New build, engine wants more ignition timing, but I'm scared of knock....

[youztheclue]

I have a 123 distributor with a Bluetooth app I can set any timing I want.

engine specs: l26 N42 head new stock bearing and rings.

Schneider stage 3 460 lift 280 dur. timed 5 degrees adv to spec

dual weber 32/36 dgv, I have a jet kit but need to get my o2 sensor working

pacesetter headers 2.5in exhaust

really good ignition components

kameari twin idlers and adjustable cam gear

3 core rad with dual 12 in fans for cooling. heat shielding everywhere.

a video of it running 

 

 

Edited March 19, 2022 by youztheclue

[Zed Head]

An N42 on flat tops will be up there, higher, in CR.  But, usually, full timing is in by 2500 RPM, so you might be a little bit cautious.  Your MAP curve (vacuum advance) seems a bit odd also, you might look at some examples from the FSM to see what Nissan does.  @madkaw has done some tuning on performance engines, as well as @Diseazd and other that I can't remember right now.

These are for 1973

 

 

[youztheclue]

Thanks Zed here is a updated timing chart.

[madkaw]

WHOA ! 
you don’t want that much vacuum advance( map curve) added on top of your base timing . You have your numbers reversed  . With speed density system the kpa increases with load . So instead of adding timing during cruise( lower kpa) , you are adding during timing during heavy loading 

[youztheclue]

Madkaw I did add the extra 10 degrees but the kpa is the same as the chart. So your saying I should do more like 8-4-0 not 0-4-8 

Edited March 20, 2022 by youztheclue
Added picture

[youztheclue]

I played with the timing more today it smoothes out more on this tune. It does seem to be 2 degree retard in reality so I'm going to check tdc mark for the 4 time. And re zero the dizzy. Example: set steady 10 degrees read 8 steady 14 read 12 with the gun

[Zed Head]

Have you studied the factory curves?  Vacuum advance disappears pretty quickly, and it's only vacuum (pressure based).

Does the software allow you to change units?  It will make things easier.  There are conversion charts.  I'd match a factory setup and then tune from there.

https://www.vacuum-guide.com/english/equipment/conversion_pascal_bar.htm

https://www.engineeringtoolbox.com/vacuum-converter-d_460.html

[youztheclue]

This should the stock configuration with a little more timing up top.

Edited March 22, 2022 by youztheclue