1380cc Cam choice Kent Cams 256, 266, Piper 255, 270, etc (1.5 ratio rockers, Stage III Head)

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B. - 02 Sep 2004 12:29 GMT

I have a 1380cc A series with an unknow race-like cam (very cammy at
tickover and little power before 3000 rpm) and standard ratio rockers
which I'm looking to make more suitable for road use (ie. swapping the
ability to rev off the dial for low down torque available from
tickover and smooth idle).

At my disposal I have an additional stage 3 Mini Sport head (35.7"
inlets, 29.3 exhausts) with 1.5 rockers which I plan to fit, but I
would also like to substitute my cam for a milder profile to suit the
engine as a whole.

Initially I'll be trying the assembled head (has to be done) and I am
leaning towards the Kent 266 but I'd be interested to hear from anyone
having any experience in road cam selection given the engine spec and
use of 1.5 rockers.

Cam valve timing comparision (inlet-exhaust):

MG 1300 16/56-59/29
Kent 256 21/53-53/21
Kent 266 24/56-61/29
Piper 255 24/60-60/24
Piper 270 31/65-65/31

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(-AD-) - 02 Sep 2004 15:01 GMT

And Elvis was sitting next to B. in the spaceship, which I thought was
kinda weird, but then they turned to me and said:

> Initially I'll be trying the assembled head (has to be done) and I am
> leaning towards the Kent 266 but I'd be interested to hear from anyone
> having any experience in road cam selection given the engine spec and
> use of 1.5 rockers.

The 266 would be a good choice IMHO.

One of my favourite fast road cams of all time for the A series. It's
very smooth and 'civilised' with stacks of mid-range torque, but still
manages to keep the power coming at high revs.

You could do with 1.5:1 rockers in a 1380, otherwise it gets a bit
strangled at the extreme top end of the rev range (though it's just about
perfect for a 1275 using standard rockers).

The 286 can be surprisingly flexible and smooth in 1380s provided that
the rest of the engine is put together with a view to keeping it
civilised (ie. split Webers, 2" exhaust and a superlight flywheel aren't
on the shopping list...) but it's still a noticeably hot cam, and will
tend to be a bit rougher than the other choices. One difference you will
notice is that the 286 makes for a really thirsty motor.

I've never really cared much for the 276 - I've only ever used this cam
once (in a 1275), and it seemed to lose a lot of mid-range compared with
the 266 without great gains at the top end. Kind of put me off using it
again, but maybe others have had more success with it.

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