Alternatives to locked dizzy for turbo 12a?
 

Alright guys, I've posted a few times before abut my car, sooo if you don't know, I've got a blowthrough turbo 12a. Currently, I have my dizzy locked at about 15 deg. advanced, maybe a little less. Why? A lot of people told me to, saying it was the best/safest way to do it. Now, I've got another dizzy sitting around that hasnt been locked, and there's a few things I'd like to try with my timing, mainly because I don't like how the car idles with the locked dizzy. I also don't know how it effects gas mileage. Maybe someone can fill me in, I havent driven to car enough to figure it out.

First of all, I'm having a hard time understanding the advantages of a locked distributor for turbo. The people I have talked to said to lock my timing at 10-15 degrees advanced. Yet, as far as I know, the mechanical advance on the dizzy only advances the timing 14 degrees. So that leaves my max advance at 14 degrees if the timing is set at TDC at idle (I don't have the vacuum advance hooked up, so I'm not figuriing that in). If you need a little less advance, and say want your max advance to only be 10 deg., why not just retard your timing 4 degrees? I doubt it would really harm your power that much having it retarded more down low. Now, if it by chance DOES have adverse effects on your power, that little bit of retard, why don't we...

Cause the dizzy to not advance so much! So each of the weights have a little post that sticks out to top of them, which slide along a little slot. Here's an image I took from someone elses post just to show the slot I'm talking about.

http://home.comcast.net/~seanroth/dizzy003.JPG

The spring, along with the length of the slot decides how much mechanical advance there is. I've heard of some people getting stronger springs, which limits the advance, but it seem's there could be another solution, even if it was a little more involved. We could keep the springs in, and shorten the length of the slot the weights slide on. (Second picture)To do this, you'd just need to fill in a little bit of the end of the slot with jb weld, epoxy, or even do a little spot weld and file it down. Whatever you think would hold up properly. Just measure things carefully to make sure youve filled in the same amount on both sides, and youre good to go. Your timing is completely stock at idle, and it doesnt advance as much so it works well under boost.


https://www.rx7club.com/attachment.p...d=174216&stc=1
This may seem pretty unnecessary to some, but I know there are guys out there who have said they can't get their car to start and idle properly with a locked dizzy. I for one am going to give it a try, and let you guys know how it works out! Let me hear what you think of this...

hey its always good to try new things. you might wanna check out "shoptalkforum". some of those vw guys have been building turbo toys since the early 70s. the tried and true setup seems to be locked even for them, but you never know. good luck

c'mon now, 1 reply to my novel of a post? No one feels like screaming that locked timing is the only way?

good mod
 

I believe you are on the right track.
Shorter slots to limit the total advance available and stronger springs to make the total advance come in more slowly.
the idea is to be past the maximum VE point before total advance is available.
I also do not see any benefit to disabling the vacuum advance. It will only give you advance when in vacuum, so it should improve throttle response and fuel economy.
Kepp us posted on your progress.

I did this on a large ported 12A I had years ago. It liked a fair bit of advance at idle/low rpm so I welded one of the holes so it only advances 10*. Should work well in a boosted application.