Heads khk

[fabkh55]

Hi ! I m Fabio i live in Italy and I have a little Harley garage …I m currently restoring a 55’kh and 56khk …so inside of the khk I found a kk cams unfortunatel and I wanted to know if there was a way to recognize the codes of the heads, to find out if they are the originals


Thanks

[starcain]

KK cams are the same as KHK cams. Some cams are stamped KHK, others are simply stamped 1,2,3,4. The numbered cams are KK and when the KHK was introduced they started stamping them KHK. It is believed that many numbered cams were used on the KHK's to use up the KK cam inventory. Bottom line, they are identical cams.

There is no known code to designate KHK heads from KH heads, at least that I am aware of. KHK heads were polished to a mirror finish while KH heads were not. If you get them good and cleaned up, you should be able to tell if they are polished or not.

Stan

[Simon]

There are no markings as Stan mentions, however if I recall, you may see round reliefs fly cut into the combustion chamber to allow valve clearance due to the higher-lift cams.

[wz507]

There are no markings as Stan mentions, however if I recall, you may see round reliefs fly cut into the combustion chamber to allow valve clearance due to the higher-lift cams.

There were 2 different relief types used to provide valve clearance in K Model combustion chambers. I can’t say for certain the chronology of these changes, but believe the “Spot” machining Simon referred to was the earliest version and the fully machined version was the final iteration. The image below shows 3 different stock K/KH combustion chambers – stock unmachined (left, earliest version), spotted (middle, intermediate version), and fully machined (right, final version).

LR K Heads - unmachined, spotted and fully machined.jpg (130.63 KiB) Viewed 61347 times

All chambers as delivered were more than adequate to accommodate the stock KK/KHK valve lift of 0.3815”. However, valve to head clearance was close as shown in the image of the unmachined chamber below.
Note the small radial “smile” at the tip of the red arrow where a floating IN valve has contacted the chamber roof in the step-up between the IN valve and the EX valve pockets. I have observed this same “smile” on several unmachined combustion chambers.

Stock early K head with IN valve contact.jpg (252.9 KiB) Viewed 61347 times

This area of contact was machined out of the way in both the “spotted” and “fully machined” chambers. In the cased of the spotted chamber the IN valve relief was enlarged to avoid contact in this area, and in the fully machined chamber, milling has deepened the IN valve relief in an even larger area, and hand work has occurred along the step-up between IN valve pocket and EX valve pocket to provide an even larger relief. Note that in the fully machined chamber the milling operation covered the entire IN and EX valve pockets and ends in a “square” edge at the roof the chamber.

In earlier posts reference was made to KHK heads being polished, and related to that subject is the image below of 2 NOS KHK heads. Note that polishing was only on the extreme right and left ends of the heads and that the mid-section was untouched and remained as cast, i.e., unpolished.

NOS KHK Head Polishing.jpg (193.41 KiB) Viewed 61347 times

A lengthy earlier discussion (6+ pages) covering many nuances of K Model heads can be found on this forum at the link below.

viewtopic.php?f=3&t=601

[Simon]

Thanks WZ507 for your in-depth reply - that's new info to me, and as such greatly appreciated!
I wonder if later KR grinds needed even further relief, or if in fact the KR heads themselves were fully relieved to match these iterations, similar to the later head in your pics? Will have to re-check mine at next opportunity...

[EKHKHK56]

Hi, a couple thoughts on K heads. The heads can’t just clear the open valves, the clearances are set for flow. The 4 basic head types for Ks are:1- 52-53 with rough type castings and relieved numbers. 53 KK would have KHK chambers as they use same cams and valve head diameter. The valves require spacing above open valve of .125” Intake and .080” Exhaust for Flow. Plus or Minus .020”. Correct as needed. 2-KH 54-57 finer type casting with raised part numbers. About 60 KHs were produced in 57. 3-KHK 54-56 Same as KH but chambers to match KHK cams and spacing above open valves. More relieving in shelf and around valve pocket. 4-KR heads have many versions, basically the “Ice Cream Cone” style combustion chamber helped the gasses make the 174 degree turn from port to bore. That slight tipping of the valves on Ks did help flow enough to warrant implementation. Chambers were relieved around valve head for larger KR valves, and for flow space above the open valves. .395” lift cams used .090” above intake and .060” above open exhaust plus or minus .020” .420” cams such as E set use .070” above open intake and .040” above exhaust. You can easily customize cam lift by machining the base circle, backside. What is removed translates into that much more lift. With the sturdy roller tappet it works fine. .420” is about the limit. These E 420 cams I have open intake valves at 70* BTDC. Amazingly idle quality is fine and sounds great. Factory chambers were smooth and polished in entirety. The heads with the Flycuts were done by brazing 3 cutting bits to the head of a valve as per H-D Shop Dope recommendation for privateer to self relieve heads above the open valve and adjust clearance for flow, depending on cams and valves. So I believe the center head posted is a clearance attempt outside factory and unfinished. Other heads with impressions similar but very shallow result from valvetrain failure such as spring, keepers or stem. The clearances above open valves were provided to me by Marsh Runyon, Joe Leonard’s Buddy and Tuner for 54,56 & 57 AMA National Championships. They probably don’t match the Book. Tom Sifton sponsored the effort with his experimental cams an added bonus. Tuning each cylinder as a separate engine provided better throttle response and stronger smoother torque. The idea is to compensate for the 45* V twin’s difference in intake charges between cylinders. With equal cams, one pulls more charge due to piston dwell times during the intake event. Erik

[wz507]

So I believe the center head posted is a clearance attempt outside factory and unfinished. Erik

If I am interpreting the quoted comment correctly, I believe it suggests that the middle image presented by me above is the unfinished work of a privateer. I want to nip this in the bud and dispel any notion that the “spotted” head is anything other than a factory head. I’ve seen dozens of these factory spotted heads, and have an NOS set of KHK heads that show this exact same factory relief. The NIB NOS heads referenced are shown below, and are the variant with the sparkplug hole fully encircled by fins. The machining is very minimal in the EX pocket where the tooling has barely cleaned the cast surface, but deeper and more extensive in the IN pocket where circumferential valve clearance is required at the step-up between pockets. Modest factory hand sanding was performed on both heads to blend the machined surface to the cast surface.

LR NOS KHK Head Combustion Chambers.jpg (137.23 KiB) Viewed 61281 times

LR NOS KHK Heads top view.jpg (213.89 KiB) Viewed 61281 times

LR NOS KHK Head and Box.jpg (267.65 KiB) Viewed 61281 times

[EKHKHK56]

I don’t know who machined what when. I meant that to be a question. All KHK heads started as KH I think. So machining and hand blending are necessary regardless. Production bikes would never have heads partly blended and unpolished. I have a few like this, some with only one pocket relieved. Yours appear to be shaved, see the deck broaching is not perfect smooth factory looking to me. With no head gasket the surface should be perfect.The service bulletin from H-D shows how to make your own cutters, for dealers and privateers to set the clearance above open valves when needed. Every complete KHK engine I have owned had heads with 100% smooth chambers and decks. Is it possible the heads are NOS KH with box but reworked by owner? Do they say KHK on box, or part number 16682-54 & 16685-54. Just curious. They appear to be decked which would be wrong. Easily checked. Flow not Compression is what makes these flatheads run. Compression boosts hurt flow. Just ask my Buddy Anders at Swedens Flathead Power. 5.99 to 1 is what Len Andres of SoCal determined is max compression for his best developed KR engines as a rule. This was when the Factory rewarded each dealer developed HP with a 1,000$ check. Per HP. At least in 1954. All KHK heads had to be built from KH ones, so perhaps H-D sold them machined but not finished. I have no idea, totally possible as all were hand worked in the end. I had 20 some engines/bikes/projects at one point along with several loose heads that a few had pockets cut, with no blending or only one pocket. Some were NOS KH, totally unpolished. KHs had side fins polished like KHK stock on production bikes starting in 1955 so that polishing is not a identifier for KHK only. 1955 New Model Announcement. Sept 1954. I don’t know much about Ks but learning is ongoing and each day brings more hope. From experience we know some K facts can be hard to pin down, especially if people have intervened during the last 70 years. Very interesting, thank you for posting those. Erik

[starcain]

Here are a couple pictures of the heads that are on my OP '56 KHK. They have about 35,000 miles on them. They look a lot different than wz507's NOS heads? For what it's worth, I talked to a friend that also had a set of NOS KHK heads years ago and he remembers them as having been polished across the combustion chamber as well as the valve area like mine are as well as the picture of the KHK head out of the 1956 Enthusiast announcement issue that I posted earlier.

Looking forward to hearing any thoughts you guys might have.

Stan

[EKHKHK56]

Hi Stan, those look good. The same September 1954 New Model Enthusiast clearly states “in special KHK Again available in 1955” “In this model intake and exhaust ports as well as cylinder heads are polished to a Mirror finish” As in complete combustion chamber and outside fins mirror polished. That’s also one more 1954 KHK legitimization clue besides Spare Parts 54-56 KHK parts listed as such. I haven’t noticed much other publishing about the 1954 KHK with unpolished side fins. 30 years ago some people asked about the proof of the 1954 KHK’s existence and I couldn’t find much except in parts listings of heads, cylinders, cam sets, etc. Interestingly the 53 KK and 56 KHK used the 53KR tappet assemblies. Looks like the 54 and 55 had different ones, but same Cam Set. Back to the heads yes mirror polished combustion chambers. Does anyone have any other 1954 KHK model literature? Same for 53 KK, haven’t seen much beyond parts books. First versions used 41 WR valve setup with the Cowboy Boot tappets. Onward we go into the K model mystery. Did you know you could buy a new Sportster in 1954 for $13.95? Jacket that is… Erik