Re: [alfa] Distributor questions

["Dean W. Cains" <dwc@xxxxxx>]

Hi Jon:

The springs should be as you've described, and as many as I've checked, I 
can't recall ever seeing a set that had stretched or worn out.  That's not 
to say it never happens, though.  The best way to check what you've got is 
to use an advance timing light and plot the curve yourself.

If you were to modify the spring(s) as you've described, you'll end up 
moving the advance curve further up the rev range (likely not what you 
want), as stronger springs will present more resistance to the centripetal 
force of the advance weights.  And, changing the springs will never change 
the amount of total advance, which is limited by whatever it is that stops 
the weights at the end of their travel outwards.  Look at the mechanism of 
the Marelli, and you'll see vertical pins that limit the travel of the 
weights, even with the springs removed.

A mid-level upgrade might be to drop in an older Marelli S103B or BA, and a 
better upgrade would be to use an (even older) Bosch 041, 044, or 045.  All 
of those are breaker-type distributors, and except for the 041 can very 
easily be upgraded to breakerless electronic ignition.  Those Bosch units 
have curves very close to what the old high-performance Shankle disty's 
had, and may have been the models Shankle tried to match.  I've got an 041 
in my '74 Spider, and it's very much better than the S103BA, but was a 
giant PITA to make breakerless.

Many of the popular Alfa parts vendors sell upgraded systems, too.  They're 
mostly using modified Bosch 009 disty's with either Crane or Compu-Fire 
electronics, and then there are the systems from Wes Ingram and Jim Steck 
that are crank-triggered, and probably wasted on a mostly stock street-use 
engine.  I'd start cheap and work my way up the scale.  Maybe find an 
S103BA, see how it feels, and then maybe upgrade it to breakerless with a 
Crane XR700 or XR3000 kit.

Regards,

Dean
Lutz, FL
'74 & '87 Spider Veloce's


At 08:22 AM 8/2/2004, you wrote:

> Date: Mon, 02 Aug 2004 02:23:12 -0700
> From: Jon Pike <jhpike@domain.elided>
> Subject: [alfa] Distributor questions
>
> Hi all..
>
> I've been driving the 77 Spider with it's stock Marelli SB166B (weakest
> curve for smog cars) distributor,
> and it's probably worn and or streched in the springs.  I was wondering
> a few things, one is how tight should
> the advance springs be?  Mine have one under tension all the time, and
> the other loose, I have no idea what it
> was like 27yrs ago..
>
> I've been told about a trick of nipping off the hook end, and remaking
> it, effectivly taking one turn out of the
> spring.  This is supposedly right for compensating for stretch, and or
> creating a better curve.
>
> The other thing,  I hear just breaking down and getting a Bosch
> distributor is a good idea.  Eaiser to find a pointless conversion kit
> if you are so inclined, and better curves, just a better part overall.
>
> So, wondering what comments I might get on this subject..   anyone tweak
> their springs,  or have experience with
> swapping distributors?  Anyone got a Bosch they want to get rid of?
>
> Thanks..
>
> Jon
> 77 Spider
> Irvine, CA
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