Tuning the 998 cooper engine?

[Vegard]

comp baulk rings

I hope you didn't gpo for the bronze competition ones they wear like nothing on earth.

Always best to use the Standard Rover ones in all applications including competition.

I just pulled one out of my race engine built in 2004. I had fitted one, luckily on fourth

[Dean]

the reason for going 3.1, was for motorway speeds, the club goes down to newquay every year and its just short of 300 miles, plus on the other shows like castle combe, beauliue, which are all 100-150 miles away mainly on motorways, plus to keeping the revs down at round 70mph, on a 3.1 on 10" wheels the engine is reving around 3600-3700rpm

i have driven a standard 998 on 10" wheels and it went quite well, and also a tunes 1340 on 10" wheels which went better, but it was a bigger engine

it was something i was concerned about being a 3.1 on a 998, but for me a 3.4 will rev the engine too high at motorway speeds,so the reason for a 3.1

sorry for junking up your post on your engine build,

but if you go for what peoples have said you will get a very nice engine, get a well know engine builder to modify your head, its the place which will give you the power,

[HuwGreenMiniVan]

Dean, you might have to change down to third on every little motorway hill though? I myself would stick to 3.44:1 diff.

[Simon776]

1980's 998 Minis such as the City E had a tall final drive and with 12" wheels and I don't recall them needing 'rowing' along and if you are going for a mildly tuned 998 I'm sure it will be fine.

[robert]

yep deffo 3.1 personally .

[HuwGreenMiniVan]

The Mini's and Metro's A-plus 998 engines were desigined for low down torque to cope with those diff ratios in fourth gear, with the camshaft fitted in them. I won't change my mind, sorry, 3.44:1 is as low(or is it higher?) should go with a tuned 998 even on 10" wheels.

[JanWulf]

Hi!

I'm currently using a very cheaply to build & strong 998. It's a 9.4:1 A+ unit with a std. 12G940 (33mm valves) and a std. 1275cc camshaft and a 'Stage 1' kit. Goes well, very close to a stock 1275 - but needs more revs. And it revs happily right into valve bounce - and would probably go on to do so if I fitted different valve springs

I'm using a 3,76:1 & 10" wheels - I have no trouble there. But I rarely go faster than 65MPH on the autobahn. But the short diff realy helps it to make it an enjoyable engine on twisted country roads.

With a std. camshaft it doesn't even need valve pockets in the block. With the 'low comp' A+ pistons, CR works out to be somthing around 10.5:1.

Regards,
Jan

[Mini4Ever]

Used to have a std Inno 1001 engine with A+ gearbox and 3.1 FD. The Inno 1001 engine is basically a 998 Cooper engine with the D-tops, AEA630 cam (AEG510 Cooper S profile but narrow lobs) and 12G295 head and a single HS4 instead of twin HS2. All std except for a non-adjustable double timing chain. It went quite well: 90 kph in second at 6800 revs, top around 160kph on speedo. No idea on bhp though. Key was in this case a good distributor (123 ignitor).

PS: Have a complete Inno 1001 engine for sale as well as a good 12G295 head and a pocketed 998 Mk I block with +40 flat top pistons (circlip fit).

[alexm]

It looks like the engine i'm off to look at maybe minus the twin HS2's. Having looked at good old eBay there are some decent looking HS2's for sale but some are advertised as being for a Cooper 'S'. Now, my fairly limited knowledge leads me to believe there isn't anything different between the carbs for the 998 cooper and the 1275 s. Could someone put me right?!

Thanks.

[HuwGreenMiniVan]

PS: Have a complete Inno 1001 engine for sale as well as a good 12G295 head and a pocketed 998 Mk I block with +40 flat top pistons (circlip fit).

With the circlips holding the gudgeon pins in, I was given a tip once to make sure the gap is at the top, and loctite the circlips in, to stop any chance of them popping out at about 7000rpm, when you decide to do about 110mph/175kph down a hill, with the wind behind you!. But can't remember what loctite code it was that I used.

And another tip I had from the same person was to put a thin smear of hermatite gold non-setting gasket sealant on the block side of the gearbox and flywheel housing gaskets, because it allows movement between the iron block and alloy gearbox and flywheel housings with their different heat expansions, so prevents oil leaks from them, even though you think being bolted together won't make any difference. Never ever had oil leaks from here, but did from diff output shafts though. But changing their rubber seals fairly regularly stopped that. The problem with diff oil leaks is the brass bearings wearing out.

edit- whoops, hermatite gold, not green

[InimiaD]

It looks like the engine i'm off to look at maybe minus the twin HS2's. Having looked at good old eBay there are some decent looking HS2's for sale but some are advertised as being for a Cooper 'S'. Now, my fairly limited knowledge leads me to believe there isn't anything different between the carbs for the 998 cooper and the 1275 s. Could someone put me right?!

Thanks.

The Twin SU carbs have different markings.
The Cooper 998 carbs should have AUD 104 L/R stamped on an aluminium tag under one of the screws holding the float chamber lid on both carbs.
The 1275 S twins has the AUD 146 L/R code.
The needles, springs and possibly jets will differ from carb to carb.
Hope this helps.

[alexm]

Thanks, yes that is helpful.

In peoples opinion, will it be better to hold out and try and find the correct carbs, or if a pair of Cooper S one's come up at a fair price, should I go for those and look to change needles/springs/jets?

While this thread is open, and sort of on topic- are the starter motors for these cooper engines fairly easy to come by? I believe I need the inertia type which was fitted to all early minis? I can see Minisport have them for £65ish, but can the older ones be refurbed easily enough?

Last question for now I promise - the gearbox attached to the cooper engine is known to pop out of 2nd. Common fault and easily fixed?

Thanks in advance.

[mascher]

The Cooper and the Cooper 'S' used the same jet. AUD9141 on the left and AUD9142 on the right.

Kelley

[mk1coopers]

It looks like the engine i'm off to look at maybe minus the twin HS2's. Having looked at good old eBay there are some decent looking HS2's for sale but some are advertised as being for a Cooper 'S'. Now, my fairly limited knowledge leads me to believe there isn't anything different between the carbs for the 998 cooper and the 1275 s. Could someone put me right?!

Thanks.

Lots of the eBay carbs advertised as S are not S, the Cooper ones have a take off for the vacuum advance on the left hand carb (as you look at it from the front of the car), the S distributor doesn't have this type of advance, so the correct carb body shouldn't have the take off

[alexm]

It looks like the engine i'm off to look at maybe minus the twin HS2's. Having looked at good old eBay there are some decent looking HS2's for sale but some are advertised as being for a Cooper 'S'. Now, my fairly limited knowledge leads me to believe there isn't anything different between the carbs for the 998 cooper and the 1275 s. Could someone put me right?!

Thanks.

Lots of the eBay carbs advertised as S are not S, the Cooper ones have a take off for the vacuum advance on the left hand carb (as you look at it from the front of the car), the S distributor doesn't have this type of advance, so the correct carb body shouldn't have the take off

Is the take off the little stubby round port poking out behind the left hand dash pot on these carbs? http://www.ebay.co.uk/itm/CLASSIC-MORRI ... 3a6d55300a

[mk1coopers]

The one at the back is for a the choke cable, I suspect those carbs will have a outlet as the bracket with the round hole on the left hand side would have held part of the vacuum systems metal pipe work. The metal vacuum outlet would be on the L/H side of the carb body at the front, coming out at 90 degrees, it would look like a small arrow pointing at the inner wing (it might also be covered with a small rubber tube)

[tedmcedd]

small bore tuning is the way forward!

I had a 1098, 12G295 head and some twin carbs on ram pipes, got me 58bhp without a cam!

my dad's mk2 cooper engine has been overbored +60, ported stage 3 head (which is pretty much the 295 as the one we had with the engine was cracked) lightened and balanced crank, flywheel and rods, and he has given me the twin carbs and gone for a weber!

looking forward to getting that running!

I too like mk1, have run rampipes with no filters both on the engine above, and on my MGB, never had any problems...

If you are looking for twin carbs, and are not too bothered about them being the proper 'cooper' items, seach for midget/sprite carbs, as thing sthat say cooper and 's' in descriptions seem to go for loads! however, you will need a mini manifold, as the MG ones are too long and the floats foul the bulkhead.

Ed