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Valve springs


Mick O'Connor
 

I got new ‘double’ valve springs from Jab with my head overhaul kits.
I’ve been advised not to use them on a solid lifter as they may accelerate can love wear. Manual says ‘you must’ renew valve springs at top end o/h. Out of curiosity I made up a jig to measure the spring strength.
Double springs measured 6kg, old single spring same at 6kg, big spring from double set on its own 5kg and the small inner spring 1kg.

Consider that !

Mick


Laurie Armstrong
 

I fitted the double valve springs about 30 hours ago to my solid lifter Jabiru and had heard the same ‘advice’ which caused some worries. It has been running beautifully though.

Thanks, Laurie

On 20 Feb 2021, at 4:50 am, Mick O'Connor via groups.io <mickoconnor909=btinternet.com@groups.io> wrote:

I got new ‘double’ valve springs from Jab with my head overhaul kits.
I’ve been advised not to use them on a solid lifter as they may accelerate can love wear. Manual says ‘you must’ renew valve springs at top end o/h. Out of curiosity I made up a jig to measure the spring strength.
Double springs measured 6kg, old single spring same at 6kg, big spring from double set on its own 5kg and the small inner spring 1kg.

Consider that !

Mick





Mick O'Connor
 

Laurie,
I guess it will take a longer than 30 hrs to have detrimental effect ?
Got to assume that lots of solid lifter Jabs have had double springs installed.
Still strange that my tests showed strengths to be same

Mick

On 19 Feb 2021, at 18:47, Laurie Armstrong via groups.io <laurie.armstrong88=yahoo.com.au@groups.io> wrote:

I fitted the double valve springs about 30 hours ago to my solid lifter Jabiru and had heard the same ‘advice’ which caused some worries. It has been running beautifully though.

Thanks, Laurie

On 20 Feb 2021, at 4:50 am, Mick O'Connor via groups.io <mickoconnor909=btinternet.com@groups.io> wrote:

I got new ‘double’ valve springs from Jab with my head overhaul kits.
I’ve been advised not to use them on a solid lifter as they may accelerate can love wear. Manual says ‘you must’ renew valve springs at top end o/h. Out of curiosity I made up a jig to measure the spring strength.
Double springs measured 6kg, old single spring same at 6kg, big spring from double set on its own 5kg and the small inner spring 1kg.

Consider that !

Mick









Ron Milan
 

Mick:  If you search the archives, you will discover that I mentioned sometime ago that the double spring is/was not necessarily equated to more spring pressure.  I feel that double springs have several potential advantages, if one brakes there is still some spring pressure to hold up the valve and double springs should have a greater dampening effect.  

What height did you measure this 6kg pressure, installed height, full lift height or other dimension?

I certainly would use the double springs as long as there is no coil bind during the compression of full valve open height.

Again my two cents worth your mileage and results may vary!

Ron M


-----Original Message-----
From: Mick O'Connor via groups.io <mickoconnor909@...>
To: JabCamit <main@jabcamit.groups.io>
Sent: Fri, Feb 19, 2021 12:50 pm
Subject: [JabCamit] Valve springs

I got new ‘double’ valve springs from Jab with my head overhaul kits.
I’ve been advised not to use them on a solid lifter as they may accelerate can love wear. Manual says ‘you must’ renew valve springs at top end o/h. Out of curiosity I made up a jig to measure the spring strength.
Double springs measured 6kg, old single spring same at 6kg, big spring from double set on its own 5kg and the small inner spring 1kg.

Consider that !

Mick






Mick O'Connor
 

Disadvantage of looking at old items is that that they can be out of date and you lose the advantage of new comments/information.
I made a lever mechanism that compressed each spring from free length to coil bound. I used a spring balance to apply the compression.
Tried different methods but all showed double spring same as my old single spring. My old spring was well within length spec in manual 

Mick

On 20 Feb 2021, at 02:33, Ron Milan via groups.io <ronmilan@...> wrote:

Mick:  If you search the archives, you will discover that I mentioned sometime ago that the double spring is/was not necessarily equated to more spring pressure.  I feel that double springs have several potential advantages, if one brakes there is still some spring pressure to hold up the valve and double springs should have a greater dampening effect.  

What height did you measure this 6kg pressure, installed height, full lift height or other dimension?

I certainly would use the double springs as long as there is no coil bind during the compression of full valve open height.

Again my two cents worth your mileage and results may vary!

Ron M


-----Original Message-----
From: Mick O'Connor via groups.io <mickoconnor909@...>
To: JabCamit <main@jabcamit.groups.io>
Sent: Fri, Feb 19, 2021 12:50 pm
Subject: [JabCamit] Valve springs

I got new ‘double’ valve springs from Jab with my head overhaul kits.
I’ve been advised not to use them on a solid lifter as they may accelerate can love wear. Manual says ‘you must’ renew valve springs at top end o/h. Out of curiosity I made up a jig to measure the spring strength.
Double springs measured 6kg, old single spring same at 6kg, big spring from double set on its own 5kg and the small inner spring 1kg.

Consider that !

Mick






Laurie Armstrong
 

I doubt it will have a detrimental effect.

, Laurie

On 20 Feb 2021, at 7:00 am, Mick O'Connor via groups.io <mickoconnor909=btinternet.com@groups.io> wrote:
Laurie,
I guess it will take a longer than 30 hrs to have detrimental effect ?
Got to assume that lots of solid lifter Jabs have had double springs installed.
Still strange that my tests showed strengths to be same

Mick

On 19 Feb 2021, at 18:47, Laurie Armstrong via groups.io <laurie.armstrong88=yahoo.com.au@groups.io> wrote:

I fitted the double valve springs about 30 hours ago to my solid lifter Jabiru and had heard the same ‘advice’ which caused some worries. It has been running beautifully though.

Thanks, Laurie

On 20 Feb 2021, at 4:50 am, Mick O'Connor via groups.io <mickoconnor909=btinternet.com@groups.io> wrote:
I got new ‘double’ valve springs from Jab with my head overhaul kits.
I’ve been advised not to use them on a solid lifter as they may accelerate can love wear. Manual says ‘you must’ renew valve springs at top end o/h. Out of curiosity I made up a jig to measure the spring strength.
Double springs measured 6kg, old single spring same at 6kg, big spring from double set on its own 5kg and the small inner spring 1kg.
Consider that !
Mick