Can someone please tell me what the standard running pressureis for an 1098 cc engine is, mine seems to sit on about 75 psi most of the time but sometimes will go as high as 90 psi.

What sort of relief valve do you have , is it standard or one of those adjustable types ?
50 - 70 hot on the highway is fine , idle 20 - 40 .

When you say running at 75 -90 , is this when it is hot running or cold on start up , 90 is probably getting a bit too high if hot .

these are not book settings just my thoughts .

The Cooper S and GT engines ran at 100 psi! In the context of the day with crappy oils then that was fine. Those days are gone however.

Saying that, your engine will not explode if it does run that high, but can buy a standard rated spring with valve for just a few dollars, and with a socket and extension bar takes only a few minutes to replace to baseline. While you're there you can check out the cup to see if its damaged. It may have been the cause of the problem.

http://www.minispares.com/product/Class ... |Back%20to

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Cooper S and Cooper ran @ 70psi, more when cold. Mine goes to 95 then, running Valvoline 20W/50.
I would leave the spring in that you have.

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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.

ditto - be happy with that....

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did I tell you that I won a trophy?

Mine was sitting right up the top end of the scale at 100, I dropped it a touch mainly to lengthen the life of the gauge.
I just cut a coil off the spring and linished it flat.

Much easier to just add a few sump plug washers under the relief valve cap (space the cap away from the block).. Add smaller washers inside the cap to increase pressure ...

Cheers, Ian

Have you also tried measuring the pressures with a known calibrated gauge

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"Show me the Mini!"

So its just a standard relief valve and its running at 75 when cold and goes up to 90 when hot. Havnt tried a calibrated gauge yet

One can only hope that this is a typo ...and back to front. That would be entirely normal (IMHO:)

The only time I've seen oil pressure increase as temps rise a new block was required....

Cheers, Ian

Agreed , if this is the case , i'd be more than happy with that .

I'll check the pressure again tomorrow, hopefully i just had my readings arse about........

one problem with too much oil pressure is that (if you rev it when cold) is it can act like a pressure washer, blasting away the white metal off your crank bearings

i don`t like "Too much" oil pressure,,, it`s not good for your crank bearings
& it`s also a waste of power

Twin-Cam Lotus excorts ran a MAX of 35psi

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

I'm with TheMiniMan.
Good advise Matt

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Back in the 60s, with an A series they reckoned on 10psi per 1000 rpm if you wanted the bearings to last. Can't remember who said this, maybe was Clive Trickey?
Anyhow I run 70-75 hot, and take it easy when cold. I keep it under 3500 until the temp needle moves a bit.

BTW, white metal went out with old 850s, these days the bearing shells are copper lead or aluminium tin.

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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.