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Old blue was running pretty poorly so I decided to check the timing and dwell. Either my dwell meter was bad the last time I set it I ws looking at the wrong scale, because the dweell was wy off, about 45 degrees, which probably acounted for the poor acceleration from a stop. i reset the dwell as low as I could, but couldn't seem to get it below about 36 degrees, it just wouldn't set to anyrhing lower and still get spark. The points looked pretty beat up, and that might be the problem. I've ordered new points, should be in today. If that doesn't work, any suggestions? It's the 225 V-6, in a 1968 jeepster. Timing is currently at about 7 degrees BTDC. My deacceleration backfire problem went mostly away with the new dwell set, (only a little popping on hard deceleration, as opposed to the rifle shot it used to be) It's a prestolite distributer.
 

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Either you didn't calibrate the dwell meter, you are reading the wrong scale, or the dwell meter's bad.
The 225 at about 36 degrees dwell will shut down 3 cylinders, making it run downright terrible.

Set the new points with a feeler gauge, then the dwell meter should read fairly close to 30 degrees. Set it to 28 degrees.

Doesn't matter what type distributor you have either.
 

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Dwell.. ?duty cycle? measuring and integrating the voltage existing across open points (max volts) and closed points (no volts).. with a dwell meter... it would be a good thing to insure that your max voltage (battery) is within the limits you have set your charging system up to produce, IMHO
Bob
 

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Dwell is the time the points are closed, measured in distributor rotation degrees.
So yes, it's essentially duty cycle. Since it's the time when the points are closed, current is flowing through the coil during that time, building the magnetic field in the coil = energy's being stored. Then at the proper time the points open, the magnetic field collapses fast around the secondary windings - creating a high voltage = spark/boom.

Normally a 6 cylinder has a maximum of 60 degrees dwell - 360/6. But the 225 odd-fire's strange. 3 of the points opening times (when the coil fires) are closer together - those 3 only have a total time of 45 degrees - same as an 8 cylinder.

Normally a 6 cylinder dwell setting is about 45 degrees, about 2/3 of the total available dwell of 60 (an 8 cyl has a total available of 45 (360/8,) so normal 8 cyl dwell is 30, a 4 cylinder is 90 (360/4,) so 60 dewell is usual.)

But the odd fire needs to be set around 30 (2/3 of 45). Set too long the points close before the magnetic field has has a chance to release fully, starving 3 cylinders of spark.

So if you have a Delco distributor you can play with it. Set it to 30, runs nice, increase it a little to about 34 or 35 you hear a slight misfire. Much more it starts running bad, more than that it runs horrible - on 3 cylinders. Best way is to set the dwell on an odd fire around 28 - even 26 is fine.
Remember - anytime you change dwell, you are also changing timing - change dwell one degree - timing changes one degree. Lowering dwell advances the timing.

Some points wear so they close (not enough lube on the rubbing block - timing retards.
Some burn wider - wrong condenser or bad dist ground - timing advances.

Always set dwell first, then set timing.
 

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Do away with the points. Get Pertronix. I was impressed at how much better my jeepster ran after I did the conversion. I also think I started getting better gas mileage. Well worth the investment
 
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