18 replies to this topic

[tmsmini]

Looking for specifications on the springs. This is what I found on the springs.

Somerford
6K853        SPRING, oil pressure relief valve      Standard fitment.
AEA536     SPRING, oil pressure relief valve   Uprated fitment, plus 1961-71 Cooper models.

Mini Spares
6K853 - OIL PRESSURE RELIEF VALVE STANDARD SPRING
AEA536 - OIL PRESSURE SPRING ORIGINAL COOPER "S"

 

Mini Spares says the "Cooper S" spring can be used with the ball. I know many people says they are still too long.

I found a reference to spring length in an old book by Marshall and Fraser, originally written in the 60s. It just says the spring should be 2 7/8 inches long, no info on spring pressure.

 

I thought I had a reference in an old manual that specified relief pressure, but I cannot find it.

More out of curiosity than anything else. The longer spring is the lower pressure version

 

Attached Files

•  OPRV spring.jpg   93.15K   1 downloads

[nicklouse]

Some reading for you.

https://www.theminif...huttle-vs-ball/

but no idea what you are asking.

[Spider]

It does look like the longer spring has a lighter gauge wire to it, though, that maybe an illusion.

With the Oil available these days, 60 PSI is well more than enough.

[timmy850]

There was a similar discussion on the ausmini forum a few months ago. The different length two springs had the same weight at the same fitted length due to the different gauge of wire.

https://www.ausmini....hp?f=2&t=101895

[tmsmini]

No real question just curious what the specs were/are and the possible reason for the difference. Maybe it was a Browning book that had the specs.

The ausmini discussion looks like the same sort of question. I have not logged in there in quite awhile. My login does seem to be working, but thank you for that link.

And as always Spiders explanation is great!

[Spider]

No real question just curious what the specs were/are and the possible reason for the difference. Maybe it was a Browning book that had the specs.

The ausmini discussion looks like the same sort of question. I have not logged in there in quite awhile. My login does seem to be working, but thank you for that link.

And as always Spiders explanation is great!

 

It's a little 'interesting' too that one is wound left hand and the right.

 

I'll add here to that the MPI ran 30 PSI Oil Pressure. I'm not sure if that was done with yet again a different spring, or a different seat in the block.

[Spider]

I just looked up what factory info I have on the springs, which isn't a lot sorry, but the 6K853 should have a free length of 2.86".

[tmsmini]

I tried finding some of my old books, but they are stored away. The first edition of the Marshall and Fraser book states 2 7/8 which is the same as 2.86. A later version of he book states 2 55/64, not sure what difference a 64th of an inch makes.

 

I do remember an old wives(racers) tale of needing 10 psi for each 1000 rpm.

I would be curious at what RPM and temp this is for, "MPI ran 30 PSI Oil Pressure?"

 

The cars that I have MPi blocks in behave the same as any A series I have had, about 60 psi at 3800 RPM and 85 C.

[Steve220]

New, the mpi makes around 100 psi of oil pressure. On a new pump and bearings, the same. The return oil way from the valve is way too small and they struggle.

[tmsmini]

New, the mpi makes around 100 psi of oil pressure. On a new pump and bearings, the same. The return oil way from the valve is way too small and they struggle.

This has been my experience as well. On a new rebuild I was over 100 psi until I realized I had the shorter spring in the valve.

[Spider]

 

New, the mpi makes around 100 psi of oil pressure. On a new pump and bearings, the same. The return oil way from the valve is way too small and they struggle.

This has been my experience as well. On a new rebuild I was over 100 psi until I realized I had the shorter spring in the valve.

 

 

This is from the factory manual guys;-

 

 

I also found another reference to it elsewhere. I haven't worked on them so I've never checked for myself.

[tmsmini]

Interesting as I have that manual but never looked closely at that section of  manual RCL0193.

So I looked up that info in the manual that preceded it that cover the SPi, AKM7169

and they list the data in kg/cm² which works out to 60 psi.

 

Attached Files

•  oil pressure 2.jpg   23.19K   1 downloads

[tmsmini]

Just got back into AUSMINI and some one has posted a chart with manual numbers, user eightfifty posted it. Thank you

 

Just food for curious minds...

Attached Files

•  oilsprings.JPG   31.95K   1 downloads

Edited by tmsmini, 04 December 2023 - 05:23 PM.

[Steve220]

 

 

New, the mpi makes around 100 psi of oil pressure. On a new pump and bearings, the same. The return oil way from the valve is way too small and they struggle.

This has been my experience as well. On a new rebuild I was over 100 psi until I realized I had the shorter spring in the valve.

 

 

This is from the factory manual guys;-

 

 

I also found another reference to it elsewhere. I haven't worked on them so I've never checked for myself.

 

A few bits wrong on that i think, Chris. I've built several MPi engines, and worked with them exclusively now (only A+ i've ever owned is the 998cc in the van lol). Pressure at idle i've never seen below 1 bar - only time it's been close (20psi) is running 20w50 with the oil temp being c120C and worn bearings (race engine on a standard pump). I've logged Felix's engine on the standard pump when i first built it and it was 110psi cold at idle, dropping to around 40psi when at operating temp. Gav Wilkinson, who has a standard MPi block but turbo'd, also sees above 100psi from cold. They really are a perculiar engine!

[Spider]

A few bits wrong on that i think, Chris. I've built several MPi engines, and worked with them exclusively now (only A+ i've ever owned is the 998cc in the van lol). Pressure at idle i've never seen below 1 bar - only time it's been close (20psi) is running 20w50 with the oil temp being c120C and worn bearings (race engine on a standard pump). I've logged Felix's engine on the standard pump when i first built it and it was 110psi cold at idle, dropping to around 40psi when at operating temp. Gav Wilkinson, who has a standard MPi block but turbo'd, also sees above 100psi from cold. They really are a perculiar engine!

OK cheers for that Steve. As I did mention, I haven't worked on them, however that figure I have seen in another publication.

I gotta say though, 100 PSI ?  That's pretty high !!!