Heads Up – K Model Head Quandary?

Production K Models

Re: Heads Up – K Model Head Quandary?

Postby wz507 » Mon May 01, 2017 6:35 pm

LDB wrote:Thanks for your reply, wz507. So if all cylinder heads were not cast parallel to the gasket surface then that means the round quench area recess above the piston must be at an angle?

Only the combustion chamber area immediately above the valves is angled at the same complimentary angle as the valves. The quench area over the piston is flat as a pancake and parallel with the gasket surface.

LDB wrote:I can see how there might be some benefit if the recess above the valves were tilted toward the cylinder bore, but both valves tilted one way to the side makes no sense to me unless the valve is at such an angle that it would hit the head if a matching slant was not maintained in the head. That would have to be quite a slant of the valves.

As I noted previously, the angle of the intake valve is such that for the 1.800" dia IN valve the difference in height, relative to the gasket surface, across the valve face (measured at points A and B on the valve head) is ~ 0.100" (trigs out to an angle of ~ 3.2deg), so yes there is a very substantial difference from side to side and yes a flat chamber in this area would result in 0.100" clearance above the valve on one side of the valve head and 0 clearance on the other side. I assume the unusual sideways angles of the valves are the result of a design intended to create as compact a combustion chamber as possible in light of the location of the cams in the case. Without the valve angularity the alignment of the valve train would be far worse. In this unusual K valve train the lifter bores are tipped toward the cylinders (IN and EX each set at different angles) and the cams are ground at these same complimentary lifter block angles too. If you look carefully at the image of the KHK cam lobe below you can see that the lobe face tapers towards you (is smallest near you) and is larger on the rear perimeter as you view it. Just more of the peculiar K model allure. Wish I had a side view of a cam lobe which shows the angle even clearer, but alas no side view.

KHK cam grind angle.jpg
KHK cam grind angle.jpg (117.35 KiB) Viewed 14212 times

LDB wrote:Have you ever measured a clean head that has not been touched in the valve area to confirm they are at an angle or have all the ones you've measured but cut deeper with the milled circles to one depth or another? Thanks.

Yes, head #1 in the study above is an unmolested as cast cylinder head, and has the same angles as the other 2 heads in the study. The machining does not change any angle, just deepens or widens the existing combustion chamber surface.
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Re: Heads Up – K Model Head Quandary?

Postby starcain » Tue May 02, 2017 11:48 am

wz507, I happened to have some stuff around to make up a cam holder to get that side view of the cam you were after. The straight on shot is just to show that it is the same #1 KK/KHK cam that you have pictured. The side view clearly shows the amount of tapper that the cam lobe grind has. Hope this is what you were after.
Stan
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KK Cam.jpg
KK Cam.jpg (152.9 KiB) Viewed 14200 times
KK Cam Side View.jpg
KK Cam Side View.jpg (100.11 KiB) Viewed 14200 times
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Re: Heads Up – K Model Head Quandary?

Postby EKHKHK56 » Tue May 02, 2017 12:04 pm

The Valves are tipped because significant flow increase was realized with minimal tipping. The book must be wrong, surprise! listing the 52 early head for KH through 56. Just didn't happen. The larger chamber KH head was different and had the weak raised number style and probably the clear raised number by 55.
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Re: Heads Up – K Model Head Quandary?

Postby wz507 » Tue May 02, 2017 12:14 pm

starcain wrote:wz507, I happened to have some stuff around to make up a cam holder to get that side view of the cam you were after. The straight on shot is just to show that it is the same #1 KK/KHK cam that you have pictured. The side view clearly shows the amount of tapper that the cam lobe grind has. Hope this is what you were after.
Stan

Perfect! Thanks Stan.
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Re: Heads Up – K Model Head Quandary?

Postby wz507 » Sun Jun 25, 2017 6:09 pm

The gods of K model heads looked favorably upon me recently as I came across a head I’ve not seen before, mind you I’ve handled less than 10 total heads in my life. Anyway, was visiting some local friends a couple days ago and the conversation turned to K model heads. They informed that they’d recently sold a KK engine to someone and that only a 53K engine remained to dispose of. I asked if they’d ever looked at the heads and the reply was no. So we started peaking under the head to see if we could observe the casting number and my friend said here it is. However the location he pointed to is not where the K model head casting numbers typically are. I took a peak and was quite certain I saw the number end in a -52R. Bingo, since some of the R heads were numbered in a different location so I figured we were into a set of 52R heads.

Although I thought it would be a long shot I inquired as to whether we might be able to remove the heads for a peek, and before I could gather myself a ratchet with 9/16” socket was placed in my hand with the comment “do whatever you want with them”. Yippee!

So, heads were removed, cleaned and photographed to add to our archive here. Interesting to note that it appears some piston ring debris has circulated through one of the combustion chambers as evidenced by all the nicks in one of the combustion chambers, and the other head appears to have ingested a 1/4-20 carb bolt somewhere along the line as evidenced by the "thread tattoo" in the combustion chamber .

I also made castings of the combustion chambers as I doubt I’ll ever have such ready access to these items again. Since I’m building a 56 K and was intending to perform some airflow testing on the cylinder/head assemblies as they near completion, thought it would be nice to have these combustion chamber castings since I could make epoxy castings of them and use these epoxy heads as a means to easily modify the combustion chamber, without carving up a real head, to determine what if any differences in airflow result from said modification.

If by any chance somebody might be in possession of a -60R or -69R cylinder head that they would consider lending out for a very brief period of time I would love to get a casting of these heads. Of course I'd reimburse shipping both ways and would need it for perhaps 3 days maximum to assure I got a good casting. Thank you.

Because the forum limits us to 3 images per post I’ll use this and several subsequent posts to show the images of these heads.

PS - these heads have no additional number stamped on them anywhere to indicate the particular iteration, e.g., integers from 1 to 7

Nice set of matching snowcones here
CC of -52R from valve side.jpg
CC of -52R from valve side.jpg (122.09 KiB) Viewed 14011 times


Early coarse discontinuous fins
Top view of -52R heads.jpg
Top view of -52R heads.jpg (64.61 KiB) Viewed 14011 times


Tall window between upper and lower deck
-52R window height.jpg
-52R window height.jpg (69.56 KiB) Viewed 14011 times
Last edited by wz507 on Sun Jun 25, 2017 10:15 pm, edited 3 times in total.
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Re: Heads Up – K Model Head Quandary?

Postby wz507 » Sun Jun 25, 2017 6:16 pm

Below are images of the combustion chamber casting process, the castings themselves and a detailed image of a single combustion chamber casting.

Casting process
-52R CC casting process.jpg
-52R CC casting process.jpg (71.75 KiB) Viewed 14011 times


Snowcone mirror images
-52 R heads with CC castings.jpg
-52 R heads with CC castings.jpg (151.36 KiB) Viewed 14011 times


Single combustion chamber with ingested bolt witness mark in the squish area
-52R CC casting.jpg
-52R CC casting.jpg (58.75 KiB) Viewed 14011 times
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Re: Heads Up – K Model Head Quandary?

Postby wz507 » Sun Jun 25, 2017 6:27 pm

In previous discussions in this thread LDB posed questions regarding the sideways “tilt/cant” of the valves in the cylinder. In an attempt to illustrate this I placed one of the -52R combustion chamber castings on a sheet of ¼” thick glass and positioned the camera slightly above the plane of the glass. This image clearly shows that the combustion chamber compliments the canted angle of the IN and EX valves as the chamber over both valves tilts downward toward the rear cylinder.

x-section of -52R head.jpg
x-section of -52R head.jpg (65.83 KiB) Viewed 14010 times
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Re: Heads Up – K Model Head Quandary?

Postby wz507 » Sun Jun 25, 2017 8:56 pm

I started this topic to gain a better understanding of the K model heads available from the MoCo, and specifically to determine what the correct heads might be for my 56 KHK. The initial post in this topic provides part numbers for the various year fitments and suggests that there were basically 2 head sets available - early and late. The early heads were for all years and models of Ks with the exception of the KHKs. The late heads were for all years of KHK. Sounds simple doesn’t it, there are only early and late heads, so how hard can it be to determine the correct heads for a project?

As I saw more K model heads, and received additional input to this topic from forum members here the task of determining a correct head got perpetually more difficult for me. At this juncture I believe you could literally machine the combustion chamber of any head you find to fit your specific K model and it would be correct. Consider the following table showing the variations we’ve uncovered since starting this topic.

Table 1 - Head Casting Variations.jpg
Table 1 - Head Casting Variations.jpg (36.75 KiB) Viewed 14002 times

The table clearly illustrates that the late head could be either tall or short window, could have continuous or discontinuous fins, and neglecting the form of the combustion chamber for the moment, on a bike would be indistinguishable from the early head and vice versa. As I continue examining images of K model bikes I see a real hodge-podge of mismatched heads on them (several here in the Forum gallery), e.g., I’ve seen a tall window head on one cylinder and a short window head on the other cylinder, and similarly a continuous fin pattern on one cylinder and a discontinuous fin pattern on other cylinder. Since the early and late heads can’t really be distinguished by any external feature (other than inspecting for a casting number), it is my opinion that literally any head fitted to any K model could be correct. I’ve heard no evidence to the contrary and given the running changes that seemed to occur perpetually, the significant variations that occurred across a given casting number (per details in table above), the fact that the parts book is in error (KK and KHK are same cam so need same valve to head clearance, yet parts book uses different cylinder head part #’s for these applications) it’s just very difficult to say what a correct head is for almost any of the K models, especially the later ones.

I don’t mean to imply I know anything at all about the subject of K model heads because I’m a newbie and I know that I don’t know, in spite of it being a well-known fact that you don’t know what you don’t know! However, you’ve got to start somewhere so thought it better to get my thoughts in the written record than to leave them off in the ether somewhere.

So, now it’s your turn. What would be especially useful at this juncture is to receive additional input from the forum members that have many heads to scrutinize, e.g., guys like Erik H who have 30+ heads could no doubt provide additional information that might expand our understanding by contradicting or reinforcing the comments and table data above. Erik has already suggested that an early head exists that has a relatively rough appearing casting number (which I have not observed) and we don’t know where this fits into the mix. So here is a call-out to all K model head owners out there, please look over your stock and see if it is consistent or contradictory with the above comments and table information. By sharing this information our mutual understanding of the topic will be enhanced. Thank you.
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Re: Heads Up – K Model Head Quandary?

Postby LDB » Sun Jun 25, 2017 10:56 pm

Wz507:

Do you think maybe that you could measure the thickness of your epoxy castings at various places and post it? The picture of the exhaust side looks like it's real thick and tapers towards the shelf and the picture of the intake side looks like it's thinner and gets thicker toward the shelf, or left to right in the picture. Does the epoxy you used have any shrinkage that would make it smaller after it sets up and dries? Thanks.
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Re: Heads Up – K Model Head Quandary?

Postby wz507 » Mon Jun 26, 2017 2:01 am

LDB wrote:Wz507:

Do you think maybe that you could measure the thickness of your epoxy castings at various places and post it? The picture of the exhaust side looks like it's real thick and tapers towards the shelf and the picture of the intake side looks like it's thinner and gets thicker toward the shelf, or left to right in the picture. Does the epoxy you used have any shrinkage that would make it smaller after it sets up and dries? Thanks.

The material I used for casting is a highly filled RTV silicone, Dow Corning Silastic J and the shrinkage is reported to be “nil”. If it is thermally cured the shrinkage then increases to 0.3%. I did not thermally cure it, but had I done that, 0.3% on a thickness of 0.500” is 0.0015”, so not really a consideration for this discussion.

Because the valves tip in 2 planes simultaneously, i.e., the front cylinder valves tip toward the rear cylinder and they also tip toward the bore, measurements are a bit tricky to make since the thickness of the chamber changes significantly with any small change in any direction. That said I attempted to give you a flavor of the chamber thickness at several locations in the image below.

You have a good eye, and yes you are correct, the EX side tapers thinner going to the shelf area. The IN side is a little more dicy to describe because as noted above it makes a huge difference where exactly you are measuring and comparing. If you look at the top view images of the front head combustion chamber, in previous images, you can see a crack that runs across the sparkplug hole and in a sense delineates the head of the snow cone from the cup. Measurements taken at the extreme ends of this crack provide maximum and minimum thickness of 0.490” and 0.393” respectively. The thickness at the tip of the snow cone cup is ~ 0.471”. So depending on where you start, the trough gets slightly thinner heading to the tip of the snow cone cup or it gets considerably thicker.

I also included one additional image that was taken looking straight down the snow cone from the snow end to the tip of the cup, where the sparkplug stub dissects the cup tip. This image is intended to show the difference in thickness from the high side to low side of the IN valve pocket and show that the entire roof plane is canted throughout it's run. I wish all these crazy angles, sloping planes, etc were easier to verbalize and provide images of, but it is challenging to say the least. Hope I've addressed your questions.

CC casting with dimensions.jpg
CC casting with dimensions.jpg (21.86 KiB) Viewed 13986 times


View down snowcone.jpg
View down snowcone.jpg (69.09 KiB) Viewed 13986 times
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