970 engine build

[gpmini]

Hi Everyone

Nippy's superb 970 S reminded me that soon I need to start building a 970 S motor to be used either in a 998 Cooper or a Mk1 Wolseley that is being restored. What I would like to build is a motor that really revs, not an all out race motor, but one than can be used for Sunday morning fast road use. Please could you let me in on the secrets to a high revving 970 S motor build. Cam, head, flywheel, crank mods etc. What max revs should I expect and be aiming for? Any advice welcomed.

Leon

[e-type]

To get a 970 to rev, you need a hot cam.

I would go for at least Kent 286 or a 290 SP (scatter pattern) comp ratio 10.8:1 to 11:1

A friend of mine did a 970 with a 290 SP some years ago, that went realy well. you should get 7500rpm

If money is not important, I would try the SW23T from Swiftune, just the best came out there. 8000 rpm+
comp. ratio 11.5:1 to 11.7:1

A light flywheel back plate.balanced with crank

leave crank STD

Balance rods end to end

I would go for a low diff maybe a 3.9:1

A 970 has no torque, but can cruse at 5000-6000 rpm with out feeling stressed

Regards Thomas
Denmark

[dutchacme]

I would swap the brass plugs in an orignal standard 970crank for steel ones.

WMS

[gpmini]

Thanks guys!

[gpmini]

Close to having the 970 motor assembled. Parts accumulated and work done so far:
- STR930 cam, 1.5 roller tip rockers
- Crank wedged and knife edged
- Minispares ultra-lightweight flywheel
- 1071 block bored 20 thou oversize
- ported AEG163 head or standard AEG163
- 1071 Cooper S 22G190 3 synchro box, 3.76 diff with hardy spicers

Some further advice needed please:
1. For ultimate reliability and high rev capability what pistons would you recommend? (Omegas from Swiftune I guess)
2. Should I use the standard S head or the ported (stage 3) head? (small engine capacity at altitude in Johannesburg may work better with a standard head)

Thanks!

[Vegard]

Why bother building such an engine if retaining the standard head? Get one done for your application. Smallish ports, but decently ported. I'd forget the 1,5 rockers if I were you.

[Chalkie]

Close to having the 970 motor assembled. Parts accumulated and work done so far:
- STR930 cam, 1.5 roller tip rockers
- Crank wedged and knife edged
- Minispares ultra-lightweight flywheel
- 1071 block bored 20 thou oversize
- ported AEG163 head or standard AEG163
- 1071 Cooper S 22G190 3 synchro box, 3.76 diff with hardy spicers

Some further advice needed please:
1. For ultimate reliability and high rev capability what pistons would you recommend? (Omegas from Swiftune I guess)
2. Should I use the standard S head or the ported (stage 3) head? (small engine capacity at altitude in Johannesburg may work better with a standard head)

Thanks!

Swiftune do Slipper pistons for High reving motors

and best to get a 4 bolt centre main fitted if going high revs and ARP bolts also rework the Oil ways, Water Ways. Just general go over it with a fine tooth comb get everything right first time, best thing to do don't wanna blow it up

[guru_1071]

and best to get a 4 bolt centre main fitted if going high revs up

why would you need to go to the considerable expense of buying and maching a block for a 4 bolt main on a 970 or a 1071?

they really dont need one as the stroke is so much smaller than a 1275 and so much sweeter running.

[Chalkie]

and best to get a 4 bolt centre main fitted if going high revs up

why would you need to go to the considerable expense of buying and maching a block for a 4 bolt main on a 970 or a 1071?

they really dont need one as the stroke is so much smaller than a 1275 and so much sweeter running.

Thought it would still put an effect on the centre main hmm guess you learn something new every day

[gpmini]

Finally the 998 motor has been pulled, about to make way for the 970. Looking forward to the first drive

[dutchacme]

looking good.

could you perhaps post a photo of the fitted watepump, curious how you modified it.

wim (former kaasie)

[Cables]

Right, me and a friend are about to build up a 970 S engine for another friend, so far we have a complete engine, and he's planning to use a 7 port aswell.

Were thinking to get the bottom end balanced, with ultralight flywheel, but we're at a blank when were thinking about cam's, and diff's etc.

Were thinking if he does use the 7 port it does add a little torque and should tame a wilder cam, so 286ish we're thinking? And maybe 3.4 diff?

He wants it as a fun car but that can use to go shows

[gpmini]

A pinhole leak in the water jacket of the refurbed and lightly ported AEG163 head I bought at the British Mini Day at Himley Hall in May caused a slight setback. Last week we finally set up the fueling on a dyno and I took it for its first real drive this weekend. Above 3000 rpm it is the sweetest little motor I've ever had. It simply races through the gears and is beautifully smooth cruising at 5000 - 7000 rpm.

The STR930 cam doesn't like dipping below 3000 rpm though, where it will spit and sputter and treat you like someone learning to drive for the first time. Slightly richer needles, oversize water pulley, more fueling and ignition tweaks, and with a few more miles covered I'm scheduled for another dyno run where we will see where she peaks. I plan to run it alongside my son's 1071 and my 1275 'hotrod', and will share the plots here.

I have a 3.67 diff, although with this cam it would probably be even better with a 3.9. I'd love to hear how the 7 port works on your 970. That's on my (very long) wish list.

[leonrjohnson]

I have just finished a 970 rebuild, and have it fitted to my Clubman: what a sweet little engine
You may want to look at some of my rebuild photos:
https://picasaweb.google.com/1174328332 ... redirect=1

[Pete]

I remember driving a very unimpressive , barely drivable 970 rally car years ago and thought to myself the only way anyone would build an engine like this would be to fulfil a class limit in off road competition , which many obviously did, unless you're a masochist of course.

Contraversial maybe, but a good point ?

[Cables]

its mainly cause he's got it, it doesn't owe him a penny, and its his tribute to his dad, who built him his other car, and passed away a few years ago.

We're gonna say, lightened and balanced bottom end, not sure is its had a rebore, but maybe slipper pistons, minisport race 7 port, 286 cam, lightened flywheel, 3.4 or 3.6 diff

[KA2S4]

I wouldn't recommend a 3.4 diff for a 970.

3.76 at the highest, 3.9 good all round road car, and 4.1 to get the most out of the motor.

It depends on the roads you intend to drive it on, but my 970 on a 4.1 will pull 100mph at about 7200rpm, and cruises very quietly (for a mini) at our open road limit of 62mph.

J

[Vegard]

From what I've learnt, a 7 port on a 970 with a "wildish" cam would be quite userunfriendly. The ports on the 7-port head are quite big, and a 970 does NOT need that to produce mid range torque. This is the theory.
I've never tried so will happily stand corrected.

[gpmini]

Pics of the 998 (now 970) Cooper. Hilo's and adjustable suspension next, as she rides on stilts. 6J Minilites too wide and swopped for angry looking charcoal D1's, although the offset on these not suited to an arch-less car either, so that needs changing again.

Did I mention what a fantastically smooth motor that 970 is

[4XMOKE]

Leon,
Firstly I like the short focus on the second pic, very creative, almost makes it look like a model!
Secondly, am on my way with a container to nick your car!!!!! Too nice to leave it in SA....
Roger