The perfect amount of dwell

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BottleFed70
Experienced MS/Extra'er
Posts: 310
Joined: Fri Jun 24, 2005 3:22 pm

The perfect amount of dwell

Post by BottleFed70 »

Is there any trick for finding the perfect amount of dwell WITHOUT using an oscilliscope?

I'm just setting up my ignition now and found that at 3.0ms I was getting misses at idle. Upping the dwell to 4ms seems to have fixed that, but now I'm wondering if I shouldn't increase it more, but worry about overheating the coil etc..
1970 Ford Mustang
MSII, v3.0 PCB, v2.36 firmware, Megatune 2.25
PSIG
Super MS/Extra'er
Posts: 1146
Joined: Sat Jun 12, 2004 12:02 am
Location: Seattle, WA area

Post by PSIG »

Lance wrote this up: http://www.msefi.com/viewtopic.php?t=7281 but needs some basic info that I don't always have. In this next ignition install I'm doing (single coil V8 ), I will be setting dwell and will try the thory that not enough causes misses and too much causes the VB921's to run hot. So, I'm going to note the dwell that sparks consistently and then increase it until the VB921's start getting warm. If the spread is narrow, I'll leave it there. If the spread is wide, I'll split the difference... or something.

That's my hairbrained idea anyway. Image I'd love to hear of any other techniques!

David
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