It tells you the multiplication of the camshaft lift

e.g 1:1 ratio on 250thou lift = 250 thou
1.5:1 ratio = 375 thou lift

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As said above- the reduced base circle is made up for by rocker adjustment, the cam lift is the actual measured height from base to nose, minus the base circle diameter. If you get a micrometer or vernier caliper and measure it vertically then horizontally, the difference is CAM lift. That * the rocker ratio gives you valve lift (minus the rocker clearance, of course).

Note that increasing the valve lift by grinding cams will change the rocker geometry a bit. Normal valve lift is 8mm, big cams give around 10mm. As the stock rocker shapes are optimised for stock cams, really the rocker posts need `1/2 the difference' machined from the bottom. (ie 1.0mm) This will reduce the distance the adjusters need to be screwed down.
If you buy 1.5 rockers, they are made to suit hi lift cams already.

ps. I'm working on modifying `foreign' rockers to give 1.5 ratio in an A series. Should have more info (maybe some kits) in the new year.
They will be much cheaper than importing 1.5s. Stay tuned...

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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.

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Stop Licking the Dog...I Don't Care Who Started It

Cool i'll be looking to help NAV breathe better next year and it looks like doc will have my cure

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a cam grind can only make a cam "So" big,,,most of these would be street cams or mild(ish) rally cams,,,need any bigger cam & you`d have to weld the lobe up & then grind that back to make a race cam,,,or buy a billett cam

there are "to`s & for`s" ,,,/,,,"fors & againsts" in this welding up opperation,,,

some say that a Billett cam (made from solid rod & ground into a cam shape) is better than a welded up cam to make a race cam,,,but either way is ok,,,the weld is actually quite strong & you`ll find that the rest of the cam will wear out before the welded part some problems can arise around the area where the weld meets the original cam surface.

the welded cam is also much cheaper affair

& Kev,,,i`m doing the corrolla rockers, 1.5 ratio & much stronger & way too

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

i was of the impression that the lobe shape (degrees/duration) was probably more important than the lift height, as max airflow induction was more likely to be restricted by the valve not being open enough for highest flow at that time, and the amount of crossover time.
in simple terms theres more to be gained in fatter lobes than taller ones over the stock cam
any thoughts?

Keep us informed as very keen on getting a set of 1.5:1 rokcers for my beats.

I tink it will benefit from more air in = more power

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I've Got One
You've Got One
We've All Got One
What Is It



A Bloody Mini

1970 Mini K, 1380cc, 1.75 HIF SU, 30 70 Cam, 2" Zorts
1969 Mini K, Stock Standard and Orginal. (Slow as Hell)

On a 1275, I've found both more cam duration and more lift via bigger rockers will give benefit.
On a 1098 or smaller, stock lift is OK. Not much point opening small valves too far, so don't bother fitting 1.5 rockers.
Many sports cams reground these days have a bit more lift than stock (give up to 10mm valve lift with stock rockers) anyway.

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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.