Hello,

I have a standard 850 and i was thinking of giving it a little more power for now, i was told by a mini mechanic to put some extractors and a bigger carb on it.

Any ideas?

I haven't completely decided to change the engine or not at this stage, i kinda like it being original at this stage.

Cheers,


Michael.

Extractors , bigger carb or twin carbs and a 12G202 (1100) head will do wonders for it . A slightly better cam would help but only if you're pulling the motor out , otherwise it'll be fine with the original .

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The way to get power out of an A-series is to help it breathe better. If you are after decent power start thinking about at least a 998 but preferably a 1100 or 1275.

As you want to keep it fairly standard, what your mech has told you is fairly right. A bigger/twin carbs are the way to go (don't go too big). The next thing to look at is the head, the 850 head in standard guise is very asthematic (a 12G202 or a 12G295 head would be better). after that start to look at the cam.

You need to weigh all the costs associated with this up. It could cost you a bit and you would probably get more power from a larger engine.

The inlet/exhaust, head and cam are a great place to start looking for more power.

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"In two years time your car will be like a lady's clothes, out of date, my car will still be in fashion when I am dead" - Sir Alec speaking to Pininfarina

the mechanic said i wouldn't worry about twin carbs from the sounds of it they are to much trouble or they were for him.

So which carby setup would be best.

Twin 1 1/4, 1/5?
Single 1 3/4?

Just some basic extractors or those LCB type extractors?

I think if the engine were coming out your right, i would just try and source a larger engine to begin with and go from there.

Thank you.

Some basic extractors, LCB's will be too big for an 850.

I prefer the look of twin's myself but a 1 3/4 would be heaps as its what alot of people put on 1275's. I think you could probably get away with a 1 1/2 but that depends on how far you are going to go with modifications in the future, it may need more than a 1 1/2.

<edit> I have seen on an old austin (of some description - was a while ago some blinged up twin 1" SU's. Looked pretty cool - dunno the availibility of them though or the bolt spacing to adapt them to a mini manifold.

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"In two years time your car will be like a lady's clothes, out of date, my car will still be in fashion when I am dead" - Sir Alec speaking to Pininfarina

I have twin 1 1/4's on the sports850 and it's good , single 1 1/2" would be similarish , single 1 3/4" would most likely be too much for it .

I'm also running a basic type 3 into 1 extractors and it's adequate (better than the standard manifold ) , you might get more out of LCB's , I'm not sure but there's not as much extra to be gained as there is in a bigger motor .

You'd be best to fit a better head (if it hasn't already been done) too , it'll also allow you to run a temp guage (850 heads don't have the sender hole in them but you can use a thermostat housing with a sender hole in it) . Any of the 998/1100 heads should fit and be an improvement , some better than others but I'm happy with the 202 .

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Search MiniSpares or Mini Sport for a Stage One - Two & Three kit and see what each offers and you will get an idea of what you can do and what the parts cost

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!

I might add that on my original Mini back in the 1960's all I added was a bigger exhaust and it made the world of difference. More by accident than intent

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!

My 850 does have a temp gauge, so its possible its already been done. Anything else i should look out for to confirm this?

Guess im going to start looking for a twin 1 1/4 setup and get the exhaust done at this stage.

Thanks for your help everyone

OK , if you take the rocker cover off you should be able to find a number cast onto the head somewhere amongst the valves and rocker posts , it'll most likely be a 12G or AEG prefix then a number though there are a few more ....

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another response saying the same thing... to do it on a budget, and to get a useful increase in performance...

a set of second hand 3 into 1 extractors - regularly on ebay for less than $50. LCB's are overkill unless you're looking for a lot of revs, short extractors are best for torque

a 1.5" SU on a standard manifold (one that has had the exhaust part cut off as they were originally cast as one piece)

According to Vizard (mini tuning guru) a blue spring and E3 needle would be the go for that setup, which can be obtained through SU Midel in Sydney, you can find them in the white pages.

put a message in the wanted forum and you'll get responses... I think I even have a cut manifold kicking around somewhere

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did I tell you that I won a trophy?

1275/Re13 cam/HIf44 carb/Headers. This will give you a fast little road car without spending too much

Pffft ..... There's something of a sort of perverse enjoyment from having a nicely tuned 850 that keeps up with things .

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we have discussed this before, but its a favourite topic of mine so
http://www.ausmini.com/forums/viewtopic ... hlight=850

like the others have said, get a 12g202 head and port polish and reshape the combustion chambers, maybe shave a bit off it to get the compression up.

Improve the exhaust/extractors, 3to1 is perfect, as is an inch and 3/4 pipe with a nice straighthrough muffler, though I've used baffle mufflers and still gotten an increase in power while keeping the noise right down.

and my preference would be for a single hs4 or inch and a half due to the fact that they're cheaper, and a little easier to tune and will be more than fine for an 850, even a worked one.

if you decide to upgrade to a 998 or 1100, you can take the modified 12g202 off the 850 and transfer it to the larger motor.

i wouldnt mess around with cams if its a road car, the last thing you want is an 850 with no power below 3000rpm

so a carby and manifold like this would suit ok? After a rebuild and a clean....

http://cgi.ebay.com.au/Mini-Rover-1988- ... dZViewItem

cheers.