34 replies to this topic

[minilee94]

No not balance the cam out that was a bad way of explaining but I'm talking about if you have mad light flywheel it will make the engine run really lumpy so if you have a lumpy cam and you run a lighter not to light flywheel it balances the engine out same as along with balancing a crank helps

[HarrysMini]

No not balance the cam out that was a bad way of explaining but I'm talking about if you have mad light flywheel it will make the engine run really lumpy so if you have a lumpy cam and you run a lighter not to light flywheel it balances the engine out same as along with balancing a crank helps

Correct. So long as you have built the engine to withstand high revs, then it's absolutely fine. As long as you don't mind having to rev it and having a quite lumpy idle.

[minilee94]

But the idle isn't that bad iv known people running scatter cams which are crap for road use and that was perfectly fine on idle just the power and was crap for road use

Balancing smoothens out the lumpiness that why it's not good to go for a mental light flywheel

Also my cam piper 285 I have a mate with a 1380 running a modified cam made by newham cams running near enough same spec as 285 on a weber carb etc standard flywheel and was okay not brilliant in traffic I'm not saying it ain't a lumpy cam as it is but you can take out the lumpiness but balancing things and lightening things which is why he has just had his flywheel lightened and balanced

[The Matt]

Having a higher compression ratio can also smooth out a lumpier cam like the 286. My 1380 ran 11.2:1 and the idle sat at around 1200rpm. Having the higher compression ratio, Megajolt ignition and fuel additives all contributed to it. But that's really not practical for a lot of applications.

[The Matt]

Also, with a 3.1 final drive you'll want grunt more than you want power at higher revs. So I'd avoid a revvier setup.

[Cooperman]

We need to be clear on what we are advising when talking engine specifications in general and cams in particular.

 

The reason for fitting a 'hotter' cam is to increase the power and/or torque. It is no use fitting a cam like a 286 which, from Kent's own data sheets, show the optimum power from around 5500 to 6800 rpm. So unless you want to be revving like that whenever you wish to use the cam to its best output, don't fit one.

I have a 286 in my rally car and, on the road, it is horrible, but get it over 5500 rpm and it is super right up to 7000 rpm. Mind you, I do have to rebuild the engine regularly.

 

It is so easy to 'overcam' an engine then find it is not nice on the road. I know that my Innocenti with a 1330 cc engine, 510 cam and 10.5:1 C.R. was much nicer to drive on the roads than my rally 'S' despite being maybe 30 bhp down. But with the Inno it gave max torque very low down, like about 3800 rpm with peak power at 5600 rpm.

 

There is a lot of 'cam hype' but often engineering sense is a bit lacking. There is no point in fitting a cam which peaks at around 6500 if your engine can only sustain revs of 5800. In fact it is a rather silly thing to do as the car will be slower, more lumpy and use a lot more fuel than if a suitable cam were fitted. A 286 is a real competition cam for high-revving engines with close ratio gears, a low final drive ratio and a low cruising speed.

[grumpy dad]

Hi

I had a swiftune SW5 in a 1275 and swap it for a AC Dodd RT1

I think the ACD RT1 is better more torque

also the service from AC Dodd is second to none

[Midas Mk1]

Phh, when someone actually drives a mini on the road, they might realise that a 286 is no where near as bad as they make out. And that after several thousand miles with a 266 / mg cam it gets boring.

[coopdog]

Phh, when someone actually drives a mini on the road, they might realise that a 286 is no where near as bad as they make out. And that after several thousand miles with a 266 / mg cam it gets boring.

Yeah my 998 is running a mg cam if I was keeping it na I would deffo up the cam to 276 to have that bit more of a kick

[Midas Mk1]

I don't find an sw10 (improved 286) no harder to drive in traffic than my 2.7fd MPi, agree if it's fast road you want a kick, some fun.

[Teapot]

Huey has a 286 cam in his 1380 MG Metro engine because a rebuilder thought it would be a good idea 12 years ago before I bought him. If I were starting again from scratch I would obviously study the advice given here, but I absolutely love the setup now I've got used to the 2.9 FD fitted a year ago. Hot idle at 7-800 rpm is satisfyingly lumpy, and there's adequate power from 2k. If I feel like taking off in second I can keep up with almost anything for a few exciting moments and third just goes on and on in that rather frightening but breathless "I must be doing 90 by now, oh no, it's only 65" way. Top has useful punch at 60-70 and beyond, I expect My chosen rev limit is 6k.

I'm sure it would be even better if the engine were rebuilt to top spec but I would just spend more time being terrified, which at my age isn't good.

[Cooperman]

What is the point in fitting a 286 cam which gives of its best at 6400 rpm and then set a rev limit of 6000 rpm.

That is known as 'over-camming'. It is absolutely pointless and a 276 would perform better overall.

I have to say that it is getting boring having to keep explaining how to read a cam graph and match that to the capability of the engine to sustain the rev band demanded by the cam in order to perform properly.

 

Let me just say that in order to get a 286 to work as intended you need to be revving at between 5500 rpm & 6700 rpm  and the engine needs to be capable of this without blowing up. So special pistons are needed coupled with a fully balanced bottom end, a really well flowed head, a high compression, a special distributor, a matched induction & exhaust system and a light flywheel. Then it needs a very close ratio gearbox to keep within those revs when changing up or down and a low final drive to pull away with the high 1st gear a CR box gives.

 

Of course an engine can be made to run with a 286, but it won't be able to use the cam as intended.

 

There is indeed a lot of truly muddled thinking and lack of engineering knowledge about the 286 cam.

[HarrysMini]

What is the point in fitting a 286 cam which gives of its best at 6400 rpm and then set a rev limit of 6000 rpm.

That is known as 'over-camming'. It is absolutely pointless and a 276 would perform better overall.

I have to say that it is getting boring having to keep explaining how to read a cam graph and match that to the capability of the engine to sustain the rev band demanded by the cam in order to perform properly.

 

Let me just say that in order to get a 286 to work as intended you need to be revving at between 5500 rpm & 6700 rpm  and the engine needs to be capable of this without blowing up. So special pistons are needed coupled with a fully balanced bottom end, a really well flowed head, a high compression, a special distributor, a matched induction & exhaust system and a light flywheel. Then it needs a very close ratio gearbox to keep within those revs when changing up or down and a low final drive to pull away with the high 1st gear a CR box gives.

 

Of course an engine can be made to run with a 286, but it won't be able to use the cam as intended.

 

There is indeed a lot of truly muddled thinking and lack of engineering knowledge about the 286 cam.

This is what I was trying to get at. Unfortunately, people seem to be obsessed with 'biggest is best'.

[Cooperman]

Too much reading the Mini 'comics' and not enough reading of proper engineering articles and books.

 

For rallying a 286 is a superb cam, especially for tarmac special stages on full pace notes and with the right transmission to match it and enable it to give of its best in an engine capable of pulling 7000 rpm without distress. Expect to rebuild it regularly.

 

For the road a 286 in nonsense. Who drives around at 6400 rpm all the time?

[HarrysMini]

Absolutely, I suppose it's the same people who fit bucket seats and a roll cage to a solely road going Mini.

 

It's their car though, and their decision as to what they do with it.