67-1496 Oil pressure relief valve spring

[KeithJ]

The one on the right should not be used as the ends are not closed (round) as the others, a ball would not sit square.
Cheers

Ah, but what about the PRV's with a bucket type plunger?

What's a bucket type plunger?  Is that what is used in the SRM unit?  Surely a ball resting on a narrow seat will seal better most times as a plunger on a face could be kept from seating due to debris?

[KeithJ]

G'day Keith.
The one on the left is the non return valve spring from inside the motor. The center one is the PRV spring. The one on the right should not be used as the ends are not closed (round) as the others, a ball would not sit square.
Cheers

Looks like SRM spring has open ends:
https://www.shop.srmclassicbikes.com/product/oil-pump-spring-a50-a65-a10-anti-drain-valve
Could not attach a photo but will try.

[Greybeard]

What's a bucket type plunger?

Sorry if I've caused confusion. The SRM pressure relief valve has a bucket shaped piston, something like this:

[KeithJ]

What's a bucket type plunger?

Sorry if I've caused confusion. The SRM pressure relief valve has a bucket shaped piston, something like this:

Thank you. I thought it somethink like the photo.  Just not seen inside one before.  Still don't understand why a plunger set up is better?  As long as a ball has a good seat to seal on, all should be well?  Whereas, a flat face is likely to get debis under it and perhaps not seal as well?
Having the correct spring will apply to both set ups.
Living and learning.

[Rocket Racer]

Keith, the plunger ones are more progressive, as they lift they open the side holes, whereas the ball type blow through more directly once the ball lifts. IMHO its worth checking the blow off pressure and also being sure the PRV thread is a good fit and not loose in the cases as that can result in zero pressure to the crank. The ball type are more prone to leakage as very limited seating area if not properly seated

Several A10's here had pressure issues and I fitted a oil pressure gauge to see what was happening after a rebuild on two of mine. I run a Les Williams Triumph type and is was exceeding 80psi on start up and at idle hot. With washers added we have it operating between 60-70 PSI hot. The engine does run a timing conversion so doesn't have the pressure loss of a timing bush. I'm not far from having my stock motor running and expect the pressures to be far lower, but we've still set the blow off lower than it was as supplied.

[bikerboy]

To be honest I would just buy new springs and be done with it they are only pennies

[KeithJ]

I did that’s why I ended up with three springs.  Now much wiser!