Simon wrote: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 61573 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 61573 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 61573 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