dwell and points

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robs 67plymouth

motown graffiti crusier
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i have a sun tester but it does not work is there another way to check dwell say with a fluke voltmeter if so how could i do it my engine seems to runnin pretty rough at idle 273, non stock 4 brrl , i hear one of my valve clatterin not bad though could that be a cause ? i hooked up the vacum advance straight to manifold could hear a change revedd up so vacum is workin checked points at .017 could my points be bad and still run thanks for any info

engine [640x480].JPG
 
There are some multimeters out there that have the tach and dwell functions. Otherwise, thats about the only way unless you can score a dwell meter.

As to running rough, I assume you've checked idle mixture and speed, as well as vacuum?
 
Is .017 correct. Seems I remember .012 being the setting. Regardless its still points. Any electronic ignition system would be an improvement.
 
The simple rules apply: More gap=less dwell less gap=more dwell. Dwell effects timing, timing does not effect dwell. Normally, the stock gap is .010", which gives about 32° of dwell. Dwell is the time in degrees the points are closed ad the spark is being generated. The shorter the firing time in degrees, the longer the primary windings have to soak. It means little at low rpm, but as you get higher, that little time makes a difference. So I set my point cars to 28° of dwell. I have no clue what the point gap is at that point...lol. But I can tell you single points with a stock coil can run over 5500rpm staying stable by doing that.
 
moper said:
The simple rules apply: More gap=less dwell less gap=more dwell. Dwell effects timing, timing does not effect dwell. Normally, the stock gap is .010", which gives about 32° of dwell. Dwell is the time in degrees the points are closed ad the spark is being generated. The shorter the firing time in degrees, the longer the primary windings have to soak. It means little at low rpm, but as you get higher, that little time makes a difference. So I set my point cars to 28° of dwell. I have no clue what the point gap is at that point...lol. But I can tell you single points with a stock coil can run over 5500rpm staying stable by doing that.
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I too set my points at 28*..Then it will be a while til it reaches the topend of its adjustment are (28-32*) I have an old sears dwellmeter that still works great.
 
just got the car a couple weeks ago it had the orig 2brrl and intake i had the edelbroc layin around decided to put it on. the afb carter carb is a 500 cfm
the engine had run the same way with the 2 brrl. when i disconected the vacum hose from the carb it did not change the idle and its on the side wheres theres constant vac ill have to take it out tomorrow and check it out . as far as the carb i turned in the left side screw {if facing eng} all the way in and did not do nothin . i have them about 2 1/2 out, my engine just shakes around at idle and that sun tester it just has a red and black i assume red goes to coil to dis and black ground on batt
 
Try bottoming (lightly) both idle mixture screws, and then backign them out one turn each. There is not supposed to vacuum present at idle on the vacuum advance port. If you raise the rpm by cracking the throttle, you'll feel vacuum there.
 
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