HEI type distributor question

[FNG]

Hey guys,
I found this distributor on ebay but didn't understand the discription about 'aggressive curve spring & weight system' if it has a vacuum advance? I thought it was either/or not both. I want to run a HEI type distributor and this seems like a good deal just don't want to spend $100 on the wrong part.
Here is the discription.
This is a NEW High output street strip distributor. It has a 50,000 volt coil , High output module and an aggressive curve spring & weight system .This is a vacuum advance model (none computerized). Color of cap may vary. This fits 302 SBF Small block ford
Here is the link.
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2469141658&category=33690

Thanks for the help.

 

[Jeff427]

It is actually normal for them to have both. The vacuum advance can only do so much, so where it leaves off the cetrifical (sp?) advance takes over (so to speak).

 

[Quick and Dirty]

The mechanical advance changes with RPM. The higher the revs, the less time it has to burn, so the fire has to be lit earlier.
The vacuum advance changes with throttle position. Low throttle means low cylinder pressure, which means the fire has to be earlier.

 

[FNG]

Thanks, I think I understand.
So, next question, is it a good distributor for a trail/daily driver?
Anyone have any experiance with one of these?

 

[Case]

Dont get zapped by that coil. It will really really really hurt. I did it once, just to know what it felt like(man did that sound stupid). I figured that i want to know so if it happened later by accident it wouldnt suprise me as much. less likely to get hurt.

 

[Skuzzlebutt]

It looks like a DUI dizzy to me. It's basicly a standard chebby upper part with a custom base/shaft to fit it into a 302. $99 is an excellent price for one of those, I think they're normally around $250(?). It's supposed to be a good/easy upgrade over stock Ford stuff.
Down sides? I think they are ugly. (maybe 'cause I think all chebby stuff is ugly) They are larger so you may have problems fitting it with an aftermarket air cleaner, I recall someone saying he had to trim a hood brace to fit his.

Do a Google search for Davis Unified Ignition (DUI) to find out more.

I had a DUI in my Bronco once, but that was something completely different

 

[FNG]

I get and let you guys know how it works. Thanks for all the help everyone.