41 replies to this topic

[Chris M]

I've currently got the engine out of my MPI  stripped out on the bench to fix some oil leaks & a good clean & paint up.

Whilst its in bits should I fit a new camshaft & would I get any gain out of a performance camshaft without a performance head.

My budget won't currenlty stretch to a cam & head so I thought maybe fit a cam now & then a head later as a head can be fitted with the engine in the car.

Any views or advise would be great.

[Wiggy]

I don't know what gains you'd get, but personally I think it's a no brainer to do it whilst the engine is out. You'll need a new set of tappets too. I inspected and reused the simplex timing chain, and used an offset vernier key to time it.

But it depends on your willingness, time and facilities as to whether you want to take the engine out again in the near future.

If the gearbox is original, it will likely need a rebuild, and you can consider changing the final drive ratio and fitting a cross pin diff.

My diff pin was nearly worn through at 25k, and 2nd gear would crunch on the downshift and pop out of gear at 16k.

[Carlos W]

Have a word with AC Dodd.

He’s got his own range of cams which look very impressive.

Is there a pick up on the mpi cam?

Replaced the oil pump whilst you’re on

[Midas Mk1]

SW5i, its a belter for fast road, yet totally driveable in every day use. 

[rich_959]

SW5i, its a belter for fast road, yet totally driveable in every day use. 

 

That's what I've got going in mine. Same as OP, I've kept the original head with a bit of polish/porting by the local garage and having the compression set up properly. I can always go for a 'fancy' head further down the line if I feel the need. Main thing was doing the right cam while the engine was out. Car isn't back on the road yet so I can't report back on the results. Full spec:

 

 

Swiftune SW5-07 cam kit

Swiftune Duplex Timing kit (steel/ally)

MED ST1 Clutch/flywheel

Maniflow Manifold and system

Mild head polish/port and inlet and manifold matching

X Pin Diff

Central Oil pick up

[Wiggy]

Another option is the Kent 274i. I fitted one to my S Pack MPi, and have been extremely impressed.

[Gr4h4m]

I would also keep I mind that unless you go for a custom ecu you will be limited to making the best of the performance mods as you can’t chnage the fuel or timing. The cat if required for you model to pass the mot might also need a performance version.

[rich_959]

I would also keep I mind that unless you go for a custom ecu you will be limited to making the best of the performance mods as you can’t chnage the fuel or timing. The cat if required for you model to pass the mot might also need a performance version.

 

For basic tuning I believe the MEMS jobby does a pretty good job of self tuning, up to a certain power/torque (as per the old John Cooper Conversions etc). I was advised that the spec I mentioned above is about the limit of the rover ECU being able to make the best of the mods. But I'm not basing this on experience - just repeating what others have told me from their experiences.

[Wiggy]

I have:

JCW Big valve head.
1.5:1 roller rockers.
LCB manifold and S/S exhaust.
Kent 274i cam.

3.1 or 3.2 final drive.
Cross pin diff.

I DON'T have an aftermarket fuel pressure regulator or a cone filter.

She goes very well. No flat spots, no hesitation, revs cleanly all the way to the red line. Lots more low down torque than before the cam installation.

[rich_959]

That's a good report to hear Wiggy, for similar alterations. I have no concern for the numbers, I just want it to drive nicely and reliably with a bit more poke than standard - and stay reliable.

I'm staying with the leggy final drive for the time being (some long road trips planned) so at least I'll have a like-for-like comparrison of what impact the changes have made. Though it will be going from 13" to 10" wheels. 

[Bat]

Hi,

MPi ecu does no self tuning other than when cruising at light throttle. The rest of the time it uses the map Rover gave it, it does not compensate for extra airflow as it has no way of measuring it...

Cheers

[Wiggy]

From memory, my final drive gives about 70 MPH @ ~3700 rpm. 80 MPH @ ~4000 rpm. There's a calculator on Guessworks' website. It also allows for different wheel/tyre combos.

[rich_959]

From memory, my final drive gives about 70 MPH @ ~3700 rpm. 80 MPH @ ~4000 rpm. There's a calculator on Guessworks' website. It also allows for different wheel/tyre combos.

 

Yeah, I've been through the guess works calcs. I have a 3.2 final drive on the shelf for further down the line but I'm keeping the standard one for now. 

[Wiggy]

Fair do's. I rather liked the long second gear actually. 60 MPH in 2nd was useful for overtaking.

[DeadSquare]

I've currently got the engine out of my MPI  stripped out on the bench to fix some oil leaks & a good clean & paint up.

Whilst its in bits should I fit a new camshaft & would I get any gain out of a performance camshaft without a performance head.

My budget won't currenlty stretch to a cam & head so I thought maybe fit a cam now & then a head later as a head can be fitted with the engine in the car.

Any views or advise would be great.

 

 

As a straight answer to your questions:-

 

"Should you fit a new camshaft"?   ...   You don't give the mileage and use, but not unless it is badly worn.

 

"Should you fit a performance camshaft"?   ...   NO   ...   because you have no way of telling your ECU that you have done it.

 

"Would you get any gain out of a performance camshaft without a performance head?"   ...   Yes   ...  but probably at the loss of some tractability because you have no way of telling your ECU that you have done it.

 

Having said that:-  There are people who can 'map' an ECU to match a cam, SO, if you can do a deal with someone for a cam and map, buy and fit the cam, save for the map, save again to have your head flowed and polished and provided that you don't go for too much power, take comfort that BMC/ Leyland  included quite a lot of reserve strength in the Mini "lump", to mitigate warranty claims.

 

It is a testimony to that reserve of strength, that the late Barrie Williams gave BMC their first international rally win in an unmodified showroom car (except for lights and sump guard), and Barrie didn't hang about on those Welsh special stages, either on the ground or in the air.