with me.
those stepping stones have already been laid.

my insights are nearly extinct.
but my facts are concrete.
have at it.
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Re: Heads Up – K Model Head Quandary?

Postby wz507 » Wed Apr 26, 2017 11:46 pm

Paul, the throttle cable routing should look something like this (stolen from JerryR post on steel gas line in K/sport subject).
Gas line routing.jpg
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Re: Heads Up – K Model Head Quandary?

Postby thefrenchowl » Thu Apr 27, 2017 8:53 am

... I sometimes wish our politicians would put as much effort and dedication as you do on these K subjects to sort out this world!!!

Anyway...

just wanted to say...

The nature itself of sand casting from moulds, cores and patterns, never mind the dexterity of the foundry (and its employees' experience and know how) mean that you will NEVER get the same parts out of the foundry, even when you use the same patterns and employees...

That's one of the reason I love old bikes, they are all unique...

When I was a lot younger, I worked for a while in a foundry making taps... Endless ways to make the castings better, but "overheated 8 litres of wine a day" foundry men near retirement weren't all as bothered as others to do a good job...

Usually 50% rejects that go straight back in the bath.
We were allowed to put more copper bars in the bath, but the supervisor was in charge of the alloy and magnesium ingots, so flowability/quality was better if he was doing his rounds often enough...

In one word, variability...

In 30 years of K, I can only say they can crack quite badly and all the small changes were made either to make them easier to cast or to stop the cracks appearing...

Now, a lot crack and a few don't.

The few that don't crack are probably the ones cast by more knowledgeable guys at Mocasco...

Still, even with these supercasters, I would say a 25% reject rate would be normal...

As a final point, the ones that NEVER crack are the KR ones...

One word of advise, mods all you K or KH heads to KR specs if you wish to do serious mileage with them...

Bye for now

Patrick

PS: The head in the middle of the above photo is a KK or a KHK head and looks factory, The K and KH heads are never machined for inlet clearance by the factory.

Since the KK and the KHK have different diameter inlet valves, it could be that the KK don't require as much work as the KHK head to fit THE SAME early KR grind cam in it
Flat Head Forever
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Re: Heads Up – K Model Head Quandary?

Postby 55panman » Thu Apr 27, 2017 9:39 am

Patrick, You say mod all your K or KH heads to KR specs How do you mod the head to a KR spec? We all know the KR had a cast in bronze spark plug insert and the K's didn't. Do you bore out the K insert, repair weld any crack, then bore and thread hole to accept a (threaded?) bronze spark plug insert? I have repair welded a few K head castings successfully and simply bored and tapped them when done. As I may have said before my technique to weld crack prone castings I got from a friend at Bonneville who worked in the aircraft industry. He told me to heat casting to 350 in an oven and hold for up to 5 hours. I use and old gas barbaQ. Repaired a couple a cracking Pan cases, KR right case that kept cracking. and some Pan heads this way. ANyway, I wish you would expound on how you mod to KR specs.
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Re: Heads Up – K Model Head Quandary?

Postby thefrenchowl » Thu Apr 27, 2017 11:09 am

Leave the spark plug thread alone!!!

Just mod the outside contours where the vertical wall next to valves rise up and meet the top of the combustion chamber at a very sharp angle.

The KR is raduised and relieved there, which reduces drastically the chances of cracks starting up.

Next mod is a bit extreme but I like it: mill out all the horizontal double decker fin, in between the vertical fins.

Image

Image

That DD fin is the root cause of all K head problems...

Patrick
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