Board index Flathead Power-Technical Questions, Answers, and Suggestions K-Models Coil-bind How to measure?

Coil-bind How to measure?

Moderators: Curt!, Pa

Post Wed Jul 19, 2006 4:35 pm

Posts: 54
Location: Eskilstuna, Sweden

I am fitting coils to my K cylinders.
I Know what pressure I'm looking for but i am a bit confused how to measure "coil-bind clarence".

Would .040" be a safe "coil-bind Clarence"? or .050"

If i compress the coil to coil-bind and then back .040" would that give me the maximum safe pressure of my spring.


Post Thu Jul 20, 2006 11:41 am

Posts: 919
Location: RENO,NV. U.S.A.
Hopefully you're talking about the valve springs,if so close but not quite!. The way you're doing it is putting the spring in a bind,the way I do it is to compress the spring slowly to where you can check the clearance. If you think about it this is how it works in actual operation,the way you're doing it could set the stage for spring breakage;OUCH!. BREWSKI

Post Thu Jul 20, 2006 12:09 pm

Posts: 54
Location: Eskilstuna, Sweden
Hi Brewski.

yes, its the valve springs that I'm testing. Its very close to start up and I'm in a delirious state of assembling :shock: so i forgot to say it was regarding the valve springs

I'm doing it backwards because i'm trying different springs from car engines that could provide the fully open pressure i'm looking for (200psi).
I found the right springs today.

(Coil bind - .040) is where it will be At full lift (maximum compressed). then i add the length of the lift to get the seated pressure. I just wasn't sure of how much Clarence i would need in the springs at full lift.


Post Thu Jul 20, 2006 12:28 pm

Posts: 323
Location: north central Ma.
Never take a valve spring to bind! It will weaken them and set up stress rissers. Messure installed height (from spring seat to retainer) with dial caliper then subtract lift = compressed height. Now measure the coils and x by number of coils = bind height.

Now you need to check after assebly as well most guys set for zero lifter clearance and roll the crank so cam goes to full lift you sould have the clearance spec for that spring or a little more.
Check with feeler gauges.

Don't for get installede hieght varies betwwen springs for open and closed presures so the first measurement needs to be done at installed height at the rate you need.

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Post Thu Jul 20, 2006 1:52 pm

Posts: 587
Location: Crewe, Great Britain

Hi All,

The kh shop dope sheets say shim valves 30 to 90 thou before coil bound

KH spring rates: under 135 lbs they should compress from 2"15/64 (K/W free lenght) to 1"39/64


Post Thu Jul 20, 2006 2:12 pm

Posts: 919
Location: RENO,NV. U.S.A.
Actually,if you're using car valves springs it would be better to use a valve spring tester(GOODSON's) has a relatively inexpensive one) this would tell you the pressure @ a certain height and possibly eliminate the need to check for coil bind at all.,depending on the # of coils @ the installed height. BREWSKI

Post Sat Jul 22, 2006 7:08 am

The usual safety is .020" between each of 3 pairs of coils.
I'd be surprised of you can find a spring with 200 open that fits into your covers - what's it from?

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