dwell adjustment - Team Camaro Tech
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post #1 of 17 (permalink) Old Nov 22nd, 05, 08:27 AM Thread Starter
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dwell adjustment

I'm a newbie when it comes to ignition stuff so I was talking with a friend of mine who is going to help me breath life into a motor that hasn't been started in 4 years.
I've got all the bolt on parts covered that I'll need, and I bought a new cap, rotor, coil & points as I figure they will be needed (the inspection cover is missing on the existing dist. cap)
In our conversation, he asked if I had a dwell meter. Not wanting to red flag my lack of engine knowledge, I just said "no", but I wanted to ask "WTH is a dwell meter?" but I didn't.
So, what's a dwell meter and how is it used?

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post #2 of 17 (permalink) Old Nov 22nd, 05, 08:47 AM
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Re: dwell adjustment

It reads the point gap in degrees and they generally have other functions such as voltage readings. Basic equipment needed for tuning older point type ignition. Other tools needed are a vacuum gage and timing light. All of the functions by these tools can be done by "ear' and other means, but it is best to have them. Probably $125 total at Sears for all of these tools.

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post #3 of 17 (permalink) Old Nov 22nd, 05, 10:01 AM
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Thumbs up Re: dwell adjustment

Like 'Gary' says, a Dwell Meter reads the time the Points are Closed in Degrees of Distributor Rotation.

If you set the point gap at @0.018" at the peak of the distributor lobe then the Dwell will come in @30deg - if everything is good in the distributor.
You can also 'eye-ball' the gap just to open a bit on the lobe - start the engine - turn the 1/8" "Allen" adjusting screw in (clockwise) until the engine picks up a missfire condition - then turn the screw out 1/2 turn and the dwell will be close enough to work until you can set it exactly with a meter.

I'll bet 'PDQ' is jumping up and down right now yellin' - 'I KNOW - I KNOW'

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post #4 of 17 (permalink) Old Nov 22nd, 05, 12:13 PM
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Cool Re: dwell adjustment

Chunk the points in the trash, JMO! Install an electronic ignition. But if you really want to keep them, set them with the dwell meter at 29 degrees. They will rev better at this setting.

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post #5 of 17 (permalink) Old Nov 22nd, 05, 01:19 PM Thread Starter
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Re: dwell adjustment

Quote:
Originally Posted by Motorhead62
Chunk the points in the trash, JMO! Install an electronic ignition....
Ahh yes, updating is my plan. I've already have an electronic ignition ready to go, but I wanted to put it all original first to get the feel of how this car felt and ran "back in the day".
Then as I modify it, I will have a greater appreciation for the adjustments.

...and some people say you can't re-live history. Bah!

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post #6 of 17 (permalink) Old Nov 22nd, 05, 04:23 PM
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Re: dwell adjustment

Points have many disadvantages:

1) They "float" at high RPM, thus killing your power

2) The points corrode rather quickly

3) The cam lobe contact wears down and the setting changes. The gap actually gets smaller, which increases the dwell, subsequently retarding the timing (ie: power loss).

Go electronic, save yourself the aggravation...........

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post #7 of 17 (permalink) Old Nov 22nd, 05, 06:19 PM
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Re: dwell adjustment

I've had my dwell meter for 35+ years - they don't make 'em like this any more (solid chrome die-cast housing, glass lens, etc.); considered a relic these days, but an essential tune-up tool. If your distributor is set up properly with good bushings, breaker plate, and spec mainshaft end play and you buy GOOD points (28-32 oz. tension, not production 19-23 oz.) from Accel or Blue Streak or Borg-Warner HP, the Delco distributor will work reliably to 7000+ without a miss - all of mine do, always have.




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post #8 of 17 (permalink) Old Nov 22nd, 05, 06:25 PM
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Cool Re: dwell adjustment

Quote:
Originally Posted by JohnZ
I've had my dwell meter for 35+ years -

Wow - so my Hansen Hawk meter is over 10 years older than your's - how time flys

Now I'm really feeling old...
John

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post #9 of 17 (permalink) Old Nov 23rd, 05, 05:56 AM
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Re: dwell adjustment

Points have advantages:
1. Easy to troubleshoot if "no spark" symptom is recognized.
2. Easy to exchange with one tool.
3. Easy to prevent from corroding if the correct capacitance is selected and better materials, thank you technology. This prevents contact material from transferring from one contact to the other.
4. Easy to achieve higher rpm, change to a stronger spring set, as JohnZ suggested.
5. Peace of mind given after exchanging points and problem goes away.

6. And finally, cheaper in replacement cost than a module.

And yes, I still have my Heathkit Ignition Analyzer (oscilliscope) from 1972.

Also, having a spare points ignition system around is an excellent troubleshooting tool when one suspects an ignition problem.

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post #10 of 17 (permalink) Old Nov 23rd, 05, 03:16 PM
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Re: dwell adjustment

Quote:
Originally Posted by Everett#2390
Points have advantages:
1. Easy to troubleshoot if "no spark" symptom is recognized.
2. ..........................
LOL, you probably always see the glass as "half full". Hey, it's great to be an optimist, but I think if points had any real advantages at all, they'd still be in use today. The only "point" I might concede to you is #1, although an OBD code reader can sometimes be easier.

Me, I still have my MAC Tools dwell/tach meter from 1970, but it sure doesn't look anywhere near as nice as JohnZ's............


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post #11 of 17 (permalink) Old Nov 23rd, 05, 09:28 PM
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Re: dwell adjustment

Quote:
Originally Posted by Chevy-SS
LOL, you probably always see the glass as "half full". The only "point" I might concede to you is #1, although an OBD code reader can sometimes be easier.
Actually, the glass is too big, in either case, half full or half empty.

The time it takes to plug in the OBD code reader, the point set can be changed out. When one understands the Kettering ignition system and the effects of atmospheric pressure has on a vacuum when working on a carburetor, its simple.

I'd be the first one to turn to EFI if I had the tools and parts to change and could always download a working program to get back to Square 1. Technology has come a long way with the internal combustion engine. Why just today, I read Chrysler has made 425 HP/425 ft./lbs. of torque from a 6.1L V8. The same goal achieved from the 60's 426 Street Hemi, more power per cubic inch. As soon as electronic control of valves is perfected, who knows what's ahead.

You're glass is empty, let me get you your next cold drink.

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post #12 of 17 (permalink) Old Nov 23rd, 05, 11:46 PM
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Re: dwell adjustment

The dwell meter measures the opening of the points in your distributor. The (+) on the meter is connected to the coil (-) and the meter's (-) is connected to ground. The meter should be adjusted to 30 degrees using an allen wrench through the "window" of your distributor. Once you have adjusted the dwell to 30 degrees, you can set the engine's timing, but the dwell must be adjusted first.

As others have pointed out, the points wear and the gap changes, so adjusting the dwell would be the first place to start when timing your engine. a major improvement would be a "Pointless" ingition.

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post #13 of 17 (permalink) Old Nov 24th, 05, 07:13 AM
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Re: dwell adjustment

Quote:
Originally Posted by Everett#2390
........
You're glass is empty, let me get you your next cold drink.
I'd like a bottle of very cold St. Pauli Girl dark beer please, with no glass.

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post #14 of 17 (permalink) Old Nov 24th, 05, 01:35 PM
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Wink Re: dwell adjustment

Quote:
Originally Posted by braber427
The dwell meter measures the opening of the points in your distributor...
Wrong -
It measure the 'Closing' of the points in degrees of rotation ...

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post #15 of 17 (permalink) Old Nov 24th, 05, 01:59 PM
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Re: dwell adjustment

Seems to me that the degrees of dwell is the angle measured between opening and closing (amount in degress the points are open) or the angle between closed and opening (amount in degrees the points are closed). Not sure which.

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