I too always used the rule of 9. Takes all worries out of the cam design. Good
comment of the ramps being long on some designs, that was another thing I liked
a lot.
---- Larry Young <cartravel@pobox.com> wrote:
=============
Ok, I'll jump in and try to make this way too technical. Both methods
are using the fact that the cylinder "mate" has it's lobes 180 degrees
apart. The rule of 9's is a bit more explicit, because it identifies
the exact lobes which are 180 degrees apart. For a 110 lobe separation
and taking the first lobe to be 0, the other lobes are at angles of:
0, 110, 20, 270, 90, 200, 290, 180
You can see that when lobe 1 is at zero lobe 8 is at 180 or exactly
opposite. Since two of the lobes are within 20 degrees of each other,
you might as well set those at the same time as Jim and Steve suggest.
Mark is setting the valves when the cam is split between intake and
exhaust centers. When the first two lobes are at +55 and -55, he would
set the last two lobes, which will be 55 degrees on each side of 180. I
have a small concern with this method, because some lift curves can have
ramps that extend 110 degrees are more from the centerline. Adding that
to the 55 gives you 165, which gives an allowance of 15 degrees for
error. If you're going to use this method, you need to make sure your
cam doesn't have long ramps. I use the other method for this reason.
Larry
Gt6steve@aol.com wrote:
> Now's the opportunity for the "Great Rocker Debate". Seeing as how we
> missed "Is it Vintage" this winter?
>
> I adjust as Jim mentioned, Chuck adjusts on the rock as Mark says.
>
> Pro's and cons?
>
>
> In a message dated 3/15/2010 10:07:03 A.M. Pacific Daylight Time,
> mark@bradakis.com writes:
>
> Bobby Whitehead wrote:
>
>> We'll we're are a three Triumph car family, two race cars now. The GT6
>>
> and now
>
>> a 1965 Spitfire we bought from Mac out in L.A.
>>
>>
>>
>>
> Nice.
>
>
>> and I need the valve adjustment sequence as I do not have a shop manual
>>
> yet.
>
>>
>>
>
> Normally the way I do valves is turn the crank until the intake and
> exhaust for
> some cylinder are 'on the rock' where the exhaust is just about closed
> and the
> intake just starting to open. Then I adjust the valves for that
> cylinder's mate.
> On the Spits that would be cylinders 1 & 4 and 2 & 3. If you follow the
> firing order it goes fairly quickly.
>
>
> mjb.
>
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