i have a 12a and a GSLSE dizzy. they have different numbers stamped on the sides. i dont know if that means anything or not.

so, IS there a difference between the two dizzys or not? if so, what?

 

Supposed to be a minor difference in the advance curve. That's really all there is to it.

 

My (uneducated) reaction was they would be different but the internet suggests they are the same....

http://www.blackdragonauto.com/icatalog/rx/0081.asp

edit** 81-85 are the same anyways

 

so, nothing to make the SE dizzy less, or more, desirable? wouldnt make a difference in a 4 port build?

 

I think the 13B dizzy had slightly more total advance to it between the vacuum advance and mechanical advance. Unless you intend to use both advance devices, there's really not much difference.

 

There is a difference in the timing marks on the pulley between the 12As and 13Bs. Some of the prices for the dizzys and coil packs are just plain nuts.

 

so, the ending concensus is that there is a VERY slight difference, but not enough to make a difference?

 

Not enough to make a difference.

I've rebuilt a couple distributors and the GSL-SE has a curved advance slot while the 12A has a straight advance slot. Also the springs are different. This causes the advance to happen at a different RPM and I think the curved slot allows for a few more degrees. Maybe 5 more or something.

I swapped distributors in the GLC and I couldn't tell a difference.

 

The 12A Turbo one, IS different. It will retard timing under boost.
How much timing? Nobody really knows.

 

I wonder how hard it would be to hook up a normal dizzy to act like a 12A turbo dizzy. Let's say you're boosted (SC or turbo) and you hook the vacuum things up to manifold pressure/vacuum. As the boost rises, the diaphrams push the pickups one direction, thus retarding them. Under vacuum, they pull the usual other direction for vacuum advance.

I tried this once on my bro's SC RX-4. It showed promise, but I was in a hurry to get it to the point where he could drive it so I ditched the boost retard/vaccum advance and just left the vacuum diaphrams open and plugged the manifold. I might try it again some day.

 

I've always run a 12a dizzy and there isn't any difference.... atleast performance wise.

 

in theory there might be a little more power to be had with the dizzy that gives the most advance, but thats something you can do with either one anyways...