Re: Cams, John L.

[Bob Brooks <rbrooks@domain.elided>]

jmbrodsky@domain.elided wrote:

>      Bob (rbrooks@micrelinc) said: that cams are rated for actual
>      valve lift, not lobe height.
>
>         Ummm.  Now I really have a question.  Since the factory NEVER
>      EVER can make each rocker the same, AND since you can maximize
>      your lift when you rbuild by buying the appropriate tolerance
>      rocker, you may be able to adjust the lift more or less
>      accordingly.  About a year or so ago, Petersons 4WOR did an
>      article on this very practice, and you can get sometimes up to 10
>      HP by maximizing the lift with the factory spec rockers used at
>      the limit.
>
>         Are you SURE that the numbers are valve lift, not lobe height.
>       That would also mean that the cam grinders, KNOW the factory
>      specs of each brand/model of rocker.  Aftermarket rockers are
>      also available to chenge the ratio, so what gives?
>
>      -Joel

Joel:

The numbers that you see in the catalogs when looking at cam specs are
Valve lift numbers.
And yes the cam grinders know what the lift ratio of the rockers are.

And yes again you can obtain different valve lifts , FROM THE SAME
CAMSHAFT, by varying the rocker arm ratio.

This is done on the more popular engines all the time. Think Ford, and GM.

You can also fine tune the cam lift and duration for a given engine and or
cylinder by mixing and matching valve train componenets.  This is also
done all the time, and is part of  blue printing an engine.

The closer all the bits and pcs in an engine are to the specs for that
engine, and to each other, the better the engine will run.

Remember that IH, like all automobile and truck manufactures had allowable
toleranes for every part.

This is why some engines run so much better than others, all the
tolerances stacked up the right way, and made that engine better than 90%
of the others that were assembled during the same time period.

That's why it pays to double check everything, and match everything up you
can.  You will be happier with the finished product.

Now I must really go back to lurk mode.

Bob
rbrooks@domain.elided

Micrel, Inc.
http://www.micrelinc.com