No dwell with electronics.
Dwell Angle on Breakerless Ignition
Thread Starter
Intermediate
Joined: Sep 2000
Posts: 43
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From: Honolulu Hawaii
Dwell Angle on Breakerless Ignition
I recently installed a breakerless ignition kit (from Lectric Limited) in stock distributor. Kit uses magnetic (vice optical) pick-up, with a series of shutters that pass through the magnetic field. Car seems to run fine...
However...dwell angle reads (steady and constant) 40 degrees. Is this a problem???
Bill
However...dwell angle reads (steady and constant) 40 degrees. Is this a problem???
Bill
Tech Contributor
Joined: Jun 2004
Posts: 20,864
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Wrong twice!!! Dwell is the time or angle that the coil is charging. It is independent of whether you have points or an electronic switch. You are reading it correctly. The dwell meter doesn't know or care what is controlling the coil primary current.
Just another Corvette guy
Joined: Feb 1999
Posts: 8,518
Likes: 3,865
From: Palm Springs, CA.
Technically, you're correct.
Maybe this will help....http://blogs.orlandosentinel.com/fea...08/were_1.html
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Thread Starter
Intermediate
Joined: Sep 2000
Posts: 43
Likes: 3
From: Honolulu Hawaii
So...given that (if I recall correctly) dwell angle is supposed to be set to 32*, does the 40* which is "fixed" in the breakerless system, cause any problems to overall operations?
Le Mans Master
Joined: Dec 2006
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Longer"On" time is less"Off/cooling" time.
Tech Contributor
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Regarding the number 32, it's merely a compromise due to the limitations of mechanical switching. It's too much dwell at idle (hence the need for the ballast resistor), not enough dwell at high speed, but enough for modest cruising speeds. You could potentially run 40 degrees dwell with points if you like, but you risk the points burning quicker as the points don't open very far or quickly (the condenser does a nice job of protecting the points, but not a perfect job), and after a little rubbing block wear you could potentially end up with non-opening points, for all intents and purposes.
Le Mans Master
Joined: Dec 2006
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Big2Bird's comments are on the money.
Regarding the number 32, it's merely a compromise due to the limitations of mechanical switching. It's too much dwell at idle (hence the need for the ballast resistor), not enough dwell at high speed, but enough for modest cruising speeds. You could potentially run 40 degrees dwell with points if you like, but you risk the points burning quicker as the points don't open very far or quickly (the condenser does a nice job of protecting the points, but not a perfect job), and after a little rubbing block wear you could potentially end up with non-opening points, for all intents and purposes.
Regarding the number 32, it's merely a compromise due to the limitations of mechanical switching. It's too much dwell at idle (hence the need for the ballast resistor), not enough dwell at high speed, but enough for modest cruising speeds. You could potentially run 40 degrees dwell with points if you like, but you risk the points burning quicker as the points don't open very far or quickly (the condenser does a nice job of protecting the points, but not a perfect job), and after a little rubbing block wear you could potentially end up with non-opening points, for all intents and purposes.
Tech Contributor
Joined: Jun 2004
Posts: 20,864
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Not sure what you're asking, but I'll mention an item or two. Unlike many, if not all, aftermarket electronic ignition modules, the HEI module has a variable dwell circuit built into it. At low speeds the dwell angle may be 15-20 degrees, whatever it takes to get about five and a half amps moving through the primary circuit. This RPM (and voltage) variable dwell angle (compared to the fixed 32 degrees found in points systems) eliminates the need for a ballast resistor. As the RPM increases, the dwell angle increases, maintaining the target five and a half amp charge current. At high engine speeds, the dwell will max out at about 40 degrees, allowing maximum time to charge the coil, but also allowing a reasonable time to discharge the coil energy into the plug gap. The HEI module compensates for RPM and voltage in charging the coil, unlike points, where the coil energy drops as RPM increases, or when the battery voltage drops. It's a nice, very rugged piece of hardware.
