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Quick timing question

Old 07-16-18, 02:52 PM
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Quick timing question

Quick Question on timing with a rotary.. (20B I this case but guess it makes no difference)
Am I correct in thinking idle timing is usually up around the 5-10degs area. Should it then rise from idle until peaking out or is it common for it to drop before rising?
I ask as on my microtech I have got 7degrees in for 500rpm (idle) 0degs at 1000rpm, then 8 degs for 1500rpm and up. Hopefully image below. I think I added in timing at the 500rpm line originally to try and help engine pick back up to the idle cell which is 1100rpm. However I have since realised that with a working TPS the idle value of 7degrees is used for the timing. Regardless of idle rpm. I guess I could maybe add a couple of degrees in the high vacuum region to have the same effect?
I had a realisation the other day that this drop in timing at 1000rpm could be the cause of a couple of little on and off idle gripes I have been trying to solve.
So, I could do with a picture of idle area timing values and whether adding a bit in vacuum has any benefits before I just go ahead and fiddle!
Engine is standard porting (13B exhaust sleeves) and single turbo with 875cc primary injectors. As I gather porting would likely have an impact on the answer.

Thanks in advance!
Leeroy_25 is offline  
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