16 replies to this topic

[pickuptruck1994]

Basicly have anyone used these cams looking at the kent ones. But still unsure which one to get is there any difference between the 286 and the scatter one e.g torque and power wise. Cams will be going in 1275 with mg metro big valve head as a fast road car well play car for weekends :):):)
Will probs be getting it bored to next size up and also what cr are people running??
Regards
Jordan

[Deejayry]

I used to run a 1275cc A+ engine with stock bottom end, stage 2 cylinder head with rim flow valves 1.5 ratio roller rockers HIF44 carb and 276 cam, around 10.5:1 CR, it was a nice sporty engine that was easily drivable in traffic and was used as my daily drive.

 

I recently changed to a 1380cc engine with fully lightened and balanced forged steel crank, ultralight flywheel & backplate, lightened balanced & shot peened con rods, omega pistons, full race big valve head, 1.5 ratio roller rockers Dellorto DHLA 48 carb & 286SP cam and 11.5:1 CR. It is a compeletly different drive, there is little power before 3000 RPM, its not much fun to drive in traffic or even below 40mph, but when its on cam it really comes in to its element, bags of power through to 7500-8000 RPM.

[jaydee]

For a scatter pattern cam its vital to have it timed correctly and checked regularly, because its got altered timing to compensate for the different fuelling of the siamese ports head.

On a 'standard' cam you dial two cylinders in, and the other two will be 'out of timing' but its hardly to have all 4 cylinders running wrong.

If a scatter cam is wrong, then you'll loose all the power.

 

A 286 cam is a good cam for a 1275, but its really intended for competition minis, where you have to spent a lot more money in engine builds.

The 276 is still usable at decent revs, but to get out the most out of a 286, you need an high revving engine (balanced crank assembly, lightened flywheel etc..) and high revs means, that you dont have to expect it to last 100k miles.

With the 286 you need an high static CR, 11:1-12:1 a good cylinder head to ensure engine breathing and low gearing to keep the cam on its power band.

 

That said, both cams can be driven on the road, but if yours a daily drive, used in the traffic etc.. i'd consider something mild like a 266.

[Cooperman]

We continually have these questions about cam choice. What we need is a 'sticky' with a cam choice explanation and selection guide.

Basically the 286 and above are competition cams and to get the best performance from engines with them fitted it is necessary to be using well over 6000 rpm a lot of the time. This means frequent engine re-builds. It also requires a straight cut close-ratio gearbox in order to keep the engine 'on the cam'.

For a road engine the absolute max is a 276 and with this a 3.44:1 FDR is recommended, which means higher revs for a given cruising speed.

The best overall cam is undoubtedly the MG Metro or Kent 266 which are very similar and which give good power up to 6100 rpm with peak at 5500 to 5700. Torque is good from around 2500 rpm and the engine will pull smoothly from around 2000 rpm.

I run a 286 in my rally 'S' but would never consider one for a road car. My engine gets rebuilt very frequently and is fully balanced to take 7000 rpm, has expensive pistons, lightened flywheel, 11.2:1 CR, big valve fully gas flowed head, twin H4 carbs, custom distributor, 1.5:1 roller rockers, etc, etc. On the road it is horrible, but on a rally stage it's fabulous.

[pickuptruck1994]

im using a gearbox off a mg metro engine so if im right that's got the 3.44:1FDR needed for the 276, the car is basically my weekend toy but will be mostly used down the lanes and other roads need me then maybe a few track days or events when I feel like it from what I just read I think the 276 cam will probably be best for me..... I will be going roller rockers and toying with the idea of getting crank balanced and get an lighten flywheel ????. I have got a set of twin hs2 which I will probably run does anyone have an idea what mpg I could expect running them as will be doing l2b and a few other long distance events hopefully  

regards

Jordan

[Cooperman]

That sounds very good.

I wouldn't bother with the 1.5:1 rockers as you won't really gain anything. Spend the cash on a better gas-flowed head or a cross-pin diff. 

HS2's are a bit small if you want decent power and they run out of 'puff' at around 75 to 80 bhp, whereas a 276 can give just over 90 bhp with the right head and exhaust system when fitted with HS4's or a single HIF44.

A lightened flywheel is a good idea, as is a centre main bearing strap. 3.44:1 FDR should work fine.

Make sure the cam is very accurately timed in and do a 'trial build' before final machining/assembly. Set compression ratio at around 10.5:1

Fuel consumption will depend on how you drive it, but if modifying as above one might assume you will be driving it at reasonably high revs due to peak power with a 276 coming at 6100 rpm. So expect something in the region of 26 to 28 mpg, maybe slightly less around the lanes.

[pickuptruck1994]

Thats brillent thankyou so my for the much needed info. First time building an non stanard engine so all the help needed haha. Cheers for all the info again
Regards
Jordan

[pickuptruck1994]

Forgot to say someone at work said I should have a look in to bike carbs..... He was going to put them on his rover. V8 but is going down a different root now
Any used bike carbs???
Regards
Jordan

[Cooperman]

It's a lot of work to fit them and get them set up correctly. For a classic car it's probably not worth the effort, bearing in mind that a Mini is never going to be a quick car by current standards.

Stick with the twin SU set up an you'll have a true classic with period modifications which will drive nicely with the retro feel a Mini gives.

[phil hill]

I used to run a 1380 with a 276 in my old engine build.  This was a "not so slow" road build car to use Peter's expression, with 13" wheels and a 3.44 FD.  It was pretty good around town and plenty of power when giving it some more revs.

 

In a refresh rebuild I "added" 1.5 ratio rockers and IMHO it didn't work with the 276 cam in this build.  The idle quality dropped to boarderline unacceptable, the engine became more "cammy" and the benefit was only a few hp at full power, maybe 5 hp at maximum revs.  Maybe the mix of parts, compression ratio in use etc. didn't suit but to me the engine wasn't as good with the high ratio rockers as without.

 

My next engine was a more track-oriented build, 1293 with the SW10 cam from Swifttune, the 1.5 ratio rockers and 3.6 FD running on 10" wheels.  This combination with a 10.5:1 static compression is, again in my opinion, a great combination.  It is really tractable around town and has a "bearable" idle, but will go hard when you want it too.  Once you are rolling the car will happily chug along in traffic at 20mph in 4th without hunting and rocking the engine about on it's mounts unlike the previous 1380 with the 276 and 1.5 ratio rockers.  

 

Phil.

[jaydee]

There is a couple of stickies in the FAQs, but could be either that people dont read FAQs or wanted to ask opinions to members.

 

Anyhow what cam to use, what oil and what stage 1 kit are some of the most debated topics on TMF

 

Second only to jeremy kyle's thread

[racingbob]

very happy with my mg metro cam

[vx220]

Would I be right in saying cams become more tractable with megajolt?

And do 7/8 port heads make them feel milder still?

So a 7/8 porter with bike/carbs, properly mapped would be more driveable everyday (as well as more powerful) ??

[greenar]

Jordan

JUst double check what diff you have in the MG Metro gearbox. Bill Richards recently rebuilt my MG Metro engine and gearbox and I'm sure he said they had a 3.7 dif as standard as they ran on 12 inch wheels.He changed it for a 3.44 and it gave better cruising speeds and I'm still on 10 inch wheels. I'm no expert so it's not gospel but I would just double check if you're going to that effort. 

[Deejayry]

Would I be right in saying cams become more tractable with megajolt?

And do 7/8 port heads make them feel milder still?

So a 7/8 porter with bike/carbs, properly mapped would be more driveable everyday (as well as more powerful) ??

 

I would agree with your point about megajolt or similar mappable ingition systems, i use a polestar ignition system on my mini and get a smooth idle at 1000rpm with the 286SP cam, on the old engine with a 276 cam and aldon red spot dizzy i couldnt get a smooth idle much below 1100-1200 RPM.