To dwell or not to dwell

zoegrant

zoegrant

Well-known member
My 55 Ford has a 272 engine with a 6v electrical system. I changed the points and set the timing by vacuum ...I tried to check the dwell with a 12v dwell meter by hooking the dwell meter to the coil and using a 12v battery for power and a ground wire from the 12v to the cars engine. The car runs good but the dwell reads 40 degrees when the dwell should be between 26-28 degrees.
Can the car run good with the dwell being off by so much ?
Or is the dwell hookup I have giving a false reading ?
 
Lets see...you hooked a 12-volt battery to a 6-volt ignition coil ? Probably not good.
I too have a 12-volt dwell/tachometer, but never tried to use it on my '55 Ford with 6-volt electrical system. If you could completely isolate the electrical system it would read right, but you would need to have 12-volt coil, but then, not sure how to isolate the dwell-meter ground from the 6-volt car system ground.
The points, condenser, rotor and spark plugs don't care. They are exactly the same part on the '55 and '56 cars, the '55 being 6-volt, and '56 being 12-volt.
This is one of the reasons why I converted my '55 Courier to 12-volt during the build process. So I could have a modern stereo radio and be able to use a 12-volt dwell/tachometer. But the '55 sedan, being still 6-volts, just do the best I can with feeler gage for the point gap and hope for the best.
 
get an old basic dwell meter . they only have 2 leads, one goes to the dist. side of the coil and the other goes to ground. some are self powered with a 9 volt batt. some do not require a external or internal power source, and power comes from the lead that is hooked to the coil, which is what also what gives the dell reading as the coil builds and collapse its magnetic field. At least this is how I remember it. I have not used my dwell meter in at least 10 years now.
 
zoegrant said:
My 55 Ford has a 272 engine with a 6v electrical system. I changed the points and set the timing by vacuum ...I tried to check the dwell with a 12v dwell meter by hooking the dwell meter to the coil and using a 12v battery for power and a ground wire from the 12v to the cars engine. The car runs good but the dwell reads 40 degrees when the dwell should be between 26-28 degrees.
Can the car run good with the dwell being off by so much ?
Or is the dwell hookup I have giving a false reading ?
Click to expand...

On setting the timing: Why are you using a vacuum gauge?! That's a diagnostic tool for finding burned valves, blown head gaskets, and vacuum leaks. A timing light is needed to accurately set the timing. The timing can be way off from factory specs and the vacuum reading can still appear OK but performance and mileage will be down. It's quicker, simpler and more accurate to do it the right way!
 
zoegrant said:
My 55 Ford has a 272 engine with a 6v electrical system. I changed the points and set the timing by vacuum ...I tried to check the dwell with a 12v dwell meter by hooking the dwell meter to the coil and using a 12v battery for power and a ground wire from the 12v to the cars engine. The car runs good but the dwell reads 40 degrees when the dwell should be between 26-28 degrees.
Can the car run good with the dwell being off by so much ?
Or is the dwell hookup I have giving a false reading ?
Click to expand...


Dwell meters normally work on both 6 and 12V systems, at least the ones I have or have used. Those with an internal battery need no adjustments, while ones with no battery are simply calibrated for either 6 or 12V.

Now using a 12v timing light on a 6V system is connected like you did.
 
Dave...the info I used to use the vacuum gage to time the engine is off the internet including the STOVEBOLT FORUMN and a printout I had from a t-bird web site.
My 6v system works so well that I am hesitant to convert to 12v...
I am thinking about converting my point system to a Pertronix setup.
 
ALASKA JIM....I will be looking for a dwell meter that uses an internal battery..ANY ONE HAVE ONE FOR SALE ?
 
just use a feeler gauge to set them to .015"-.018" and call it a day. People used a vacuum gauge to set timing because they did not have a timing lite. use a timing lit.
 
I also just set my points with a feeler gauge. We are already at enough of a disadvantage with Y-Blocks; as I recall, my '54 shop manual recommends removing the distributor just to change out the points!! (I changed the points without taking out the distributor last year when I had all my heater motor and duct work removed and it was doable. Probably doable without removing the duct work when I was younger and more flexible.)
 
JimNNN said:
... as I recall, my '54 shop manual recommends removing the distributor just to change out the points!!
Click to expand...

The LOM DIST had to be (not exactly had to be) setup on a DIST MACHINE as point dwell and point/cam tension is critical to how the car will run. Did all line techs do it? I seriously doubt it.

Tweaking with a vacuum gauge both on ignition timing and carb balancing is a common practice. It allows full volumetric efficiency ... :confused:

... throwing those big words around again ...
 
39deluxecp...I could not get my 12v timing light to work...don't know if the bulb is burnt out or if just will not work with a 12v timing light on a 6v system.
I used a 12v battery with a ground wire running from the 12v battery to an engine ground and then connected the light to the coil as instructed on a couple of websites.
Didn't work for me but maybe the bulb is burnt out. I will test the timing light on my 12v 53 Chevy truck as soon as I can move some vehicles around to get at it.
 
JimNNN...I had to remove the distributor to install points as the distributor being set so far back on the engine kills my back and I can see better when it is on the work bench so I can be more accurate...
 
If you only have a 12 volt timing light, you can hook the positive and negative leads to a separate 12 volt battery that is not connected to the vehicle in any way, and then just put the clamp for the plug wire on # 1 spark plug wire and if your timing light and bulb are good, when you start the engine, and pull the trigger on the light it should flash. If you use just a feeler gauge to set the points , check your work by checking the gap on a couple of different lobes, as some may be worn more than others. setting points this way is pretty accurate. also set the points/dwell then set the timing. hope this helps
 
zoegrant said:
ALASKA JIM....I will be looking for a dwell meter that uses an internal battery..ANY ONE HAVE ONE FOR SALE ?
Click to expand...
I have two Sears-Roebuck dwell-meters both nearly identical from the late 1960's. They both take an oddball 4.2 volt internal battery. Some years back, I happened to be near a store that sold all types of dry-cell batteries and they had them so I bought one, brought it back home and installed it in both my dwell-meters, neither one worked. But I was not surprised. there are several small electronics capacitors inside the units that had apparently went bad over the decades. They don't last forever.
To my knowledge no one manufactures a dwell-meter that uses an internal battery nowadays, and if you run across one on e-pay, I wouldn't buy it because it must be many decades old and just about ready to crap out anyway.
 
To my knowledge, all modern dwell/tachometers are the type that work off the car battery and they are for 12-volt systems only.
My '55 Ford car seems to run best when set with a .016 feeler guage, but it can vary depending upon your car. The point gap is directly proportional to the dwell angle. If the point gap is widened, the dwell angle is decreased (which means that the points don't completely close until the dwell angle becomes zero). If the point gap is decreased, the dwell angle is increased (which means that the points are closed for a longer period of time along the flat part of the cam), thus the electrical circuit is complete for a longer time for spark to occur. The factory has pre-determined that a dwell angle of 26-28 degrees is the best setting and should prohibit the points from burning or becoming pitted.
 
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.
 
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 ?
 
Alaska Jim said:
... If you use just a feeler gauge to set the points , check your work by checking the gap on a couple of different lobes, as some may be worn more than others. setting points this way is pretty accurate. also set the points/dwell then set the timing. hope this helps
Click to expand...
Use a small amount of distributor cam grease to help keep the lobe wiper edge on the points from wearing too quickly.
zoegrant said:
... Can the car run good with the dwell being off by so much ? ...
Click to expand...
If the point gap (or dwell) isn't set correctly the ignition system won't work correctly either.
Finding a dwell meter that also works on 6v may be worth the effort. They are more accurate than a feeler gauge and a dwell reading that fluctuates by 4 degrees or more shows you the dist shaft bushings are worn out, making the point gap/dwell and timing settings unstable.
Here's a link to dwell meters for sale on ebay...
https://www.ebay.com/sch/i.html?_fr...0.Xdwell+meter.TRS0&_nkw=dwell+meter&_sacat=0
zoegrant said:
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 ?
Click to expand...
(as mentioned before) The points have to be correctly set before adjusting the timing.
Where is the timing advance set now, how many degrees advanced at idle?
The vacuum line from the carburetor should be plugged when checking or setting the initial timing.

And the rubber diaphragm inside the vacuum canister cannot be leaking or it will not function.
You'll get no timing advance beyond the initial / static setting.
You can carefully blow into it to see if it holds pressure, or not.

Does it have an original '55 Loadomatic distributor? (photos attached)
 

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