K & KH Valve Springs

Production K Models

K & KH Valve Springs

Postby starcain » Fri Jan 25, 2019 2:04 pm

I'm trying to do some research on identifying what valve springs were used in the KK. The parts books say they used the same 18201-52 spring that the K uses. The factory document that shows the instructions for installing the "Special Roller tappet Kit 18489-53R" also known as the "Competition Cam Kit" seems to indicate a different spring was used P/N RO 168-32. More on that later. I may start a KK specific thread to address some of the KK issues.


I have a couple sets of both K and KH valve springs. All are used springs. I know these all came out of K or KH cylinders as I have never had anything other then K or KH cylinders around. I decided to check these springs out for free length and compare them to the specs in the Shop Dope Service Bulletin "Valve Spring Testing Information". All the springs vary slightly but a median numbers are K - 2 9/16" and KH - 2 21/64".


It turns out that they all measure approximately 3/32" longer then what the specs show in the bulletin for free length. If anyone happens to have some loose original Harley valve springs around could someone measure them for length and post it. Is the document in error or are all my springs incorrect somehow? OK, I'm going to ask what may be a stupid question but one I have no answer to. When valve springs get weak do they relax and possibly get longer, or shorter, or no change in length but just simply get weaker and stay the same length?



The Special Roller Tappet Kit instruction document says that when valve is fully open spring should be within 1/32" to 1/16" from being solid. I am assuming that measurement is taken between the coils. Is that
a fairly standard spec for setting up any K valve spring?

Stan
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K & KH Valve Springs.jpg
K & KH Valve Springs.jpg (203.79 KiB) Viewed 15981 times
Valve Spring Specs.jpg
Valve Spring Specs.jpg (135.61 KiB) Viewed 15981 times
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Re: K & KH Valve Springs

Postby EKHKHK56 » Fri Jan 25, 2019 7:57 pm

The early KK used WR Valves and Springs. Yes, coil bind is disastrous to cams, followers, springs. That clearance sounds right. Later, The KK had to use the -32 Springs as the -52 ones will bind with the KK/KHK cams. Ill pull and measure some. Got scads of them.Erik
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Re: K & KH Valve Springs

Postby wz507 » Fri Jan 25, 2019 9:38 pm

Just measured 4 KH springs and they were just slightly over 2-21/64" so in perfect agreement with your measurements.

Generally when a spring fatigues it gets shorter. If it is shorter, the helix angle becomes lower and likewise the spring force becomes lower. With use material strength likewise decreases and so too force.

As you describe, installing a spring to be just short of coil bind at full lift is a very typical installation for a wide range of applications, and yes the measurement is between coils. Depending on the application springs are often set up even tighter for demanding applications. Setting the spring up tight helps to reduce damaging harmonics that occur in valve trains at high speeds. Less than optimally set-up valve trains at high speed can tend to make the spring look like a Jello jiggler. After watching the video it may be more obvious how a tightly shimmed spring can assist in reducing harmonics.

https://www.youtube.com/watch?v=WtqDHJDN79w
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Re: K & KH Valve Springs

Postby thefrenchowl » Sat Jan 26, 2019 7:41 am

KH spring free length:

Image

KH spring coil bind:

Image

KH spring coil bind plus 2mm (I personally would not go for a lower figure...) Whatever you choose, insert shims between collar next to cylinder and spring until you reach you chosen figure at full valve lift:

Image

Word of warning: You can buy the right hand side aftermarket valve spring as a stronger KH replacement spring, shown next to OEM KH one on left:

Image

It has one more spire than the OEM KH spring.

Might work on a KH, but will go coil bind before KK/KHK cam fully opens the valve...

Do not use...

Patrick
Last edited by thefrenchowl on Sun Jan 27, 2019 5:38 am, edited 3 times in total.
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Re: K & KH Valve Springs

Postby starcain » Sat Jan 26, 2019 8:11 am

Thanks guys for your input. Kurt, the Jello Jiggler was an eye opener. I had no idea. Thanks for the descriptive explanation. The question for me then becomes what is too tight. What actually is coil bind? Is it when the spring becomes completely solid or close to solid? What I am trying to establish is whether using a K valve spring with a KK cam is a viable set up as the parts books says? My feeling is it isn't. The installation instructions for the KK tappet kit shows it using a RO 168-32 valve spring. I have found a couple of sources that indicate that valve spring is a 18201-32. KH valve springs are 18200-32 so not the same spring.

Erik, yes the early KK did use WR valves but I don't believe they used WR valve springs. The WR didn't come out until 1941 and the spring in the tappet kit is a 32 part number. The 45" models for 1932 were the R,RS,RL and RLD. The Rl was a high compression motor and the RLD was the Special Sport Model. I am thinking that the RO 168-32 valve spring is from one of them?

I mocked up a motor, through a set of KK cams in it and tried a couple of different valve spring set ups. The picture shows a front intake with a K valve spring with a KK cam. The cylinders didn't have the valve covers on it or a gasket behind the valve guide. I added shims to make up for the valve cover and gasket and made a .111" valve spring spacer because I didn't have any of them. I would like to know what one looks like. According to the parts book 52's and 53's didn't use a upper valve spring collar like the KH's did so I am assuming that the .111" valve spring spacer was used in the same manner as the upper valve spring collars on the KH's. When I roll the motor over and get the valve fulling open I only get a .020" gap between the coils. That is only .005" bigger then 1/64". That's not much. The Tappet kit calls for a coil gap of between 1/32" and 1/16" Does .20" gap seem practical? That's why I ask again what is too tight?

I'm going to get into more specifics on the KK in a separate thread but for now I just want to establish whether using the K valve spring with KK cams is a viable set up. I'm thinking not???? Opinions please.

Stan
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Re: K & KH Valve Springs

Postby starcain » Sat Jan 26, 2019 8:26 am

Thanks Patrick for the pictures. In your coil bind picture it looks like there is still a little gap between the coils? If that is so then would you confirm that the picture I posted of the K valve with only a .20" gap between coils to be in coil bind mode?
Thanks,
Stan
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Re: K & KH Valve Springs

Postby Mutt » Sat Jan 26, 2019 8:45 am

coil bind is where the spring is completely closed. If you can stick a .020" feeler gauge between each pair of windings on your spring with the valve all the way open, that would give ya .020" x 9 =.180" clearance which is plenty
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Re: K & KH Valve Springs

Postby thefrenchowl » Sat Jan 26, 2019 8:54 am

Coil bind is coil bind, ie all the spires touching each others. But not more compression, otherwise the spires start to move sideways.

I would not measure the play between each spire.

Do as I show, measure spring length when coil bind, add about 1,5 to 2mm/60 to 80 thou and that's the max length your spring should be once compressed at full lift by your KK/KHK cam.

If you do a full lift without any shims, that measurement minus (coil bind + 60/80 thou) is the amount of shim thickness you'll need.

BUT: usually, on a street bike, even a KK or KHK, you don't need to shim outrageously: the KK/KHK cams are grinds done before the Sifton experiments with the Joe Leonard KR cams in 1954 that resulted in better ramps, double springs and the KR becoming next to unbeatable.

Hence your KK/KHK cam is probably more prone to bouncing a touch EVEN if it's shimmed out since the ramps are not optimized. Better safe than sorry, leave a bit more clearance for bouncing factor!!!

Any valve spring getting coil bind in an operating motor is a disaster waiting to happen...

I have revved my KHK around 7500rpm in the gear changes and never shimmed my OEM KH springs and never experienced serious valve bounce. My supercharged KHK is not shimmed either... and in 2013, it did 8 passes + of 2 miles flat out at circa 5500rpm at Bonneville between 115 and 122 mph...(and these are the springs that were in the motor when I bought it in 1986...)

Patrick
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Re: K & KH Valve Springs

Postby starcain » Sat Jan 26, 2019 10:48 am

Thanks Guys, this is great information. I consider myself a hobbyist and lack specific knowledge in some areas of the big picture. The valve springs is something I have been wondering about for awhile. Am I to believe then that the specs given in the "KK tappet kit installation instruction document" that says to set up spring to within 1/32" to 1/16" from being solid that means collectively over all coils rather then in between two coils? So if the spring has 11 coils like the K spring has and your going for the 1/16" ( .062") mark you would have roughly .006" between coils since there are 10 gaps in a 11 coil spring? I think that falls in line with what you are saying Patrick when you refer to .60" to .080"? When I think about it now 1/32" to 1/16 inch would be .031" to .062" between each coil and collectively would be .310" to .620". So obviously that can't be right. I'm starting to get a much better understanding.

I'm still trying to figure out what the .111" (18223-53) valve spring spacer looks like. A picture would be great if anyone happens to have some of these laying around.
Thanks
Stan
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Re: K & KH Valve Springs

Postby thefrenchowl » Sat Jan 26, 2019 12:37 pm

31 thou on a brand new 1953 engine in 1953 might work, but not on a 60 years old engine unless it is all new re-made today...
62 thou seems more like a value to follow to me...

But as I said, if you have 120 thou on your street engine, you won't notice a difference, neither will the engine... These K and KH springs are tough, the poundage they give fitted and at rest won't depend that much on the shims added.

Whatever spacers you're making, make sure they have a shoulder and that it's tight to the spring ID so the spring won't move left or right...

Patrick
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