k heads

Production K Models

k heads

Postby sean » Sun Nov 30, 2014 10:42 pm

a couple k head questions...
1 . sorting thru my k heads i have.i noticed that they dont match my part book numbers...all 3 sets i have have the same numbers.186682-52 and 186684-52
the part book says 186682-54 and 186681-52 for the front and 186683-52 and 186685-54 for the rear .
the 186684-52 heads i have has a relief cut into the area for the valves and the 186682-52 does not...which valves do i run...book says exhaust valve is the same for all models except kk but the intake differs so which intake should i run with the 186682-52 and 186684-52 heads i have?i assume 18070-54 for 54-56? ill be useing stock 1k2k3k4k cam set.
the exhaust valves i have say hd made in usa and a 33 on bottem the intake say hd made in usa and are about 5.558 long...exhaust look a bit longer.5.570
the valves came out of a part motor i picked up that had one of the three sets of heads i have on it so i assume it was run that way before.


other question is 2 sets of the heads have part numbers raised and cast onto the surface of the heads with a E under them...the other set has the same numbers but is stamped into the head and has a 1 under it ...is that set a early set or?
any input will be great.
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Re: k heads

Postby EKHKHK56 » Sun Nov 30, 2014 11:10 pm

Hi. The Stamped #s are early, the Raised Cast #s are later. Early heads for K fit early small intake valves. KK had WR size intakes requiring relieving the bench to clear and for flow. Early heads stock are all rough cast externally. Early heads have a different Fin pattern. -54 Heads are rough cast exterior and relieved for the larger intake valve and cam, and flow. For KHK they are relieved more for the higher lift cams, and flow, same as KK. KHK heads have the Outside Fins polished only. Clearance above the open valves and combustion chamber must be checked and corrected during mock up if needed. Hope this helps, Erik
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Re: k heads

Postby sean » Mon Dec 01, 2014 12:02 am

that helps ty.,..so the -52 with cast numbers i have are relieved only on one head and not the other,all three sets have the same relief on the rear for some reason and not the front?was that for any reason or did they run different valves in the rear on early -52 motors?
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Re: k heads

Postby sean » Mon Dec 01, 2014 12:05 am

i posted one spare set on ebay today which shows the relief and the part numbers ...http://www.ebay.ca/itm/161503470138?ssP ... 1555.l2649
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Re: k heads

Postby EKHKHK56 » Mon Dec 01, 2014 12:42 am

The first head has had Filling and Shaping done to the combustion chamber in an attempt to copy the "Ice Cream Cône" shape as I call it above the intake valve that is the last and best KR design for Flow and Horsepower. The KR heads like that are Very Cool so Ice Cream Cone style works double. See KR service bulletins for Blueprints. The second one is also non factory relieving, it may be out of spec for clearance above open valves or if OK need to be blended. H-D would have used valves, cyls, and heads in pairs so front & rear should have same specs.
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Re: k heads

Postby sean » Mon Dec 01, 2014 7:05 am

all 3 sets i have are the same ,the other two are in much better shape and dont apeer to have any work done ,one side has relief and one wont,the plug hole is square with the relief and other one is more a radius leaving the plug hole but no relief...nothing has been welded or filled on the other sets.looks stock.the set i posted had a bunch of dings and i think the valves were floating on someone and it was repaired....someone else has a set of heads online with the same numbers and the same mismatch relief...maybe thats why my numbers dont match the book numbers for -52 heads even though they all have -52 numbers?
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Re: k heads

Postby Mayday53 » Mon Feb 02, 2015 6:00 pm

Sorry if I jump in wrongly. I am also restoring a 53 K model with a 55 KHK motor installed - original owner said he swapped it out in 1955. Well, my heads do not match the books either. Specifically, my heads have the PN's of 16684-52 and 16682-52. both look good and the ports are mirror images of each other. The owner said he never changed them out...does that sound legit based on the part numbers?
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Re: k heads

Postby Mayday53 » Mon Feb 02, 2015 6:36 pm

Here are the heads I discussed:
Attachments
55 KHK HEADS.jpg
Current heads
55 KHK HEADS.jpg (177.04 KiB) Viewed 20811 times
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Re: k heads

Postby levelhead » Thu Feb 05, 2015 10:34 am

I believe Harley part numbers are different then the casting numbers ...they are very close sometimes(one digit off)...but they are different.
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Re: k heads

Postby wz507 » Mon Feb 06, 2017 6:00 pm

Hello, it’s the ole ’56 KHK basket case neophyte again, trying to learn something about K model heads. I’ve known since the acquisition 5 years ago that I had multiple sets of heads in the basket, and that one set was good and one set was cracked so figured I was good to go. Well…….. knowledge is a dangerous thing and I now realize after cleaning them up and inspecting that the good set is for an early engine and the cracked set is for my engine (never knew prior to this that 2 different heads existed). So I ended up with nice set of heads I don’t need and a set of cracked heads I do need. Curious to know if people have been repairing such items. I know that almost anything can be repaired if the desire is there, but one of these heads looks like a real bear to take on as it is cracked all the way through in multiple places.

In reading this thread from the beginning I note it is full of useful information, but does not contain side by side comparison pictures of the early and late heads, so it is my intent to provide such content, since I’ve got the cleaned up heads right in front of me now. Also, some of the previous images in this thread were ebay related, thus no longer visible, so a more permanent image record is desirable.

Although I have a very limited knowledge of this subject, hopefully others with superior knowledge will jump in and help and in the end we’ll all end up being better informed. I think a good place to start the conversation is with the part #’s from the February 1956 K Model Spare Parts Manual that should contain the entirety of head information relevant to 1952-56 consumer K models (not the racing parts).

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 17707 times

The Spares Manual content and the earlier dialogue in this thread suggest that 2 basic head sets exist, the early heads for smaller valves and lower lift cams, and the later heads for larger valves and higher lift cams. The only thing I have to go by in this matter are the casting numbers on the heads in my possession, which are described below and are consistent with other’s earlier comments in this thread.

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

Below are pictures showing the 4 castings described above from various angles.

Combustion chambers of early K model heads
low res early K model combustion chamber.jpg
low res early K model combustion chamber.jpg (106.2 KiB) Viewed 17707 times

Combustion chambers of late K model heads
low res late K model combustion chamber.jpg
low res late K model combustion chamber.jpg (101.64 KiB) Viewed 17707 times
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