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502 Posts
Discussion Starter #1
Finally I got my timing data

RPM Timing
0 0
1000 10
1500 15
2000 20
2500 23
3000 25
3500 30
4000 30
4500 35
5000 35
5500 35
6000 35

I guess this is to much advance for a turbo car.
I tried connecting the vacuum advance to the manifold so it always has vacuum, and then i set initiall timming again to 10BTDC, this way the vacuum advance is always advancing to stock timing and when boost starts it retards 10. It was only a test, but i found out that the detonation i was hearing was less now, then i tried the same thing with initial timing at 5BTDC and the car was slower at low revs, but didnt have any trouble at high revs and couldnt hear any detonation at all. So i guess the engine liked to retard about 15.
This was just a test, but now its clear i have to do something with my timing, ill have to make some device that advances normally with stock timing untill boost starts and then retard about 15 which tells me that max advance with the data above will be about 20btdc with boost if i dont step hard on it it will work almost like stock.
What do you guys think?
 

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3 bar MAP
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1,381 Posts
fwiw, every motor is different and ign should definitely be tuned on a dyno for max power and motor reliability. there are a lot of factors that determine optimum timing. retarding or advancing ign is going to effect the trq output of the motor...the only way to measure the effect is with a dyno.

i dont have much experience if any with caburated system and vacuum or centrifugal advance distributors, but MSD may make a piggy back timing controller that you could use. 35 deg btdc is a lot. here are a few pics of the ign base maps on my 8.6:1 SR20DET. max ign i was running was 14-15 deg under WOT.



 

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Discussion Starter #3
Thanks!!! I know that carbureted is different than what you guys use, but as a guide all your results will help.
 
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