[DeTomaso] Wrong cam with Webers....

Will Kooiman will.kooiman at gmail.com
Thu Feb 7 20:58:43 EST 2013


I have posted this before, butŠ

I ran my car with a CompCams 282S and currently with a 294S.

These are old school solid lifter cams with "mild rough idle" and "rough
idle" descriptions.  I don't have the specs handy, but they are on a
106deg lobe separation and they have a lot of overlap.

My car had the usual mean Pantera idle with a Holley.  When I switched to
Webers, the idle completely smoothed out.  I can't imagine it getting any
smoother with a wider lobe separation, and to be honest I don't want it
smoother.

I haven't run it hard (on a dyno) to watch the reversion, but I plan on it
once I get the car together.

My point is that I disagree that a wide LSA is needed with Webers to
smooth out the idle.  I am sure that it helps with reversion and may make
more power, but how much smoother can it get?

--
Will





On 2/7/13 8:35 PM, "MikeLDrew at aol.com" <MikeLDrew at aol.com> wrote:

>Hi guys,
>
>Here's a great video by an engine outfit in England that built a motor
>for 
>a race Pantera.   I *think* it was for the yellow factory Gr4 that was
>converted to Gr5 spec, although it might have been for the red Gr3
>converted to 
>Gr4 spec (#5855).   The latter car never really ran properly.
>
>Anyway, the interesting thing about Webers is that they demand an
>unusually 
>wide LSA (lobe seperation angle) of 112-115 degrees to work properly.
>This engine was probably fitted with a very radical narrow LSA cam
>engineered 
>for a big single-plane intake, which has completely different
>requirements.
>
>They got a ton of power out of the engine, yes (I suspect it's a big-time
>cheater stroker).   But, note the effect of the narrow LSA--ungodly
>amounts 
>of reversion, and a potentially lethal cloud of fuel vapors hanging over
>the 
>mouths of the carbs.  Years ago, I saw the Adler's Gr5 Pantera literally
>catch on fire in the pits at the POCA Fun Rally track event, because this
>fuel 
>vapor soaked the air filters, and then it backfired on startup and set
>the 
>filters on fire.   Webers have lots of fiddly brass jets that will melt
>at 
>low temperature, and it doesn't take long for an air cleaner fire to lead
>to a 
>Weber meltdown, and molten metal that runs down into the cylinders is
>never 
>a good thing.
>
>Anyway, check it out....
>
>http://www.youtube.com/watch?v=JRdwWgSGqvc
>
>With Webers, wide LSA is your friend.   It really smoothes the idle out
>and 
>removes much of the radical nature of a powerful engine, making the car
>sound quiet and docile by comparison.   But boy, will it go!
>
>Mike
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