EAB wrote:
drmini in aust wrote:
1.5 rockers will give you more mumbo above 5000rpm, but you will get more midrange oomph without them.
what kind of differences are we talking here? at the moment my mini runs out of grunt past 4700rpm. i'm after a nice smooth power curve all the way up with most coming on past 2000ish as thats where i spend most of my time.
I was thinking of putting it together myself. I've pulled apart and put together basic engine stuff but not something this size, i'm fairly confident about it but is this a good idea or not? also i want to do some porting myslef as an exersise. i've got a spare head (a bit of surface rust but good to practice on i think. has anyone done this themselves?
at the mo from peoples advice i'm dropping the roller rockers.
1.5:1 rockers for an A series were originally invented by Speedwell back in the 60s to give some of the benefits of fitting a sports camshaft, without the hassle of changing it.
Whilst on a stocko cam they do help, you will get far better torque and power by changing the cam and sticking to stock rockers.
1.5s are really not needed on a 1275 unless you are looking for power above 6500 rpm.
Putting 1.5s in with (say) a 270° duration cam gives it another kick from 5000 up, but as I said you sacrifice a little down low and in the midrange.
Best cam about if you want good power (and some revvability) is an RE13, IMO.
But of course, I'm biased...
Having said that, I've owned road Minis with BMC's 731 and 544 grinds, Waggott 20/60, Bert Jones 30/70, Camtech VP3 (619) and 631, Wade/Tighe 104, and Russell Engineering RE13 and RE282(NLA).
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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.
