52 replies to this topic

[Sprocket]

The older 850/ 998 springs have a lower seat pressure, almost half that of the A+ spring. Not sure how well those will work especially at the higher end of RPM

The comment on the double springs I linked to, about the nose pressure being 'FAR to much' is not justified since the quoted 200lb nose pressure is at 0.515" lift. Your cam will only give you a max lift of 0.400" with the standard 1.27:1 rockers. Noting that the standard original Cooper S springs were 160lb at 0.400" lift.

[giz]

i've got nothing to loose by trying these springs and martin was damn sure they would work. if not then i will buy a set of those double valve springs and change the head just to be sure.

[giz]

i've just finished bolting it all back together, it idles much better than it did before, it's a lot quieter and revs much smoother.
i haven't driven it yet though, i'll make a few phone calls first and see if i can get someone to follow me with a tow rope

[giz]

i've been out in it on a massive 15 mile round trip, no misfires or hesitations like the old springs seem to give the car(?) , and more importantly no snapped rockers. i've set the mixture a little better now it's at running temperature and adjusted the timing slightly as it was pinking a little up hill under load.
i'll venture further tomorrow.

Edited by giz, 03 January 2012 - 08:01 PM.

[bmcecosse]

On the spring pressure - the Cooper S had larger/longer/heavier valves - and was sold as being 'ready to compete'. That's why it had 160 lb springs - and they are longer too, so NO chance of binding up And it was fitted with a duplex chain to drive them - for good reason! .You are running a miserable standard 998 head with tiny/short/light valves - you don't need 200 lb springs! I accept they may not be 200lb at the lower cam lift you have - but they are still FAR too high pressure for your engine spec. They are simply absorbing power and wearing out the valve train. But - at least they aren't snapping the rockers so far! So - well done. It's a mystery to me how the rockers were breaking before....... A standard 940 head will make your car go SO much better!

Edited by bmcecosse, 03 January 2012 - 09:12 PM.

[giz]

i haven't put those springs on! i'm using the shorter early 850/998 springs.
a 940 head will also cost me more money due to the machining needed to make it work.
this is not a performance mini, it's a daily driver used mainly to get to work through country lanes and overtaking tractors, all i wanted was a bit more power using the parts i already had for as little as possible, which i think fingers crossed i have achieved. so far the engine has cost me £50 for gaskets and filters and £12 on springs.
a bigger valved, better flowing head will be the next step but it won't be any time soon.

[philc]

well done for sorting it out

[giz]

thanks phil, so far so good, i've done 30 more miles in it today hassle free. i'll pop to the cake shop tomorrow i think