Ausmini
It is currently Fri Mar 29, 2024 11:06 am

All times are UTC + 10 hours




Post new topic Reply to topic  [ 2 posts ] 
Author Message
 Post subject: Vacuum Advance Curves
PostPosted: Tue Aug 20, 2019 9:32 am 
Offline
998cc
998cc
User avatar

Joined: Fri Feb 18, 2011 4:21 pm
Posts: 644
Location: Sydney, NSW
Hi everyone,
I recently installed a 123 Tune+ distributor in my Mini K. It is an otherwise bog stock 1098 with a 1.25" SU in very original condition.

While I've found the standard curve as programmed with the distributor to be functional (indeed, it already performs better than standard points and condenser ignition), I wonder if I could see some improvement by customising the vacuum advance curve.

Does anyone have any experience with custom advance curves (whether in the 123 unit, an accuspark blackbox or by other more traditional methods)?

I would appreciate some suggested curves to experiment with that might better suit the A-Series engine rather than just what came out of the box in the 123 (which is designed to work with all manner of 4 cylinder engines from BMC, VW, Alfa Romeo etc).

Cheers,
Tom.


Top
 Profile  
 
PostPosted: Fri Aug 23, 2019 11:19 am 
Offline
Yay For Hay!
User avatar

Joined: Wed Sep 08, 2004 9:27 pm
Posts: 15861
Location: Wodonga - Vic/NSW border
Vacuum advance is an economy device - as you close the carb butterfly the amount of vacuum in the manifold increases, and the vacuum advance mechanism in the distributor advances the timing. Advancing the timing allows the engine to make the same power with less fuel but is very likely to have pre-ignition under any load... but when there is load, your foot opens the butterfly and the vacuum advance mechanism retards the timing again.

So, you can't get the engine to "perform" any better by playing with the vacuum advance, but you may get a little bit of fuel economy improvement

For reference, my engine runs well with 39° at full load (100kpa) from 2700rpm up, and 47° at full vacuum

_________________
did I tell you that I won a trophy?


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 2 posts ] 

All times are UTC + 10 hours


Who is online

Users browsing this forum: No registered users and 20 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  

© 2016 Ausmini. All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.