[DeTomaso] Wrong cam with Webers....

[Kirby Schrader]

Smoothing out the idle is more to do with the individual runner intake.
There are no pulses 'fighting each other' in the plenum of the intake under the 4 bbl.

We've kinda' beat this up before….

The LSA just optimizes the performance.

But hey… what do I know… I run wide LSA's on the Pantera and the GT40.
They both have IR intakes and EFI.

Kirby


On Feb 7, 2013, at 7:58 PM, Will Kooiman <will.kooiman at gmail.com> wrote:

> 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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