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Discussion Starter · #1 ·
I've been tripped up on this a few times over the last 20 years (facepalm) and it happened again today. Just wondering if anyone else has too? Hopefully there is some sort of system or indicator I'm missing.

(Rough) Example:
Timing is set at 20Deg BTDC​
Timing adjustment allows + or -​
So does +5 = 25Deg BTDC?​
Or because 20 is technically a negative number does +5 = 15Deg BTDC?​

You would think this would be standardized. But it's actually not. Anyone else fought this battle before?
 

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Is this a trick question... Or just bugs you not knowing... :unsure: I'm going with it Doesn't matter which way you apply It because with the + or - the acceptable range will still be 15-25 Degrees BTDC regardless if you count the positive as closer to BTDC or farther away for BTDC

Edit; Joking response removed / My Apologies, most do not know me and brad are very good friends and I help him test his new products (Member Complaint)
 

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Discussion Starter · #3 ·
Definitely not a trick and it really bugs me not knowing. Regardless of the acceptable range I like to "pull a few degrees out" aka reduce the amount of spark advance for my nitrous maps/builds.
 

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My guess is within whatever mapping tool you are using, in order to avoid the confusion you're facing, then "pulling timing out" would be accomplished by subtracting timing. So if you wanted to go from 20 degrees BTDC you would take away, or subtract, 5 degrees to get you to 15 degrees BTDC.

Technically, as you pointed out above, you are actually subtracting timing to advance the timing from 20 degrees BTDC to 25 degrees BTDC, since you're really moving from TDC -20 degrees to TDC -25 degrees.

Since no one likes to figure out what adding or subtracting a negative number does and to make it easy you would add '+' timing to advance the timing and subtract '-' timing to pull timing out. Take timing as a net-positive number, even though it really isn't, and move it to where you want by adding or subtracting however many degrees you would like.

I'm going with it Doesn't matter which way you apply It
I'd highly disagree that it doesn't matter as adding (advancing) timing on a motor that you are going to spray can potentially end badly and you really want to pull timing out on a nitrous map.
 

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I'd highly disagree that it doesn't matter as adding (advancing) timing on a motor that you are going to spray can potentially end badly and you really want to pull timing out on a nitrous map.
The original question was in no reference to what adding or subtracting will do to engine performance or why he was even asking :rolleyes:
 

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And I'd argue that your original reply wasn't an actual answer to the original question... :rolleyes:
All members are entitled to their own opinion on posts and reply's
And all members should take all posts and replies as opinions

Nothing stops member involvement faster than when they feel in fear they can't leave their opinion by seeing members that confront other members about there post or reply
Plus they burn the OP's thread with their actions.

PM Sent
 

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Discussion Starter · #8 · (Edited)
After some back and forth with Dynojet I decided to change the terminology a bit. "Spark happen sooner vs spark happen later". I think the reason piston #2 cracked on the nitrous build was because my map was based on some incorrect advice I received (not naming names and it had nothing to do with anyone on this thread, I'm simply posting this now so if someone uses the search function in the future they can get a concrete answer).

Long story short I was using 5 when it needed to be -5. I had the spark happening 5deg sooner than stock which is actually 10deg sooner than what I was trying for.

InkedScreenshot 2021-04-27 151844_LI.jpg
 
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