20 replies to this topic

[sx_turbo]

hi,

right i got a mini sport mild road cam, according to minisport it's the old special tuning st510 cam, now because the gf bought it about 2 years ago, she no longer has the spec sheet, so i phoned up minisport,

mini sport gave me the specs and said it's basicly just a stock cam, and doesnt really provide any performance increase, and also proceeded to tell me not to bother timing it in and just use the stock timing.

what are your thoughts on this?

and why do they bother selling them if theres no real point in performance increase??

[mykweb]

and why do they bother selling them if theres no real point in performance increase??

Its mini sport, they are only after your £££££

Mike

[Cooperman]

Actually the 510 was not an ST (BMC Special Tuning) cam, it was the cam fitted as standard to the Cooper 'S' range from about 1964 onwards. It's a nice cam and slightly better than the standard 998 or 1275 cam, but not as good as the MG Metro or Kent 266 cam for a road engine. The 510 is quite nice in a 998 and I fitted one to a 1061 cc Mayfair with a 12G295 head a year or so ago. It was very smooth and quite 'torquey' in mid-range. certainly better than the standard Mayfair 998 cam.

[sx_turbo]

Actually the 510 was not an ST (BMC Special Tuning) cam, it was the cam fitted as standard to the Cooper 'S' range from about 1964 onwards. It's a nice cam and slightly better than the standard 998 or 1275 cam, but not as good as the MG Metro or Kent 266 cam for a road engine. The 510 is quite nice in a 998 and I fitted one to a 1061 cc Mayfair with a 12G295 head a year or so ago. It was very smooth and quite 'torquey' in mid-range. certainly better than the standard Mayfair 998 cam.

oh i see, on there website, they say it's an st cam.

any hoo,

do i go through the rigmarol of buying a dial gauge etc and timing it properly, or do what minisport say and time it as standard?

[Cooperman]

The problem with cam timing is that with the dot-to-dot method you don't know whatthe manufacturing errors (i.e. the tolerances) are on any of the components whih control the cam timing. I've timed-in after market cams and found that the dot-to-dot error has been anything from zero to 9 degrees retarded. I always use a DTI and a protractor to get it right using offset woodruff keys. The 510 should be timed in at 110 degrees ATDC, or 108 degs to allow for 2 degrees of timing chain stretch if the chain is new.
Some people say it's not worthwhile accurately timing in a mild cam like a 510, but I just like things to be right. There are 4 parts on which the machining tolerances can effect timing accuracy: The cam keyway, the cam sprocket, the crank sprocket and the crank itself. The crank is normally pretty accurate, but, especially if the other parts are 'after-market', they can be quite a bit out.

[sx_turbo]

ok cool, thats what i was thinking,

the bloke who put the cam in her old engine, didnt dial the cam in, and just used standard marks, the engine never really ran right and pinked like a *******, and felt really flat, that was with the 12g295 head.

once i adjusted the timing advance on the disi, ad used the colour tune it stopped pinking but was still really flat.

the timing chain being used is an old one thats covered 6000 miles so should be ok.

[Racer_Pete]

Slighty off topic but do you only have to allow for chain stretch when a duplex/chain is brand new? As I thought you had to allow for chain stretch every time even when the duplex has been used.

thanks.

[Cooperman]

Slighty off topic but do you only have to allow for chain stretch when a duplex/chain is brand new? As I thought you had to allow for chain stretch every time even when the duplex has been used.

thanks.

The chain stretches most during the first couple of thousand miles, after which the rate of stretch slows considerably. I cheked one and it had stretched and retarded the cam by 2 degrees after 3000 miles in my '64 'S' rally car which, admittedly, uses high revs. I believe that my 3000 miles is equal to most peoples 10000 miles in chain stretch terms, so if you time 2 deg advanced at new, it will be at optimum timing for most of its life if you change the chain at 20-25000 miles.
I hope that is logical.

[bmcecosse]

I agree - that 510 cam is not much good - hardly worth fitting ....... But if you do - then dot to dot timing will be fine for it!

[sx_turbo]

will be fitting it because it's the only cam i got,

i thing i will fit it with a dial gauge just so i can be absolutely certain it's right,

cheers people.

[bmcecosse]

There's no point 'dialing' it......... do you have the correct oil pump to match the drive end ?

[miniobsessed]

Please time it in correctly. The only time I would use the dot to dot method would be for a bog stock 850/998 with a standard cam and even then I'd still check it.

Aftermarket cams are very often 'offset' to some degree and even a 'low performance' cam profile like the 510 (sorry, is a Cooper S 'low performance'??? I didn't think so...) should be timed in correctly. Really, it does not take very long to correctly set up a cam (whatever profile it is) and on a 'low performance' engine could certainly be worth the odd bhp but more importantly the odd ft-lb of torque.

[Cooperman]

Please time it in correctly. The only time I would use the dot to dot method would be for a bog stock 850/998 with a standard cam and even then I'd still check it.

Aftermarket cams are very often 'offset' to some degree and even a 'low performance' cam profile like the 510 (sorry, is a Cooper S 'low performance'??? I didn't think so...) should be timed in correctly. Really, it does not take very long to correctly set up a cam (whatever profile it is) and on a 'low performance' engine could certainly be worth the odd bhp but more importantly the odd ft-lb of torque.

Agree entirely. I'm from an aerospace engineering background and we were always taught 'If it isn't absolutely right, then it's wrong'. The dot-to-dot timing method may well have been fine for BMC back in the 60's, but look at how some cars were better than others in performance terms when standard. Tolerance build-up is the main reason for this effect.
It is just so easy to time acurately. A protractor is pennies and a DTI is not expensive if you don't have a friend from whom you an borrow one. Offset woodruff keys are also cheap even if you buy a set of, say, +2 deg up to +8 deg in one or 2 deg increments. If a 510 am turned out to be, say, 10 degrees retarded using dot-to-dot, it would certainly lose a few bhp and probably use more fuel too.

[Cooperman]

Also, if it's an original BMC 510 cam it won't have the lobe for the mechanical fuel pump. Be worth checking this.

[bmcecosse]

But - what will the cam be 'timed in' to?? Who knows what setting will work best - slightly advanced? Slightly retarded?? Unless there is good RR access - it's a guessing game. And with a 'soft' cam like the 510 - a degree or two here and there won't make the slightest bit of difference! BMC didn't even claim any extra power from the 1275 S when they fitted this cam in place of the original AEG 148..........