I have had two Minis in the past with the pump connected. In both cases the increase in power was noticeable but not really significant.

I have been told that the pump costs about 3bhp to the engine, which on a standard 998cc which has a factory listed output of 38bhp is about 8%.

Most people including myself, have removed this pump, which has provided a little more power and considerably greater access to the alternator.

However, as a result, there are very few original Minis getting around that still have this pump fitted. If your car is otherwise in very standard spec, it might be worth considering leaving it is is.

It may not be "working" because of the modern fuels being used, but if it "functioning" in the way it is intended it may make the car historically more significant.

It is of course entirely your decision, so the choice really comes down to if you prefer a little extra power and easier maintenance on the alternator etc, or if you want the car to be historically accurate, or if you want a compromise, as suggested, where you prevent it from operating but keep it in place so it "looks" right.

Cheers,
Watto.

Thanks for that watto.

If I decide to remove the unit, what is the best way to plug up the holes in the head?

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1977 LEYLAND MINI SUNSHINE 'S'

A nice touch is to use cap head style (allen key) grub screws.

You could use hex head bolts or often I've seen the original tube nuts brazed over and screwed back in.

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The 4 threads in the head are 7/16 UNF. Grubscrews are expensive as this size ain't popular.
A fairly neat way to plug the holes is screw 4 old seatbelt bolts in there, then cut them off and dress flush with an angle grinder.

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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.

if you take it all off, keep everything intact and put it up for sale, someone restoring a car will want it

yeah, especially the gulp valve. How many of us can boast having a gulp valve

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1967 Cooper S - new front bearings to do.
1965 Cooper S shell - Slow progress. No time or money!
1966 Deluxe- next rustoration!
Mk 2 & XJ6 Jags. Less said the better.

A gulp valve is a good thing isnt it?

What about the charcoal canister?

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1977 LEYLAND MINI SUNSHINE 'S'

Years ago I dismanted the pump on my Gemini and removed the vanes, as well as blocked all the hoses. That way it looked like it was working to the average cop at the roadside. I also had a Weber hidden under the stock airfilter.

If you drove a Gemini in Sydney in the early 90's, underbonnet inspections were a regular occurence!

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Brett Nicholson
Greendale (near Ballan) VIC.
1971 Morris Mini Moke
1966 Austin Mini
1965 Morris Mini Traveller
1973 LR Series 3 88
2007 LR Freelander 2

My sister-in law has a late 77 clubman 998 with the air pump fitted. As everything else on the car is original, we kept it on. It doesn't make the car any slower in comparison to our standard 1100 minis. And as an original shopping cart, it does the job

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88 Rover 1.3i "Reggie"
99 Rover 1.3i “Grover”
12 Mini Cooper S "The shitter"
17 Mini Clubman JCW “Noddy”

Yeh. I will leave it on simply because everything is original and not modified. I was just interested in what to do if I were to take it off. You never know what might happen down the track if I ever choose rebuild the engine. But for now its fine.

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1977 LEYLAND MINI SUNSHINE 'S'

I think in time when everyone starts restoring the late mini's and mokes to standard, the original air pumps will be in demand. As will the pollution heads!

Yeah. I'm going to hang on to mine.

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1977 LEYLAND MINI SUNSHINE 'S'

That is so correct ...

I'd say he should take it all off and give/sell it to me ...

But id be very biased .. since my car is missing it and it WANTS it back

Im afraid you will have to keep looking mate.

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1977 LEYLAND MINI SUNSHINE 'S'