9 replies to this topic

[D 'n A]

Hi all,

 

My wife has had her 1992 Rover Cooper for almost 20 years now, and at one point the engine was 'replaced' for another one due to an piston ring failure. This was before we knew eachother. The Cooper was stored for 6 years, and now has new MOT, so we enjoy driving it again.

 

I said 'replaced' as this was not a straight engine swap. The block is currently a 12A2DF75 which is a regular SPI block. However the car is still carbed, so HIFF44 it has the cast 'LCB' style manifold and Rover alu intake manifold, so the old hardware is changed to the new block. 

 

However I do not know if they changed the cilinderhead and camshaft, which where higher compression and had a different profile as it was a Cooper engine.  As the swab was done by the most well known Mini specialist in Holland at the time I reckon that he made sure the engine was in the same spec, but we cant tell for sure with the engine in the car.

 

So a question for the people with endless Mini knowledge. Could you tell the difference in camshaft profile while driving the car? So does the Cooper cam pull from an to a certain RPM which is noticeable different from the stock camshaft. Or is the powercurve nearly the same, only more powerfull across the range?

 

I'm currently waiting on a Maniflow stage one kit with stage 2 lcb and RCM, so will be taking it to a dyno in a month or two, but I would really like to know how to spot the difference between the cams.

 

Thanks in advance,

 

Dennis

[PeterG]

If you have a mechanical fuel pump mounted on the back of the block you do not have an SPi camshaft. The SPi camshaft hade the fuel pump lobe removed.

If you have the engine temperature sensor on the front of the head bellow the thermostat you most probably do not have an SPi head. The Spi head would have to machined to fit a conventional temperature sensor as in SPi form it used a sensor in the SPi intake manifold read by the ECU.

 

Hope this helps. (I converted my Spi to HIF44 adding an electric fuel pump and I machined the temp sensor hole. I'd be interested in the cam differences as I'm still running the Spi cam)

[D 'n A]

Hi Peter,

Thank you for your reply. I found some contradicting info on the fuel pump lobe, some sources say it got removed for the MPI engines and the SPIs still have them. I have a mechanical pump and I have the temperature sensor, so that all sounds positive.

I dont have the info on hand but I believe the Cooper camshaft had Cooper997(?) Duration on the intake and Leyland special tuning 731(?) Duration on the exhaust. Combined with the higher compression ratio the engine was quoted 63hp or so.

I also found the Cooper cam have the peak HP at 5700rpm in stead of 5.300. So I will have to rev it to find out.

I'm waiting on parts now, so check in a week or so and report back as I always hate when topics end without any feedback;)

Cheers,
Dennis

[D 'n A]

I had no time to test the car yet. My shift stabilizer bush was worn out and when I touched it when I replaced the gearbox seal I the last rubber fell out and it would not shift into 2nd and 4th anymore. So had to take the exhaust out to replace this.

Been waiting for over a week for my new exhaust as I wanted to replace it anyway.

I did find out my cilinderhead has location rings on the inlet manifold, so it still might be the original big valve head as only MG heads seem to have this.

How do you fit regular stage one inlet manifolds to a MG head? How do you fill up the ring gap the easy way? I would assume not filling it up will cause issues with the flow. I'm thinking of turning down the rings in a lathe. Anyone knows?

Dennis

[Spider]

The Profile of the Cam is the same as those fitted to the 1100, 998 Cooper, MKI & MKII Cooper S, 1275GT and many other Engines in the family. In these particular engines though, the Cam Timing was advanced 4⁰.

[D 'n A]

The Profile of the Cam is the same as those fitted to the 1100, 998 Cooper, MKI & MKII Cooper S, 1275GT and many other Engines in the family. In these particular engines though, the Cam Timing was advanced 4⁰.

Hi Spider,

I cannot run the car until the new exhaust is fitted but I happen to made a video last time I ran the car, the rev counter wasn't captured all the time but the engine seems to run strong to 5.500rpm with no real signs of it being over revving. It seems it ran out of power before 6000rpm I'm not sure if this equates to a stock cam or the cam that should be fitted to the car originally. I believe stock cams peak at 5200, and are done by 5500? I've been out of the Mini tech for the last seven years, so have to refresh my memory

[D 'n A]

I just took my head off. The head has location rings and rimflow exhaust valves. I think this is the original cooper head as I seem to remember normal 1275s dont have the rings. And as it does have a temperature sensor hole zi doubt it's a SPI head. Valves are 33x29

The nr 4 piston seems to be more wet and oily. Others are bone dry. Does this indicate an issue with the piston rings? Or could it also be leaky valve seals? The inlet valve is also darker and oily where the ones on the other cylinders are bone dry.

The sparkplugs are all dry and grey-ish. The exhaust valves are also grey.

I will be putting the car on a rolling road to set up properly when it's back together.

[Spider]

 

The Profile of the Cam is the same as those fitted to the 1100, 998 Cooper, MKI & MKII Cooper S, 1275GT and many other Engines in the family. In these particular engines though, the Cam Timing was advanced 4⁰.

Hi Spider,

I cannot run the car until the new exhaust is fitted but I happen to made a video last time I ran the car, the rev counter wasn't captured all the time but the engine seems to run strong to 5.500rpm with no real signs of it being over revving. It seems it ran out of power before 6000rpm I'm not sure if this equates to a stock cam or the cam that should be fitted to the car originally. I believe stock cams peak at 5200, and are done by 5500? I've been out of the Mini tech for the last seven years, so have to refresh my memory

 

 

That's pretty much what I would expect.

By advancing the Cam Timing, it gives the engine a little more power at low RPMs but runs out of breath sooner higher in the RPMs. The stock cam at the 'earlier' timing will go in a stock 1275 to about 6000 - 6200-ish.

[D 'n A]

The Profile of the Cam is the same as those fitted to the 1100, 998 Cooper, MKI & MKII Cooper S, 1275GT and many other Engines in the family. In these particular engines though, the Cam Timing was advanced 4⁰.

Hi Spider,

I cannot run the car until the new exhaust is fitted but I happen to made a video last time I ran the car, the rev counter wasn't captured all the time but the engine seems to run strong to 5.500rpm with no real signs of it being over revving. It seems it ran out of power before 6000rpm I'm not sure if this equates to a stock cam or the cam that should be fitted to the car originally. I believe stock cams peak at 5200, and are done by 5500? I've been out of the Mini tech for the last seven years, so have to refresh my memory

That's pretty much what I would expect.

By advancing the Cam Timing, it gives the engine a little more power at low RPMs but runs out of breath sooner higher in the RPMs. The stock cam at the 'earlier' timing will go in a stock 1275 to about 6000 - 6200-ish.

I never knew that about the engine in my wifes Mini. Funny how this explains a lot. I always told her I thought there was something strange with her engine, I always thought it ran out of breath to soon.

To make things worse, my wife once had a 2inch DTM exhaust fitted, which won't help performance all to much either especially as it's never been setup at a rolling road afterwards.

I'm guessing the car will drive really nice when where done fitting good parts as that seems to be a pretty good camshaft for the road

[D 'n A]

I've now replaced the 2inch DTM and the Catalytic converter with an Maniflow road RCM exhaust with twin centre exit.

I pulls much better now. Its definitely more powerful in the top end and runs out of breath somewhere around 6.500. Obviously the peak power comes on earlier. I'll be making a video off the difference in performance.

Most of all its way more quieter. The DTM is just loud all the time wich is not what we want anymore.