Safety valve piston type with oil bypass mod

[AndrewSlater]

I have had the oil bypass modification performed on my 1974 2.7 7R case, changed to a Carrera oil pump and have also change the oil pressure relief spring, cap and piston.

However I am unclear as to whether as part of the modification I need to change the style of piston in the safety relief valve.
Wayne Dempseys book seems to show both pistons changed to the new type but I can't understand why I need to change the safety one.

I've read the 'Ultimate Oil Pressure Relief Valve Thread ' on the Pelican website but this too is a little ambiguous.
Somebody asks the same question there but it is not answered.

Does anyone know whether it is OK to use the old style piston ( with holes ) in the safety relief valve when the oil bypass mod has been made?

As always any help would be much appreciated.
Andrew

[MT]

My understanding is:
1. You must change both pistons for the solid type (no holes in the sides)
2. You can re-use the spring and screw cap for the (horizontal) side entry valve
3. you must change the spring on the (vertical) bottom entry valve for a longer spring and fit the guide sleeve. Again you can re-use the screw cap.

Happy to be corrected!

Mick

[AndrewSlater]

Oops - not sure how I managed to post this twice.

Thanks for the response Mick I will order another new style piston.

Do you know the mechanics of why the safety valve piston needs changing - just curious and like to understand these things?
Thanks
Andrew