6 replies to this topic

[Leekr89]

I'm looking to pull the engine out of my mini after MITP as the kent 286 cam and straight cut drop gears are driving me up the wall, as it mainly only gets used for car shows and thats mainly sitting in traffic, I want something that's got a fairly smooth idle which will pull well in the mid range. I've been looking at other mild camshafts (kent 266, swiftune sw5, minispares evo001, MED HT etc..) i think the RS is probably the best option for me but Ive never seen anyone run one?

Specs of the engine is a 1330, stage 3 head, hif44, stage 2 lcb, swiftune dizzy and an ultralight flywheel, I have a pair of hs4's that i may put on but i dont know if the spec of the engine will demand it, I ran a Weber 45 on it before but the low end drivability was rough.

What do you guys think? Looking at cam specs I can get an idea but it is confusing and changing it out isnt exactly an easy job!

[Zami]

During last winter engine refresh I elected to switch cams from vp3 to sw5. My engine specs are 1380, Lightened flywheel/backing plate, wedged crank, twin HS4, LCB, New electronic dizzy, big valve longman head, 10.5/1 comp. I am very happy with the cam change as the mid range power is strong and with the electronic ignition it starts right up with no choke and idles smoothly.

[Cooperman]

I run a 286 in my very full-on Cooper 'S' rally car, but like you would not like one in a road car. as for the SC drops, I also removed mine as they were simply horrible.

 

With regard to road cams I have view with which many disagree. Unless you are chasing say half-a-second per lap or a couple of seconds per mile when driving flat out, you are not likely to really notice much difference between the mid-range cams. Those making and selling these cams will disagree and will talk about a few more bhp or lbs-ft at certain revs, but in the end it is largely down to the quality of the gas-flowed head and the accuracy of the engine building which makes for a really nice engine.

 

I have used the Kent 266, MG Metro, Evo001, Kent 276, BMC510, BMC544, BMC649 and BMC731 cams over the many years I have been working on and rallying Minis and for a nice road car I really do like the 266/MG Metro cam (they are very, very similar). When combined with standard gear ratios and a 3.44:1 FDR the end result is a brisk and driveable car with good road manners and smooth power from around 2000 rpm up to 6000 rpm. The torque band is broad and huge revs are not needed to make progress on normal roads.

[OzOAP]

What is your compression ratio?
You don't want much, if anything over 10:1 with them cams.
I would recommend Piper 255 with 9.75/10:1

Edited by OzOAP, 17 August 2019 - 09:38 AM.

[carbon]

With regard to road cams I have view with which many disagree. Unless you are chasing say half-a-second per lap or a couple of seconds per mile when driving flat out, you are not likely to really notice much difference between the mid-range cams. Those making and selling these cams will disagree and will talk about a few more bhp or lbs-ft at certain revs, but in the end it is largely down to the quality of the gas-flowed head and the accuracy of the engine building which makes for a really nice engine.

+1. I would like to add to Cooperman's comment - my experience with the MD266 in a 1293 indicates that the amount of lift at the valve has a very significant influence on the feel nad performace of a road engine:

- standard A+ sintered rockers (? valve lift) gives nice steady idle, but felt strangled above about 5000rpm

- forged S rockers with offset bushes (about 8mm valve lift) changes idle, much better mid-range torque

- Minispares '1.5' forged rockers (about 10.5mm valve lift) fussier at idle but really opened up mid-high range

So would suggest choosing cam profile and rockers as a package to get the desired valve lift and performance.

All of above is with twin HS2s, and I am pretty sure these are not the weak link.

[Cooperman]

I have once used a Piper 255 and it worked well. 

In reality there is little to choose between those mid-range cams. It often comes down to the ability of the head to flow sufficient mixture in and out of the cylinders and a few thou different lift at slightly different valve timings won't make a noticeable difference on a well-built engine.

There are those who will claim that a xxxx cam will give a huge advantage over another cam which gives peak power and torque at similar revs, but on-the-road any actual small differences (there will never be a big difference) will not be noticed. What will be noticed is a different final drive ratio.

 

Let me give an example. A few years ago I built a 1990 Cooper as an Endurance Rally car.The regs specified standard engine & gearbox. I re-bored it to the max allowed which was +0.060". The combustion chambers were 'cleaned up' and the inlet tracts had the valve guide bosses slightly re-shaped (not so that a scrutineer would notice!). An MG Metro cam was fitted (standard in a 1990 Cooper - right?),  duplex timing gears were used with offset woodruff key to get the cam timing spot on. The inlet manifold was cleaned up and smoothed, the HIF44 slightly modified, an Aldon custom dizzy was fitted. RC40 exhaust system was used to keep it quiet. Head was skimmed 0.027" and block was decked to bring the 21253 pistons right to the top of the block. I did a few other very small tweaks, fitted a pre-verto flywheel and a set of original ratio Cooper 'S' gears with a 3.4:1 FDR. It gave 84 bhp at 5700 rpm on MASS Motorsport's rollers. It was brisk and very easy to drive with wide torque and good power at 5000 rpm plus. In fact I just bought this car back and it is now being re-restored, but this time it will have twin HS4 carbs on a flowed and matched inlet manifold. I shall stay with the MG Metro cam as it just so 'friendly'.

[OzOAP]

I have once used a Piper 255 and it worked well.
In reality there is little to choose between those mid-range cams.

Very true. I use the Piper255 because of the manufacturing quality, rather than any performance gains compared to others.
They run at a 0.012 tappet clearance, so quiet in operation and kind to the rest of the valve train.