Valve Springs Upside Down

[NevenM]

Hi

I've just finished the long block and have now learnt that I should have oriented the Outer Valve Springs, I don't think this is a major though I could change them.

Any comments

TIA

Neven
73 911E 'Eva'
70 914/6 'Eric'

[126coupe]

the bottom of the spring has slightly tighter coil

[NevenM]

Yes, but is it critical? The only reason I can think for orientating them is that this lessens the moving mass

Neven

[126coupe]

Yes its critical, an upside down spring would put more strain on the rocker arm ......... check all 12 of them

[911pcars]

The spring should have the same tension characteristics regardless of which end gets pushed. If the spring is progressively wound, the lower tensioned portion will compress first.

However, the tighter wound end would be slightly heavier, thus you don't want this end moving as much (with the rocker arm). How does that sound?

Sherwood

[geof33]

Originally posted by 911pcars
The spring should have the same tension characteristics regardless of which end gets pushed. If the spring is progressively wound, the lower tensioned portion will compress first.

However, the tighter wound end would be slightly heavier, thus you don't want this end moving as much (with the rocker arm). How does that sound?

Sherwood

Sherwood,

No to be arguementative, but the moving mass is at issue when it comes to compression. That's why progressive springs always have an orientation depending on application. If what you said were correct you could spring a sus system any old way. That's not the case though. Progressive springs always mount in one direction only, depending on where you want the load given the mass.

I agree it is critical to mount the springs correctly as the initial movement of the valve needs a lessor spring rate for control in the start of it's stroke.

[Wayne 962]

I tend to agree with Sherwood's statement. As a mechanical system, the spring should respond to compression (not tension) in similar manners, regardless of whether it's placed in one orientation or the other. The force on one end is countered by an equal and opposite force on the other. Reducing the moving mass would mean putting the heavier part closer to the chassis.

I'm just speculating here - I don't know for sure.

-Wayne

[racing97]

In regards to the Springs they are basically Non-linear in design.
This manufacturing process effectively decreases the number of active coils as the spring is compressed and the rate increases.
It does not have a single natural frequency but passes through a range of natural frequencies instead. It does not effect the rate but the harmonics. It is a little more complex to manufacture and is not the cure for a materials issue.

Best regards