Installed height

[cgarb]

Looking at a set of Kmotion K1650 springs for a limited installed height solid roller application. If I can run +.050 locks I can get a 1.950 installed height. K motion lists this spring as a 2.00" install at 200lbs. According to K motion's website at 1.950 they should check at 233lbs. The open is 700lbs at 1.250" and and that should be at .750" lift. The cam is .692" lift. Would that be acceptable to put this springs in tighter than the recommended height? I emailed Kmotion about this but have not heard back yet.

[steve cowan]

2.00"-200lbs
2.00"-0.750"=1.250"
1.250"-700 lbs
700-200=500/0.750"=666lbs/in spring rate

1.950"-233lbs
1.950"-0.692"=1.258"
1.258"-700lbs close enough I think
700-233=467/0.692=674 lbs/in spring rate

Depending on how aggressive the lobe is and rocker ratio is being used you need to acquire recommended spring rate for your application
Hope this helps

[cgarb]

Pretty sure it is a comp catalog grind for a BBM. The catalog lists the recommended spring as a 943-16. It says it's open pressure is only 598lbs. The intake valves are a steel valve that's 5.350 long 2.200 diameter. I would be more inclined to use that spring if this was some type of small block or it had titanium valves. I was hoping the K motions would work a little bit better.

[Adger Smith]

Is that .692 Gross lift or net lift?
If it is Gross with a solid then you don't have that much valve movement = more spring clearance.

[cgarb]

The website says coil bind is at 1.150" and that is the gross lift. Lash is .028 and .030".

[Adger Smith]

I have always seen fewer problems with a little more spring quality and or pressure than too little.

[cgarb]

Kmotion emailed me back today and said I would be good to go with those springs.

[frnkeore]

I'm quite sure what the issue is here. I would be more concerned about running to far under open height than what you have for seat ht.

Most conventional springs are made to have the best harmonics, at .06 off spring bind. I try to set mine up with that in mined (and not going past .060) and not worry about what installed ht is or pressure.

In your case, with 1.9 installed, it is 1.236 open (using net lift), with 9 more lb of pressure (709). So, I can't see anything wrong with that, unless you want to run as little pressure, as you can and if that's the case, I would get lower pressure springs.

[bob460]

What about a PSI 1243 spring?

[KnightEngines]

You mean PAC 1243?
Probably the same.
They're a bit shit, loose pressure fast.

There is an isky tool room spring I use at 1.95" installed height at around 260lb on the seat, 530lb rate & will take .730" lift.
Not cheap, but they go the distance so they end up cheaper in the long run.
I'll see if I can find the part number tomorrow.

If there is 1 component in an engine to not cheap out on or under spec it's valve springs.

[SpeierRacingHeads]

I use the K1650 as my standard spring on my CNC heads. It's the best chrome silicone spring you can find.

However, the spring rates on the tester are much different than advertised.

I put them in at 1.950 a lot. But you will have more pressure than catalog and even after racing a season.

[cgarb]

I noticed that on some data tables on your website Chad. I was wondering if it was a typo or not. Thanks for the info. These heads have a lot of black carbon in the intake runners and that's why I was looking to up the spring pressure. I was thinking the 2.200 valves my not be staying under control with only 550ish open.

[SpeierRacingHeads]

I noticed that on some data tables on your website Chad. I was wondering if it was a typo or not. Thanks for the info. These heads have a lot of black carbon in the intake runners and that's why I was looking to up the spring pressure. I was thinking the 2.200 valves my not be staying under control with only 550ish open.

[PRH]

You just have to wonder how the observed specs can be so far off the advertised specs.

I’m assuming Chad is showing what the K-1650 actually tests at....... which is vastly different than what the specs are.
The rate is off by 134lbs/in.

The old Crane 96886 has similar specs to what’s advertised for the K-1650.
I had used them a few times with good results, but I’m not sure Crane sells them anymore.
(Actually, I just looked at Summit...... still seems to be a good number)

Trick Flow also has a spring that seems to fill the same requirement.
TF-16886-16 - 225@2.00/715@1.250, 1.150CB, 1.540 OD

I don’t think the “886” in the part number is a coincidence.

[cgarb]

Yes, I wonder how their site is off so far also. It says every spring in a set will check within 5lbs...so I assume someone is checking the springs somewhere in the process. Wouldn't you think they would stop and wonder...hey, this seems a little off.