33 replies to this topic

[adcyork]

Your lift figure confirms mine - I used 1.27 as the rocker ratio, but it's also often quoted at 1.25.
I suspect the reasoning for this cam is that it can be cheaply made by regrinding a standard cam - just take 30 thou off the base circle and tidy up the transition to the lobes!

Quoted from the swiftune web site: "Machining the SW5-07 from custom steel billet ensures the highest quality steel is used and deeper surface hardening achieves the superb wear performance of a race camshaft"

I also asked them about how they make their cams on the phone when i ordered my SW5-07 cam from them ages ago and they confirmed for me that they are machined from fresh steel billet and then surface hardened. They're not reground cams. I checked up on this as it was a concern i had before buying the cam.

[TimmyG]

Would a piper 255 be a long the same lines as the mg cam?

http://www.pipercams...t.php?pid=BP255

Paul.

In terms of figures, the 270i is almost the same, but with extra lift which is exactly what the mg metro cam is lacking. I'm wondering whether the figures for the 255 are a mis-print though, they are much hotter than the measured values that, i think, AC Dodd gathered for this cam, which were more in SW5 territory. Theres also another cam at the top of the list that states 256 deg duration but a power band of 3-7000rpm which is highly unlikely!

[MRA]

Sorry to Hijack Pauly!!(but I'm gonna anyway!!)

So based on the rocker ratio figures would a set of decent 1.3 ratio rockers make a difference then?

Standard rockers are 1.28:1, so going to 1.3:1 will make a difference, on a cam that lifts the valve to 0.300" on 1.28:1 rockers changinging to 1.3:1 rockers will give you an extra 0.005" of valve lift, and of course it will open and close quicker with a longer dwell....

If the old set are worn (99.99% chance that they are) then they will have lost some of their lift

Edited by mra-minis.co.uk, 03 November 2009 - 06:55 AM.

[Shifty]

Thanks for the replies guys, much appreciated.

1.3 rockers here we come!!!