To dwell or not to dwell

[KULTULZ]

The dwell is adjusted by setting the points gap to a specified distance at maximum opening. A narrower gap gives more dwell and a wider gap gives less. Taking it to extremes, excessive dwell means that the points close too soon after opening, cutting off the magnetic field collapse before it delivers all its energy. Too little dwell gives the magnetic flux insufficient time to build up to the maximum.

Set Your Timing Last

Both conditions give a weak spark which gets even weaker as the engine RPM rises and produces misfiring at normal operating speeds. The dwell, as well as spark plug gap, do have an effect on ignition timing. The later the points open, the later the spark comes and retards the timing. The earlier the points open the sooner the spark comes and advances the timing. That is why timing is the last thing to be set in a tune-up.

SOURCE - https://www.liveabout.com/dwell-and-timing-explained-even-more-4059400

 

[54vicky]

after setting up the timing on my 55 Ford....took it for a ride and found that over 45 mph the engine starts to cut out....Should I advance or retard the timing ?

I think you have the points set wrong (too close)open them up slightly 18 thou is the number to shoot for.as to timing try 10 btc.the vacuum gauge is a good tool when used properly.I use it for carb tweaking the A/F have for over 50 years and on race car engines

 

[40 Deluxe]

40DELUXE....what is the right way on a 6v system ?

Use a dwell meter that works on a 6V. system or use a feeler gauge and then set the timing with a timing light. If needed, set a 12 V. battery on the ground next tot eh car and connect then timing light power leads to it and the pick up lead to #1 plug. If tempted to use a vacuum gauge, place the gauge in front of a tire, then drive forward about 6 inches.

 

[40 Deluxe]

after setting up the timing on my 55 Ford....took it for a ride and found that over 45 mph the engine starts to cut out....Should I advance or retard the timing ?

Neither advance it nor retard it! Find the real problem. Point gap, worn bushings, bad vacuum chamber, weak coil, harmonic balancer ring slipped, weak fuel pump, carb problems, etc. This is assuming that the timing was set with a timing light, NOT a vacuum gauge.

 

[dmsfrr]

My 55 Ford has a 272 engine with a 6v electrical system. I changed the points ...

Is the car Positive or Negative ground?
If it's wired Positive ground the Black dwell meter lead will go to the coil/distributor connection feeding the points, the Red lead to ground.

After you set the points with a feeler gauge and reinstalled the distributor, did you connect the dwell meter you have to see if it works? Red meter lead to Positive and Black meter lead to Negative.
The meter you have may work fine if connected correctly, without the extra 12v battery.

40 Deluxe mentioned 'harmonic balancer ring slipped'.
Have you checked to make sure the timing marks on the pulley are where they are supposed to be?
As the rubber layer dries out the ring with the timing marks on it gets loose and can slip out of position. There is a relatively simple procedure to check it.

The timing marks on the pulley can be redrawn if the weight ring has slipped but if it's loose it will continue to get worse and should be rebuilt or replaced before it fails.

 

[zoegrant]

dmsfrr...Yes the distributor is the Loadomatic as in your post.
I did advance the timing and it no longer bogs down at 40 mph.
I will test it again after I get a dwell meter. I will take it up on the highway to test it at speed.
Laying over the engine to get to the distributor is a killer on my back and gut.
Thanks....John
WHO IS A GOOD MAN TO REBUILD THESE ? ,FAIRLY DIRTY INSIDE

 

[zoegrant]

Are dwell meters voltage sensitive or will they work on both 6 and 12 volt cars ?

 

[Daves55Sedan]

Are dwell meters voltage sensitive or will they work on both 6 and 12 volt cars ?

Several decades ago, manufacturers produced dwell-meters with an internal battery. They do not depend upon the car electrical system at all for operation. It has it's own isolated electrical system and could be used on 6v, 12v, 24v, 48v or whatever. those units only have TWO conductors for connection to the ignition system.
In more recent years, they decided it would be immensely cheaper to produce meters that rely upon the car electrical system. Those units have FOUR conductors (two for ignition system connection and the other two to the car battery). Due to the voltage and current ratings of components inside the unit, they cannot be used with 6-volt systems. The manufactures literature specifically states "for 12-volt systems only".

 

[Daves55Sedan]

Dave, my Snap-on dwell/tach/ohm meter has a 9 volt internal Battery. it works on 6 volt and 12 volt systems. I bought it back in the mid '70's. still works fine, and is accurate. tested it this morning.

And yours would also work on 24-volt and 48-volt systems as well unless the manufacturer specifically limits which systems it can be used for in their literature.
I've got a transistor radio that was new in 1984 that still works like new, however it is mainly kept indoors in climate controlled spaces and has never been subjected to weather extremes like we have around here. bear in mind that the radio has same type capacitors (condensers) as those old dwell-meters. My units had a lot of use in the '60s and '70's then they sat in the metal carrying case in the garage, exposed to -10 degrees to +105 degrees since the 1980's. I suspect those condensers have broken down due to temperature extremes over five decades.

 

[zoegrant]

Thanks ….will post again when I get a dwell meter with an internal battery...GREAT INFO, THANKS

 

[V8 Bob]

There are two-wire dwell meters with no internal battery, like my Accurate BT-162 I've had since the '60s. You simply full-scale calibrate for the system you have, 6 or 12V pos./neg. ground. This meter is within 1 degree accuracy compared to my Sun TDT-11 which does have an internal battery.

 

[zoegrant]

V8 Bob....what do you mean by full scale calibrate ???

 

[Merc Cruzer]

See if a few pictures of Dwell meters, with no internal battery will help. I use the hand held unit on my 6 volt pos ground 53' Mercury, with the red clamp going to the ground and the black to the distributor side of the coil.

As to the Sears analyzer, I use this approach from a prior post:

https://www.fordbarn.com/forum/showthread.php?t=40659&highlight=dwell+-to


Old 06-27-2011, 04:09 PM #4

42ford
Member

Join Date: May 2010
Posts: 70
Default Re: Sears engine analyzer model 161.2161
If you just want dwell and tach. Hook it to a separate 12 volt battery

 

[V8 Bob]

V8 Bob....what do you mean by full scale calibrate ???

Well, almost full scale. The BT-162 test leads are connected to the battery and the calibration control is rotated until the meter indicates 4500 rpm when the function switch is in the dwell position. Other meters may be different.

 

[zoegrant]

V8 Bob...Just bought a BT-162 meter and will let you know how it works for me...John in CT

 

[V8 Bob]

V8 Bob...Just bought a BT-162 meter and will let you know how it works for me...John in CT

Did you get the manual with the meter?

 

[Daves55Sedan]

That old Sears engine analyzer you showed isn't much different from my modern Actron dwell/tach meter and, yes it does not have internal battery (AND is only suitable for use on 12 VOLT electrical systems) according to their literature.
He needs a meter that DOES have an internal battery, so he can use it on 6 or 12-volt cars.
That model 530 meter has only two conductors, making me think it DOES have internal battery, accessed by removing those front screws. Another thing that makes me suspect it is self-powered it that it is very old (Made in USA). Can you take the front off that handheld meter and see if there is a battery inside?

 

[Merc Cruzer]

That old Sears engine analyzer you showed isn't much different from my modern Actron dwell/tach meter and, yes it does not have internal battery (AND is only suitable for use on 12 VOLT electrical systems) according to their literature.
He needs a meter that DOES have an internal battery, so he can use it on 6 or 12-volt cars.
That model 530 meter has only two conductors, making me think it DOES have internal battery, accessed by removing those front screws. Another thing that makes me suspect it is self-powered it that it is very old (Made in USA). Can you take the front off that handheld meter and see if there is a battery inside?

Dave,

Per your request, no battery, and it works on 6 volt Pos ground (my 53' Merc) and 12 volt Neg ground (the 1970 Cougar XR-7, that belongs to my wife). I need to reset my points, they are currently set at 31, should be at 28.

 

[V8 Bob]

That old Sears engine analyzer you showed isn't much different from my modern Actron dwell/tach meter and, yes it does not have internal battery (AND is only suitable for use on 12 VOLT electrical systems) according to their literature.
He needs a meter that DOES have an internal battery, so he can use it on 6 or 12-volt cars.
That model 530 meter has only two conductors, making me think it DOES have internal battery, accessed by removing those front screws. Another thing that makes me suspect it is self-powered it that it is very old (Made in USA). Can you take the front off that handheld meter and see if there is a battery inside?

As I've already stated, my Accurate meter is two wire, no battery, and is 50 years old. And yes, I've been inside, and matches the schematic in the manual.