Hi all,

I have just done a warm engine compression test on my 1275. This engine (mini) was taken off the road back in 1996 and the last time it was turned over was back in 2000. I turned (ie idling) her over about 2 weeks ago and this time today I had the equipment to test the engine.

I did not squirt any oil down the spark plug holes beforehand.

From right to left (facing the car) - sorry don't cyclinder number specifics:

1: 150
2: 140
3: 150
4: 125

How is this for an engine. I think it is ok but the 125 was a bit lower than the others though.

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Cheers,
Rob.

10psi variation is considered normal, but 25 is a slight worry.
If it's been parked years it could just be a bit of corrosion on a valve seat.
I'd run it a bit, adjust the valves, then redo the test.

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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.

Thankd Drmini,

What would be a good result for a compression test. Is 150 ok or should it be higher?

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Cheers,
Rob.

The compression pressure you get depends on lots of things, chiefly the C/R, and the camshaft specs.
So hard to say without knowing this.
More important is lack of variation between cylinders, if you are checking engine condition.

BTW I hope you are holding the throttle pedal down, and spinning it with all plugs out.

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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.

Well, good news.

I let the engine idle for 2x20 minute sessions and did another compression test today.

The cylinder that was only getting 125 was now hitting 145. As DrMini stipulated - must have been a bit of corrosion on the valve.

At least this is one positive for this engine but then again I never pushed Frodo hard for the 5 years I was running him back in the 1990s and I was always diligent with general maintenance.

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Cheers,
Rob.

Sounds a little better than my 998 at the moment. When I tested it the other day I ended up with the following:

1 = 55
2 = 125
3 = 125
4 = 125

I'm also getting pressure forcing oil out around the dip stick. Oh well, might have to tend to that soon

Ziff

that 55 is a worry....

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1964 Morris 850, 1330 Supercharged - 81.8hp atws.
1975 Leyland Mini S 1100S powered - Nice and reliable.
1977 Leyland Mini LS - Project LS-T