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mailman
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Joined: March 24, 2005
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 Posted: Mon Jul 31, 2006 6:51 pm Post subject: Point gap? or Dwell angle? |
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Which spec is more important? Proper point gap, or proper dwell angle?
My tune-up specs (1200 40HP) call for .016" point gap. If I do that, the dwell angle is much too large.....about 58 or 59*. The dwell spec calls for 50* plus or minus 2*. If I set it at 50*, I have a point gap of about .020".
It seems to run very well at the 50* setting, so that's where I've left it.
Any thoughts? 
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Dazed42
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| Posted: Mon Jul 31, 2006 6:53 pm Post subject: |
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I set mine with the tach dwell since the dwell is what matters.
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nsracing
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Joined: November 16, 2003
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| Posted: Mon Jul 31, 2006 8:34 pm Post subject: Re: Point gap? or Dwell angle? |
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| mailman wrote: |
Which spec is more important? Proper point gap, or proper dwell angle?
My tune-up specs (1200 40HP) call for .016" point gap. If I do that, the dwell angle is much too large.....about 58 or 59*. The dwell spec calls for 50* plus or minus 2*. If I set it at 50*, I have a point gap of about .020".
It seems to run very well at the 50* setting, so that's where I've left it.
Any thoughts? |
What is this, trick question?
They are one and the same. The point gap will exert how long or how many degrees the points will stay on contact with each other. This is the dwell.
The dwell reading, in degrees, is the really fancy way to know your actual "gap". The larger the gap...the smaller the dwell.
This degree figure will give the longest wear on the peg and points.
Last edited by nsracing on Tue Aug 01, 2006 10:07 am; edited 1 time in total |
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Bruce
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| Posted: Mon Jul 31, 2006 8:35 pm Post subject: |
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Hands down, the Dwell is much more important.
The spec is 47º +-3º.
Then you have to set your timing after you alter your dwell. Later, when you replace the points in the future, set them to 47º, and your timing won't have changed. |
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krusher
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Location: europe
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| Posted: Tue Aug 01, 2006 12:04 am Post subject: |
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Have any of you used a timing light with dwell that can be used to set up a 6volt car?
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mailman
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| Posted: Tue Aug 01, 2006 3:50 am Post subject: |
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nsracing...
Not a trick question.... My point is, you can't have it both ways. Altering one alters the other. I can't acheive both specs at the same time, so which should take precedence?
My thought is dwell. Apparently others agree.
I thought the spec was 50* plus or minus 2*...... If indeed the spec is 47*, I'll have to open the point gap even farther!
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Glenn 
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| Posted: Tue Aug 01, 2006 4:07 am Post subject: |
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Dwell angle is not "as" critical as it is on a 8 cylinder engine since 4 cylinder engine have more time to charge the coil.
Dwell IS the spec, not point gap. The point gap is just a starting point for setting the dwell.
Do what I do and install a CDI box. with an electronic system dwell angle is not as important since the system will charge the coil faster so you can run a much smaller gap. I runs .010" with my system.
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nsracing
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Joined: November 16, 2003
Posts: 9462
Location: NOVA
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| Posted: Tue Aug 01, 2006 6:51 am Post subject: |
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| mailman wrote: |
nsracing...
Not a trick question.... My point is, you can't have it both ways. Altering one alters the other. I can't acheive both specs at the same time, so which should take precedence?
My thought is dwell. Apparently others agree.
I thought the spec was 50* plus or minus 2*...... If indeed the spec is 47*, I'll have to open the point gap even farther! |
This is like tweaking an idle screw...then you read the RPM figure on the timing light or a meter. The final result is the "dwell".
You adjust the points by hand...just as you adjust idle screw..by hand.
The feeler guage sets the width of the gap. This will vary because the "drag" is by feel. Just because you stuck a 0.016" feeler there does NOT mean it is. That is why the dwell varies.
It is a little tricky tightening the screw, isn't it?  Too much and you move the points even when the feeler is in.
Try this trick: If the dwell is too big (meaning points is too tight) ....add 0.001 - 0.002 (to the feeler 0.016") to compensate. Yes...2 feelers ( you do the math...whatever will give you the gross figure.)
Stick the 2 feelers in there, and don't hold it when you tighten the screw.
Hope this helps. |
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KTPhil
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Joined: April 06, 2006
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Location: Conejo Valley, CA
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| Posted: Tue Aug 01, 2006 8:58 am Post subject: |
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The dwell is the relevant measure, since that is what electrically affects ignition characteristics. Correct point gap will give you correct dwell ONLY if the points are new, flat, and parallel. With worn, rounded, pitted or titted, or misaligned points, the gap as measured with a feeler gauge will induce too large a dwell angle. Use a dwell meter if you have it; if you don't, make a pully mark as shown at the end of this description, and set it with a simple test lamp:
http://www.desperado.scvnet.com/~philh/images/dwell.pdf
Last edited by KTPhil on Tue Aug 01, 2006 2:03 pm; edited 1 time in total |
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67Beetle2017
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Joined: August 01, 2006
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Location: Pasadena CA
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| Posted: Tue Aug 01, 2006 1:55 pm Post subject: |
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| mailman wrote: |
nsracing...
Not a trick question.... My point is, you can't have it both ways. Altering one alters the other. I can't acheive both specs at the same time, so which should take precedence?
My thought is dwell. Apparently others agree.
I thought the spec was 50* plus or minus 2*...... If indeed the spec is 47*, I'll have to open the point gap even farther! |
You are correct in having to open the point a little further.
Just a thought. Points must meet squarely inorder to last the longest. Make sure the points are perpendicular to each other (both stationary and movable arm). Only tweak the stationary arm to square the point contact patch. Make sure to use Bosch point lube on the rubbing block also. The points will not close up so fast if you use the rubbing block lube. |
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sharkskinman
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Joined: April 26, 2006
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| Posted: Sat Jul 07, 2007 3:33 pm Post subject: |
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went back and messed with the dwell on mine
67 type 3 1641 stock
i have my gap set at .010 nad im hitting 46 about
i replaced them but didnt know (at the time)
you should put a condenser in as well
well
i got a condenser and its a bolt on one not a push in a bottom hole one
what does the condenser do exactly
and i know it "condenses"
but why
and what will a new points and an old condenser do exactly
will replace both soon prob but am not yet completely comfortable to take out the dist
is it slot (rite on or 180 off)
or is it a gear or what
but doesnt it seem strange that i have to have .010 with a stock engine???
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VW Vet
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| Posted: Sat Jul 07, 2007 6:13 pm Post subject: |
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| The condenser reduces arcing at the points when they open. It gives the electricity somewhere else to go without going to ground. |
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fubab
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| Posted: Sun Jul 08, 2007 12:36 pm Post subject: |
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One thing to be aware of . . . some meters measure dwell in "degrees," some measure in "percent." For 4 cyl engines, 50 degrees equate to 56 percent. So if your meter measures in percent (pretty common), you're shooting for 56 percent.
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Bruce
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| Posted: Sun Jul 08, 2007 11:55 pm Post subject: |
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The spec is 47º, not 50º.
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