Shim the Oil Pressure Relief Valve Spring

Hi All.
When you have to shim (with 067646) the oil Pressure Relief Valve spring?
I have a new spring.
I never have found before the shim into the valve.
Thanks.
Piero

pierodn said:

When you have to shim (with 067646) the oil Pressure Relief Valve spring?

Click to expand...

To check, you would have to fit either a temporary oil pressure test gauge (as sold by RGM etc.) or a permanent oil pressure gauge.

Hi Les,
i always use to replace the spring and washers with new one, but i have never used to shim the spring.
Ciao
Piero

pierodn said:

Hi Les,
i always use to replace the spring and washers with new one, but i have never used to shim the spring.
Ciao
Piero

Click to expand...

Piero,
In the Mick Hemmings engine restoration video, Mick just adds enough shims to "just rattle slightly".
Cheers,
Thomas
CNN

Piero,
In the Mick Hemmings engine restoration video, Mick just adds enough shims to "just rattle slightly".
Cheers,
Thomas
CNN

Click to expand...

??????????
This doesn't sound right to me. Am I missing something. If the relief spring rattles, it is loose, therefore it must necessarily follow that oil pressure will immediately be bleed of to the bypass circuit.

The spring is there [ under compression ] to push the relive valve closed and it should only let the relief valve off its seat if the pressure goes above [ for arguments sake, 60 psi ] the recommended max pressure.
If it is loose as the above comment suggests, it isn't putting pressure on the relief valve, so no oil pressure will result..??????????

kerinorton said:

Piero,
In the Mick Hemmings engine restoration video, Mick just adds enough shims to "just rattle slightly".
Cheers,
Thomas
CNN

Click to expand...

??????????
This doesn't sound right to me. Am I missing something. If the relief spring rattles, it is loose, therefore it must necessarily follow that oil pressure will immediately be bleed of to the bypass circuit.

The spring is there [ under compression ] to push the relive valve closed and it should only let the relief valve off its seat if the pressure goes above [ for arguments sake, 60 psi ] the recommended max pressure.
If it is loose as the above comment suggests, it isn't putting pressure on the relief valve, so no oil pressure will result..??????????

Click to expand...

kerinorton,
Well I guess you just have to watch the video. He is assembling everything with just finger pressure (no wrenches). Then he places it into the timing cover and tightens it up with a socket. He has built more engines than probably any one of us here. He must be wrong? :roll:
For those who don't have the video: If you look at the oil pressure relief valve body carefully NMT2059A
The piston must move up quite a bit before it gets to the relief holes. Mick took shims out and rattled it for the camera, which was audible. He then added one more shim, shook it again for the camera and I couldn’t hear it rattle anymore. So this is how he set it.

Cheers,
Thomas
CNN

kerinorton said:

CanukNortonNut said:

Piero,
In the Mick Hemmings engine restoration video, Mick just adds enough shims to "just rattle slightly".
Cheers,
Thomas
CNN

Click to expand...

??????????
This doesn't sound right to me. Am I missing something. If the relief spring rattles, it is loose, therefore it must necessarily follow that oil pressure will immediately be bleed off to the bypass circuit.

The spring is there [ under compression ] to push the relief valve closed and it should only let the relief valve off its seat if the pressure goes above [ for arguments sake, 60 psi ] the recommended max pressure.
If it is loose as the above comment suggests, it isn't putting pressure on the relief valve, so no oil pressure will result..??????????

Click to expand...

That isn't quite how the relief valve works. As oil pressure increases, the plunger is forced outwards against spring pressure, until at a certain point it starts to uncover the ports in the body and the valve then begins to vent oil.

SRM has a sale on bench tested, stainless commando relief valves

kerinorton write: "The spring is there [ under compression ] to push the relive valve closed and it should only let the relief valve off its seat if the pressure goes above [ for arguments sake, 60 psi ] the recommended max pressure."

Is there a published pressure at which the valve should begin to open??

Stephen Hill
Victoria, BC

Stephen Hill said:

Is there a published pressure at which the valve should begin to open??

Click to expand...

http://www.classicbike.biz/Norton/Repai ... mmando.pdf
Section C22.

Hi Piero,

the OPRV has been adjusted at the factory. If no shim is inside, it was not necessary. It is not strictly required to renew the spring because it is 40 years old. But if you renew it you have to check the valve with a gauge as Les recommended.

Ralf