27 replies to this topic

[Boothy]

Hi I would like to know what cam would be best suited for my Mg metro 1300 engine?
I want to make it a good fast road mini and would like to know your history with them
and how they have performed.

Thanks Jack

[Nightrain]

The original cam is hard to beat, for a daily use engine. If you want something with a little more go your looking at cams in the 286 range. But to get the best out of such a cam in a modern mini, you really need to be considering you gear ratios and final drive.

A word of advice though, be brutally honest about how you drive and the roads you drive down !

[Boothy]

The original cam is hard to beat, for a daily use engine. If you want something with a little more go your looking at cams in the 286 range. But to get the best out of such a cam in a modern mini, you really need to be considering you gear ratios and final drive.

A word of advice though, be brutally honest about how you drive and the roads you drive down !

Cheers for that. I will be using it for RWYB at drag racing and not driving at 30 every were. As for the roads bit on bypass and B-roads.

Jack

[Nightrain]

[Cheers for that. I will be using it for RWYB at drag racing and not driving at 30 every were. As for the roads bit on bypass and B-roads.
Jack

It'd help if we knew your current spec, but if the above IS the only type of driving you do. You want to be looking 296/MEDS AGSP/STR930 type of cam. At least a cooper S close ratio helical box and a 3.7 final drive.
But bear in mind, 70mph will be at around 4500rpms, so no good on motorways. But B roads will be a scream.

[bmcecosse]

Unless doing extensive other engine mods - I would stick with the excellent MG Metro cam ! It's by far the best cam ever fitted as standard to any factory engine. If you are willing to modify the engine for running at higher rervs - then the old BMC 544 (or some of it's many copies) is an excellent cam - with 286 timing it retains good torque but still gives plenty at the top.

[Boothy]

Thanks guys. My current spec is basically a stage 1 with a good lcb manifold and a HIF 44 carb.

Also are roller tip rockers worth the money

Cheers Jack

Edited by Boothy, 03 October 2009 - 07:41 AM.

[Adcuz]

Also are roller tip rockers worth the money

No

[mini7boy]

Unless doing extensive other engine mods - I would stick with the excellent MG Metro cam ! It's by far the best cam ever fitted as standard to any factory engine. If you are willing to modify the engine for running at higher rervs - then the old BMC 544 (or some of it's many copies) is an excellent cam - with 286 timing it retains good torque but still gives plenty at the top.

Roy, I have noticed in several places where you claim that the 544 and 286 cams have the same timing specs, yet in checking the Vizard book and Kent website,
I see no indication that these two cams are the same profiles. Can you please disclose where you have seen timing specs that show these cams equivalent?

I know that the use of different checking heights can make a difference, but I didn't see any evidence of that in this case. The LCA is also different, according to Vizard.

Edited by mini7boy, 03 October 2009 - 12:04 PM.

[Cooperman]

The 544 times as follows: 34/74 69/36 with a lift of 0.387
The 286 times: 34/66 71/39 with a lift of 0.380" in and 0.400 ex

Duration is 288 deg with the 544 and 280 deg in and 290 deg ex on the 286

Not very different in overaqll terms and on a rally car it would be hard to tell the difference.

Both very nice cams in fact with strong power from about 4500 and good torque from about 4000.

[mini7boy]

The 544 times as follows: 34/74 69/36 with a lift of 0.387
The 286 times: 34/66 71/39 with a lift of 0.380" in and 0.400 ex

Duration is 288 deg with the 544 and 280 deg in and 290 deg ex on the 286

Not very different in overall terms and on a rally car it would be hard to tell the difference.

Both very nice cams in fact with strong power from about 4500 and good torque from about 4000.

my remarks would assume that the same checking heights are used for both cams.

aside from the fact that both cams could have very different opening rates despite timing specs that are similar,
the intake valve on the 544 cam is open 8 degrees later than the 286 and the exhaust on the 286 is open for 5 degrees longer.

these cams are at best similar, but hardly the same. I suspect that the real difference shows up in opening rates, but
we have no data to support that idea.

[Cooperman]

I don't have the ramp data, sorry.
All I can say is that when I went from a 544 to a 286 I didn't notice much difference and the max bhp figure was very similar. Can't give the torque figures and when I changed cams it was because I was going up one bore size and the cam lobes on the 544 didn't look too 'healthy'.
My discipline has always been rallying, and the above cam change didn't seem to make any difference to how the car went on tarmac or gravel. In a back-to-back test on twisty tarmac for a Mini World article, my car with a 286, twin H4's, a 3.9 FD and a x-pin diff was quicker than a similar car with a 649, 45 DCOE, 3.9 LSD, etc, and that was the case when we drove each others cars as well. In a straight line it was a differnt matter with the other car being about 0.5 secs quicker over a 1/4-mile. However, for circuit racing where a couple of bhp difference can give a better result it may be a different matter.
Fit what you are most comfortable with. Even on the old Works rally cars different drivers liked different cams. Timo always liked the 649, even on gravel, whilst the others tended to prefer the 544. On gravel the 510 was quite popular. Even with those differences, it was not always the same driver who was quickest.
It's all a compromise.

[mini7boy]

I don't have the ramp data, sorry.
All I can say is that when I went from a 544 to a 286 I didn't notice much difference and the max bhp figure was very similar. Can't give the torque figures and when I changed cams it was because I was going up one bore size and the cam lobes on the 544 didn't look too 'healthy'.
My discipline has always been rallying, and the above cam change didn't seem to make any difference to how the car went on tarmac or gravel. In a back-to-back test on twisty tarmac for a Mini World article, my car with a 286, twin H4's, a 3.9 FD and a x-pin diff was quicker than a similar car with a 649, 45 DCOE, 3.9 LSD, etc, and that was the case when we drove each others cars as well. In a straight line it was a differnt matter with the other car being about 0.5 secs quicker over a 1/4-mile. However, for circuit racing where a couple of bhp difference can give a better result it may be a different matter.
Fit what you are most comfortable with. Even on the old Works rally cars different drivers liked different cams. Timo always liked the 649, even on gravel, whilst the others tended to prefer the 544. On gravel the 510 was quite popular. Even with those differences, it was not always the same driver who was quickest.
It's all a compromise.

Nobody has the ramp data unless they collected it themselves. It would also be difficult to describe the opening rates numerically because it would take a
number of data points to really convey the rates in such a way that they could be understood by most folks. It's not like one could provide a
single number, as is done with duration or lift, to express the opening rate for a valve. That's because the rate changes during the period
that a valve is opening.

My intention was merely to point out that the 544 and 286 are different cams and should not be thought of as the same. Given the many years
between when each cam was designed, it's pretty unlikely that they would have been designed similarly. Ideas about A-series cam design have changed significantly
in the decades since the 544 was designed. All one has to do is read Vizard to get an idea how times have changed. Cams like the 544 were never
designed to run with 1.5 rockers, for instance, whereas many of today's cams were designed to exploit higher lifts and more rapid opening rates.

[Nightrain]

The thing is, all the criteria has changed since the sixties fuel/emissions etc. When vizard designed the 286, did he start from a blank canvas ? No he did not and would have been stupid to have done so, throwing away all the years of development BMC had already done.
He took the fast road/rally 544 and looked for ways of improve it, using much more modern technology/developments.

Cams as far as we're concerned on here, can still basically be classed in around three categories.
Road up to about 250 degrees inlet timing.
Fast Road/Rally from 250 degrees up to about 290 degrees inlet timing.
Full Race 290 inlet timing upwards.

So really the 544 and the 286 fall into the same basic class, all modern tech has done is blur the borders slightly, so one mans full race cam is another's fast road cam. Mind you pretty sure that was always the case anyway, as mentioned above. Timo proved this on the '67 RAC iirc. When everybody else opted for the standard 510 S cam, but he stuck with the 649.

[mini7boy]

The thing is, all the criteria has changed since the sixties fuel/emissions etc. When vizard designed the 286, did he start from a blank canvas ? No he did not and would have been stupid to have done so, throwing away all the years of development BMC had already done.
He took the fast road/rally 544 and looked for ways of improve it, using much more modern technology/developments.

Cams as far as we're concerned on here, can still basically be classed in around three categories.
Road up to about 250 degrees inlet timing.
Fast Road/Rally from 250 degrees up to about 290 degrees inlet timing.
Full Race 290 inlet timing upwards.

So really the 544 and the 286 fall into the same basic class, all modern tech has done is blur the borders slightly, so one mans full race cam is another's fast road cam. Mind you pretty sure that was always the case anyway, as mentioned above. Timo proved this on the '67 RAC iirc. When everybody else opted for the standard 510 S cam, but he stuck with the 649.

saying that cams fall into broad categories is nothing like saying they are the same.

the 544 was designed for the smaller 1000-1100 Formula Jr. engines whereas the 286 was developed for the larger engines by adding lift and exhaust duration to the 544.

in his book, Vizard proclaimed the 286 to be a significant improvement over the 544 which was quite a good cam to begin with.

so, while these two cams may fall into the same fairly broad category you define, they are nothing like the same cam.

[bmcecosse]

Crikey - such a fuss! I would hope the '286' is a better cam - it's a much newer design and they would hardly go backwards. My experience is mostly with the genuine 544 - I only mentioned '286' as being the nearest modern equivalent, because genuine 544s are probably thin on the ground now - and I honestly can't believe the power difference will be at all noticeable between the 544 and the '286'.