Setting Points and Dwell Readings

[70 Challenger Lover]

Yesterday, I went over the new car briefly and started giving it a little tune up. In the past, I've always yanked points and upgraded to electronic. On this car, I may do that eventually but for the time being, I'll keep the points in it since the car is running nice already. I used to be good with points but I've forgotten just about everything now. I could use a little help.

As part of the tune up, I switched out the air filter, cap, rotor, wires, and plugs. All seemed to be in need of replacement so I'd like to throw in new points too. I have them on order.

After doing the tune up, I switched my gauge to dwell and it read 40. Is this possible on a well running engine? I always thought 30 was good and too far from that and it wouldn't run well if at all. As I understand it, dwell is the degrees of rotation with the points closed so high dwell means the points are not opening enough.

I'll drop in the new points tonight or tomorrow but what gap should I start with?

As far as the current points, I'll measure the gap before I remove them but what could I expect if I left the points as is? Low power?

By the way, the spark plugs were Autolite 66 which my books shows as one heat range too high for a stock 318 motor. The plugs were mostly white with a little flaky ness which makes me think lean. Could this be from too hot a plug, bad point setting, or a carb that needs a fatter main jet? The idle mixture was perfect when I checked it.

[kawahonda]

Make sure on your dwell gauge that you are using the V8 scale. Sometimes there's other scales.

40 is way too much dwell...

You will want a dwell angle of 30-34 for 340...i'd treat the 318 the same.
383/440 is 28-32

Set dwell first, then you'll have to reset your initial timing.

I don't use feeler gauge to set my points...but initially set it to .017 and then go from there with the dwell gauge.

Always better to hit the low side of the dwell range...dwell will increase over time..especially with new points until they settle. I would recommend accell performance points, and nothing else!

My challenger uses Accell Performance points....and I noticed after the first 400 miles the dwell angle increased quite a bit...it was at 38 from 32...and it ran "well"...couldn't detect any problems other than more pinging than usual, and only at WOT so I didn't notice it much.

On my 340, the mechanical advance was only 10 degrees, which is pretty darn good factory....but the vacuum advance was pushing out 18 degrees...too much. My distributor guy got rid of the factory canister and put on one that only ran 10 degrees along with a recurve. I can now run my initial at 16-18 degrees, instead of 8-10 degrees before WOT pinging.

[Chryco Psycho]

I have seen 38-40 with dual point if you can get close to that why not more dwell time is better coil saturation 

[70 Challenger Lover]

So maybe that reading of 40 is correct. I assumed I was doing something wrong and got a bad reading. So I take it that dual point set ups are designed to increase dwell time for better coil saturation? Mine is single point so does the increase in single point dwell just not open the points as far?

From what I've read on the Internet, they say the only problem with too much dwell is that at some point additional wear causes the points to not open enough to get the field to collapse so the engine dies or fails to start after that. Being a stock 318 cruiser, I'm mainly interested in reliability.

Lastly, if what I read is true, having too much dwell is like retarding the ignition timing and a v8 will see about one degree of retarding for each degree of additional dwell? Do I have that part right?

[Chryco Psycho]

 
Too much dwell & the system may quit firing
increasing dwell will delay the coil collapse & resultant spark