Point gap or Dwell?

[John76]

What is the preferred spec?

If I set the point gap correctly, the dwell angle is off. If the dwell is correct, the gap is off.

All new parts....distributor and points.

Thanks,

John

[ScottCLo]

How off are we talking? If you are only getting 20° dwell with 016 gap then there is something majorly wrong but if you are getting 50 or so at 016 then i wouldn't worry and set it off the dwell angle. Dwell angle is what matters. points gap is just to get you by if you don't have a dwell gauge.

[ScottCLo]

also make sure you set the dwell angle before you set the timing.

 

Edit:

In other words, when you change the dwell angle you are also changing the ignition timing.

Edited March 25, 2017 by ScottyC

[stephers]

Dwell should be 58-61 degrees, best to set it at the lower end with new points so as the rubbing block goes thru it's initial wear in, the dwell will increase. The gap and the dwell should correspond to each other quite closely, if not, check for wear in the dist, check the lobes on the dist shaft and make sure there is no side to side play in the dist.  Also make sure that your dwell meter is set to 4 cyl, most of them have the ability to do 6 cyl and 8 cyl as well .  It can be a little bit of a PITA but keep trying until you get it right as ScottyC mentioned, change the point gap or dwell and the timing changes.

[Simeon]

Do I hear screw adjustment points?

[John76]

Thank you.

I always shoot for a dwell of 59....and let the point gap be what it is.

However, when the dwell is set to 59, the gap can be anything from 012"-020". (spec is 016")

Dwell is pretty rock-solid at 900-2800rpm, so I'm not concerned about cam wear or play in the distributor.

[John76]

Simeon,

Does anyone remember the old cars with the window on the distributor to adjust the points on the fly? I would "tune" my dad's car almost daily with a dwell meter (when I was 12)....it was so fun!

[zinz]

Ummmm... let me introduce you to FAQ's Master Tinker...

 

Ed

Edited March 25, 2017 by zinz

['76mintgrün'02]

Thanks for the nod, Ed.

I almost revived that thread, because I made a second dwell adjuster this week.

Now I have the one installed in my distributor and one to play with on the Sun machine.

 

This time, I took a bunch of measurements and did some drawings of the bits and pieces.

The funny thing is, I changed the position of the adjuster screw and the first one is better.

The second one looked pretty on paper though. 

 

John, the BMW Blue Book gives instructions for setting the dwell using a meter, in which you make the adjustment while spinning the engine, using a remote starter switch.  You simply tighten down the points screw to where it holds, but can still be moved, using the screwdriver in the slot and between those two nubs on the points plate.  With the engine spinning, you can put the dwell right where you want it and then tighten it down.  

 

The on again off again, set / test / set / method drives me CRAZY, after having owned my '72 Suburban for twenty years.  It tOtally spOiled me.

 

Anyone running points without owning a dwell meter is doing it wrOng!

Feeler gauges will get you home in a pinch, but it is nOt an accurate method of setting the gap.

This is especially true with used points, where you are simply feeling the gap between the two highest points.

 

As mentioned above (and I'm sure you know), set dwell, then timing.  As the dwell changes, so does the timing.  Standard practice is to check your dwell and if it is within the acceptable range, you adjust your timing to work with that angle.  I think this is because it is easier to rotate the distributor, while running a timing light, than it is to set the points accurately/consistently.  

 

With the dwell adjuster, it is easier to put the dwell exactly where you want it.  The cool thing is that if your points have worn and you can put the dwell back where you initially set it, the proper timing comes back with it.  Know what I mean?  

 

(this is my favorite tOpic)

[HBChris]

Great tip, I never thought to remove the rotor and set dwell with starter spinning.  I have Pat's Tune Box, what a great tool.