The auto seats are tapped 3/8 UNC, the manual ones are not, you need to run a tap in. That's what I've found anyway.
Pull them out with a head stud, nut and a bit of tube.
Also, the autos have a cross hole drilled through them; when converting an auto block to manual, these have to be blocked by brazing up. Or fit a manual seat instead.
The holes were there to allow oil into the rear of the main gallery, because on autos the engine oil comes UP the banjo pipe from the gearbox.

[edit] You can still buy the manual relief valve seat from Minispares UK.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Thanks for the ideas - just took another look at the pressure relief valve and seat. Wasn't able to knock it in any further with gentle tapping, so other than pulling it out to put it back in again, I'll assume it's where it's supposed to be! As for the bypass valve, if my understanding is correct, it may have been stuck open and is now (correctly) closed, so no point going looking - but thinking further about it, does the engine oil hit it at pressure, or is somehow after the pressure relief valve? (Does a schematic exist for the A series oil system?)

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'68 Deluxe w/Metro engine

Matt.
My understanding of the Tasmanian fault was that the seat assembly was loose enough to be forced outwards by the oil pressure, carrying the ball/check valve with it and travelling far enough outward (ie, towards the front of the car) to block the relief hole.

I doubt this would be apparent if you tried to push the seat back in, as it would probably already be in the correct position at that stage.

Rather, I would assume that a faulty assembly would move outwards easily, whereas a proper fitting one won't be able to be pulled out easily, if at all.

That's another two bob's worth from me.

Of course, all this could be academic if the Metro engine is somehow configured differently, but it's always fun to conjecture.

Cheers, Pottsy

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Smile Up at The Trucks!

A little more on this - after today's CBR-WOLL-CBR trip (500kms?) - the car sat on 50-53psi the whole time when at highway speed. But interestingly, when accellerating off idle, past about 1500-2000 rpm, pressure would rise to about 62-65, then promptly pull back to the 50-53 range as the revs increased. Any idea what would cause this phenomenon? In my simple world, an engine should build more pressure as revs increase, limited only by the oil's temperature and viscosity, and possibly the pressure relief valve

Cheers
Matt

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'68 Deluxe w/Metro engine

That is normal. I have a ball in mine, when hot it has 75psi @ 2500rpm, as the revs get to 3000 or above it drops to 70psi and stays there. It is a feature of valves and other things called `hysteresis'.

If you want more pressure, fit a Cooper S spring (gives ~70psi).

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Thanks Doc!
Interesting.
Wikipedia says "Hysteresis is the dependence of the output of a system not only on its current input, but also on its history of past inputs. The dependence arises because the history affects the value of an internal state."

Deep thinking, right there!

Cheers
Matt

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'68 Deluxe w/Metro engine