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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