Point gap and dwell

Reply

  #1  
Old 07-14-08, 03:59 PM
Banned. Rule And/Or Policy Violation
Thread Starter
Join Date: Oct 2007
Posts: 176
Point gap and dwell

what is the diff. between point gap and Dwell, and what if you set the gap only?
 
Sponsored Links
  #2  
Old 07-14-08, 04:28 PM
Member
Join Date: Sep 2004
Posts: 238
6 of one half dozen of another

They are two ways of expressing/controlling the same thing, the amount of camshaft rotation that the points are closed.

Set one per spec and if all is well the other will follow. Used points will be pitted, so a feeler gauge is harder to use. Set the dwell if you have a meter. A larger gap should yield a smaller dwell.
 
  #3  
Old 07-14-08, 05:55 PM
Banned. Rule And/Or Policy Violation
Thread Starter
Join Date: Oct 2007
Posts: 176
Thanks for the reply, that is what I was thinking, I am a ford man and alwys set the gap only, but my boat engines have a gap and dwell setting and I never really asked the question before.
 
  #4  
Old 07-14-08, 11:29 PM
Member
Join Date: Jul 2008
Posts: 3
The dwell is a more acurate way of setting the point gap basically. You can go either way, but just setting the gap can be hit and miss. I probably haven't set either in probably 15 years or more.
 
  #5  
Old 07-15-08, 03:55 AM
Banned. Rule And/Or Policy Violation
Thread Starter
Join Date: Oct 2007
Posts: 176
I still own a few things with points in them one of them being my 1988 Carver, I have thought about converting it to solid state but enjoy the reliability of points, I mean they can always be filed and reset in the event of failure, however when the pointless dist. fails you better have the tools and new module or you are dead in the waterand calling for a tow if you have only one engine that is, but outside of my toys I have not set points in years also.
 
  #6  
Old 07-15-08, 07:06 PM
billys68ss's Avatar
Member
Join Date: May 2003
Location: USA
Posts: 1,459
Point gap is the the distance between the contacts on the point set. Dwell is the amount if time the contacts are closed. These 2 items are adjusted totally separate. You can adjust either without affecting the other. The gap is adjusted with the points on the highest point of the cam. Depending on the design of the engine the cam will have multiple points equivalent to the number of cylinders. These cam lobes open the point contacts firing the ignition system.
The dwell is where the contacts open in relation to the spark plugs wires location on the distributor cap. This location can be changed by rotating the distributor while it is installed in the engine. This can be understood better by a BTDC (before top dead center) or ATDC (after top dead center) dwell setting. If your engine requires a setting that is not perfect 0 degrees the dwell must be adjusted. This means the ignition system does not fire when the piston is exactly at top dead center.
Hope this helps ya,
Billy
 
  #7  
Old 07-15-08, 07:27 PM
Unclediezel's Avatar
Member
Join Date: Dec 2006
Location: Northeastern PA.
Posts: 2,230
I realize its the same thing when you get to the "Nitty -Gritty" ...But what Bill has just described is Ignition Timing.
Much Kudos.....I was never able to time a motor with a dwell meter......

Did you keep the points in your Chevelles???????
 
  #8  
Old 07-16-08, 04:04 AM
billys68ss's Avatar
Member
Join Date: May 2003
Location: USA
Posts: 1,459
Well... actually they are not the same thing. They are two totally separate settings. Yes they go hand in hand, but dwell is essentially the fine tune timing of the ignition system. The point gap is just that a measurement across two contacts. If you dont have the point gap set correctly it will never fire properly. ie hot or cold fire.
Nope, threw out the old points distributors and put in new HEI units. Gutted and ground the gear off of the old points distributor and use it for priming new oil pump on fresh rebuilds. Stick a drill on it and away it goes.... oil geyser...
Billy
 

Last edited by billys68ss; 07-16-08 at 08:05 PM.
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
'