voltran

?????

ede

in referance to points? it measures the degrees of rotation the points stay open as the 8 sided cam (for v8) in the distributor rotates. the high part of the cam opens the points to make and break the eletric connection.

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-=ICON MOTORSPORTS=-
1st & 3rd

8Mike9

You sure about that ede? I've alway thought dwell was the amount of time the points were closed, in relation to camshaft degrees?

If I'm assuming correct, then the dwell time is the amount of chargetime for the coil, in relation to camshaft degrees.

Grim Reaper

Wow, its been a while since I've used one of those. Mine is covered in dust. I was under the impression it represented the amount of degrees (which effectively is time) the points were open.

Regardless, the amount of degrees of opening corresponds to width of opening on the points. A dwell meter is easier to use (especially with the GM window on its distributors) than physically setting your points with a set of feeler guages and far more accurate.

You just hook up the dwell meter as per the instructions, open the window and slowly turn the screw with an Allen wrench until your points are at the recommended dwell setting (usually in the 34* range on most GM engines).

Also, remember that if you adjust your timing, that you will affect the dwell setting of the points. This is because the turning of the distributor causes the dwell setting to be affected.

ede

no i'm not 100% sure and i can't find anything in my old manuals to tell me for sure.

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-=ICON MOTORSPORTS=-
1st & 3rd

Brent

iTrader: (1)

Actually it's the other way around. If you adjust dwell (the points gap), you affect the timing. If you turn the distributor to set the timing you don't affect the points gap.

8Mike9

The reason I say it is, I still run point's in my '57 and '59...I know to increase the dwell, I shorten the point gap...and vice-versa.

Guess it's time to pull out the MoToRs and blow the dust off

Vader

Voltran,

From one galactic overlord to another, a dwell meter actually measures the duty cycle of an input signal. In terms of breaker points in a Kettering ignition system, the duty cycle (ratio of the time on to the time off) a 50% duty cycle on an eight cylinder engine would equate to 22½° of distributor rotation. Since each complete 360° rotation of the distributor represents one complete engine cycle, the greatest possible angle for each of the eight divisions on the distributor cam would be 45° (45 x 8 = 360). A six cylinder engine could have up to 60° rotation, and a four cylinder would have a 90° maximum.

A typical V-8 target dwell angle is 30°, or a 66% duty cycle. This means that the coil is energized 2/3rds of the time the distributor is moving.

All of these numbers are valid on a single point distributor. Dual point distributors lengthen the angle by closing and opening at different times, in a staggered arrangement.

Since a dwell meter is actually a duty cycle meter, it can also be used to check the operation of ECM load devices like carburetor enrichment solenoids and fuel injector pulse widths. Since the indication is a measurement of the relative on-to-off times of a signal, actual time cannot be calculated, just a relative number. It can still be a useful tool as a go/no-go indicator.

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Later,
Vader
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[This message has been edited by Vader (edited November 12, 2000).]

Locry

so what's the ideal dwell for a v8? i haev a dual points distributor and i don't know what to set it at? what's safe for the coil? the dual point increases dwell time right? can't this be done with a single point?