Setting points

[Ed Fleming]

I have 48 ply with a 1952 fargo flathead 6 my promblem is I dont know the gap setting for the points any help would be greatly appreciated thank you

[TodFitch]

Don't know for that specific engine, but all the other Chrysler L-6 engines I recall specifications for have a breaker point gap of 0.020 inches. Lacking any specific information for the distributor on that vehicle, I'd try that.

[greg g]

Unless you have a vehicle with easy access tot he driver's side of the engine, it is best to remove the distributor from the engine when servicing the replaceable tune up parts,

Mark the dist in relation to the block, then remove the cap and mark the rotor position on the body of the dist. Then remove the coil to dist wire and the crew holding the clamp. Then just pull the dist from the engine.

If you have a bench vise, clamp the dist lightly then yu can remove the points and inspect them. If they were mis adjusted they may be pitted or worn unevenly. So they may need a touch up with a points file. ALso inspect the wire that runs from the coil wire terminal to the points. This wire can be frayed or have broken strands under the insulation. If flexes everytime the breaker plate moves, and it will have only a given number of flex cycles. With the new pieces installed, you can lube the cam with some of the greas that commes with the points, give the dist shaft a spin or to to distribut the lube, then rotate it so that the points rubbing block is on a cam high point. Now you can insert your feeler gauge and set the points properly and tighte the screw down nice and snug. The gap is merely a function of # ofcylinders divided into 360 degrees, 360/6= 20. 360/8=16.

Now replace the rotor position it to point at the reference mark you made, and reinstall the dist aligining it to the mark you may on the block.

You will then button things back up. You will need to check the timing, because the points gap will have an effect on timing.

But sdoing it on the bench or inthe vise is much easier than trying to do it in the dark while bent over the fender standing on tip toes.

[TJM70's_48]

Greg...this is great advice (not to hijack the thread, hopefully). I'm dealing with my ignition system and possible problem now...and I haven't had a car with points since an old Dodge van from the 1970s...lots to re-learn.

Thanks for the good advice.

[TodFitch]

Only one slight update on greg g's fine advice: Even if you have a vehicle with easy access to the driver side and have plenty of light, still remove it and adjust on the bench.

It is so much easier to get the gap correct. It is also possible to do additional things that are hard when installed on the engine like check the bearings for wear, check the advance weights, check that the vacuum advance holds vacuum, and just generally check the condition to spot incipient problems.

[Powerhouse]

I set mine at .017 as instructed by a veteran mopar mechanic. works great for me.

[Don Coatney]

One more bit of advice to add to what Greg said. On a long block Mopar flathead (all Caniadian, and American Chrysler, and Desoto) engines you must spin and stop the engine at or near top dead center or you cannot remove the distributor.

[55 Fargo]

One more bit of advice to add to what Greg said. On a long block Mopar flathead (all Caniadian, and American Chrysler, and Desoto) engines you must spin and stop the engine at or near top dead center or you cannot remove the distributor.

Don, this I did not know, I have removed my dizzy, and the one I shipped you, without spinning the engine to TDC, am I missing something here............Fred

[greg g]

I think the deal is that the piston nearest the dizzy driveshaft may in some positions interfere with it. Putting the engine at #1 tdc assures it will clear. Also make it easy to put back in ans static time, as the engine is already where it needs to be.

[Don Coatney]

Greg is correct in his response.

[desoto1939]

I have the 39 Desoto with the long block enegine just like the CHryslers. The Dizzy has a slot onthe end that slides into the oil pumps and is not gear driven. So in this way the dizzy could only be out 180 degrees. If the piston was getting inthe way of the dizzy shaft there would have to be an oppening in the clyinder wall.

I have removed my dizzy many times without beeing a tdc. I just mark the location on the block and the location of the rotor on the body of the dizzy. And then when I put it back in i just matchup the marks and readjust to fine tune to the mark on my timing dampener.

Ans I also use a 12v craftsmand timing light and get plenty of light to set the dizzy.

rich Hartung

desoto1939@aol.com

[Reg Evans]

The gap is merely a function of # ofcylinders divided into 360 degrees, 360/6= 20. 360/8=16.

Excellent advice until the math part.

What am I missing? I did just get back home from a 2 long island tea lunch though.

360 divied by 6 don't equal 20.......it equals 60.

[TodFitch]

Excellent advice until the math part.

What am I missing? I did just get back home from a 2 long island tea lunch though.

360 divied by 6 don't equal 20.......it equals 60.

I wondered about that when I first read it. Seems like it would depend on the shape of the cam the points ride on. And it would seem that the dwell angle would be more likely to be a direct relationship than the gap in thousandths of an inch.

[greg g]

never was good at math, plus I believe it was the dwell I was thinking of. Or maybe not thinking at all. Sorry, but I believe that the fine prints says that the opinions and advice here are products of the posters and may or maynot be representative of facts. Those following that advice are warned to do so at their own risk.

[Reg Evans]

One more bit of advice to add to what Greg said. On a long block Mopar flathead (all Caniadian, and American Chrysler, and Desoto) engines you must spin and stop the engine at or near top dead center or you cannot remove the distributor.

Hey Don,

I've had the same experience as DeSoto1939. I've taken the dist. out of my 50 Chrysler 251 many times and never had to turn it to TDC. I just mark wherever the rotor was pointing and then pulled it.

Could yours having a full flow filter be the difference ?

[Don Coatney]

Hey Don,

I've had the same experience as DeSoto1939. I've taken the dist. out of my 50 Chrysler 251 many times and never had to turn it to TDC. I just mark wherever the rotor was pointing and then pulled it.

Could yours having a full flow filter be the difference ?

On my engine (James Douglas had the same issue) my distributor shaft strikes the piston shirt and cannot be removed unless I am at or near TDC. The full flow oil filter does not come into play. Makes me wonder if the replacement pistons I used have a longer skirt than the originals.

[grey beard]

This thread is jam-packed full of good advice. I have only one thought to add to all this collective wisdom.

Dwell is the number of degrees of distributor rotation that the points are in the closed position. When you set points with a dwell meter, they are set correctly. Period. If ten of us in ten different stats, at ten different seal levels and three different time zones, all set our points to the same degrees of dwell, they will all be exactly the same.

Did you know that you can pull your distributor cap, hook up your dwell meter, and set the points with the distributor in the motor? Just crank it over and read the dwell. Then make the adjustments accordingly. Too much dwell, open up the points a little. Too little, close 'em down. Keep doing this till you get it right on the schnozzola. Then the points are REALLY adjusted.

Do the job this way, and they'll stay adjusted longer, too. This is true because when you set dwell instead of point opening space, you are taking into account any bushing wear, point misalignment or breaker plate wear. This is called tolerance stack-up. You are checking the point gap electronically, as opposed to mechanically. It will always be infinitely more accurate.

Using a dwell meter to set points is much more accurate than anybody's feeler gauge, bar none. Even your sainted uncle, who was a MoPar tech for a blue million years and used to be the service manager, too, and who can set points in his sleep, will not be as accurate as a dwell meter.

By comparison to setting points using a dwell meter, using a feeler gauge and your own "feel" is about as accurate as picking your teeth with a ground shovel. JMHO.

[Plymouthy Adams]

how about another try at math..720 degrees is one rotation for the 6 cylinders..

[DigmyP18]

Hey Grey Beard, great advice on the dwell method of setting points. I had been told this exact thing by an old engine builder at a shop where I rebuilt cylinder heads back in the mid 80's. I had forgotten all about it until just now. Funny thing is that I was just setting my points last night and the dwell never did get to where I wanted it (39 deg) didn't give it my best effort either though.

One other thought too for you 6v guys. My car is Positive ground but the PO had the coil hooked up as negative ground. The coil still worked and the car seemed to run ok but my timing light and the marks never seemed to jive with what my ear was telling me ( i mean way off, like an inch or so away). Also the dwell would show 55 degrees. I switched the wires at the coil to pos. ground and now the timing light hits where it should and the dwell dropped down to the 30's.

[fortunateson]

This thread is jam-packed full of good advice. I have only one thought to add to all this collective wisdom.

Dwell is the number of degrees of distributor rotation that the points are in the closed position. When you set points with a dwell meter, they are set correctly. Period. If ten of us in ten different stats, at ten different seal levels and three different time zones, all set our points to the same degrees of dwell, they will all be exactly the same.

Did you know that you can pull your distributor cap, hook up your dwell meter, and set the points with the distributor in the motor? Just crank it over and read the dwell. Then make the adjustments accordingly. Too much dwell, open up the points a little. Too little, close 'em down. Keep doing this till you get it right on the schnozzola. Then the points are REALLY adjusted.

 

grey beard,

 

This sounds interesting but I need to know more.  Can you explain in detail to someone like me who has never set dwell how to do it please?  I have a '42 fargo with an early Cdn Dodge engine and I can't get the bugger to start .  It used to but not very well unless I waived the cutting torch at it!  I have a rebuilt carb, I set the distributor to TDC  (as best as I could off of cyl. #6 since the timing marks oon the crank pulley must have been abducted by aliens), new points and condensor.  I have about 1/4 inch spark when grounding the plug wire, compression when I checked years ago was about 105-115 across all cylinders without having two low clinders adjacent to each other.  Battery is well ground.  I'm going to 8x check that the carb is squirting correctly today.  My only other thing to replce would be the coil but it is the type that is connected to the ignition switch through the firewall with on lead (-) going to the distributor along with the main coil wire.  This has been a royal pain in th ebutt for so many years to the point I give up and wait months before going back to more misery.  I need all the help I can get and so does my truck!!!  Thanks.

Do the job this way, and they'll stay adjusted longer, too. This is true because when you set dwell instead of point opening space, you are taking into account any bushing wear, point misalignment or breaker plate wear. This is called tolerance stack-up. You are checking the point gap electronically, as opposed to mechanically. It will always be infinitely more accurate.

Using a dwell meter to set points is much more accurate than anybody's feeler gauge, bar none. Even your sainted uncle, who was a MoPar tech for a blue million years and used to be the service manager, too, and who can set points in his sleep, will not be as accurate as a dwell meter.

By comparison to setting points using a dwell meter, using a feeler gauge and your own "feel" is about as accurate as picking your teeth with a ground shovel. JMHO.

[fortunateson]

This thread is jam-packed full of good advice. I have only one thought to add to all this collective wisdom.

Dwell is the number of degrees of distributor rotation that the points are in the closed position. When you set points with a dwell meter, they are set correctly. Period. If ten of us in ten different stats, at ten different seal levels and three different time zones, all set our points to the same degrees of dwell, they will all be exactly the same.

Did you know that you can pull your distributor cap, hook up your dwell meter, and set the points with the distributor in the motor? Just crank it over and read the dwell. Then make the adjustments accordingly. Too much dwell, open up the points a little. Too little, close 'em down. Keep doing this till you get it right on the schnozzola. Then the points are REALLY adjusted.

Do the job this way, and they'll stay adjusted longer, too. This is true because when you set dwell instead of point opening space, you are taking into account any bushing wear, point misalignment or breaker plate wear. This is called tolerance stack-up. You are checking the point gap electronically, as opposed to mechanically. It will always be infinitely more accurate.

Using a dwell meter to set points is much more accurate than anybody's feeler gauge, bar none. Even your sainted uncle, who was a MoPar tech for a blue million years and used to be the service manager, too, and who can set points in his sleep, will not be as accurate as a dwell meter.

By comparison to setting points using a dwell meter, using a feeler gauge and your own "feel" is about as accurate as picking your teeth with a ground shovel. JMHO.

 

 

grey beard,

 

This sounds interesting but I need to know more.  Can you explain in detail to someone like me who has never set dwell how to do it please?  I have a '42 fargo with an early 50's Cdn Dodge engine and I can't get the bugger to start .  It used to but not very well unless I waived the cutting torch at it!  I have a rebuilt carb, I set the distributor to TDC  (as best as I could off of cyl. #6 since the timing marks oon the crank pulley must have been abducted by aliens), new points and condensor.  I have about 1/4 inch spark when grounding the plug wire, compression when I checked years ago was about 105-115 across all cylinders without having two low clinders adjacent to each other.  Battery is well ground.  I'm going to 8x check that the carb is squirting correctly today.  My only other thing to replce would be the coil but it is the type that is connected to the ignition switch through the firewall with on lead (-) going to the distributor along with the main coil wire.  This has been a royal pain in th ebutt for so many years to the point I give up and wait months before going back to more misery.  I need all the help I can get and so does my truck!!!  Thanks.

Edited August 16, 2014 by fortunateson

[linus6948]

This might be helpful...

 

http://www.howacarworks.com/ignition-system/checking-the-dwell-angle

[BigDaddyO]

Plymouthy,

The distributor turns at 1/2 of crankshaft rotation.

One complete cycle for all 6 cylinders is,in fact, 720 degrees.

However, in dealing with dwell and distributor rotation, we are dealing with one complete revolution.

There are 360 degrees in a circle.

There are 6 cylinders in our old flathead motors.

The distributor make one complete rotation to fire all 6 cylinders.

Dwell (or, more accurately, dwell angle) is the number of degrees during which the points are closed.

The correct dwell for a 6 cylinder engine is 40 degrees.

6 times 40 degrees equals 240 degrees.

360 degrees minus 240 degrees equals 120 degrees.

120 degrees equals the length of time, expressed in the degrees of a circle, that the points are open.

120 divided by 6 equals 20, which is the correct gap for the points in thousandths.

 

 

Corrected thanks to Plymouthy.

Edited August 18, 2014 by BigDaddyO

[Plymouthy Adams]

BigDaddyO, on 17 Aug 2014 - 7:50 PM, said:

Plymouthy,

There are 360 degrees in a circle.

There are 6 cylinders in our old flathead motors.

The distributor make one complete rotation to fire all 6 cylinders.

Dwell (or, more accurately, dwell angle) is the number of degrees during which the points are closed.

The correct dwell for a 6 cylinder engine is 40 degrees.

6 times 40 degrees equals 240 degrees.

360 degrees minus 270 degrees equals 120 degrees.

120 degrees equals the length of time, expressed in the degrees of a circle, that the points are closed.

120 divided by 6 equals 20.

20 is the correct gap for the points.

who has the bad math now....lol...I was only referring to 720 for the crank...not the distributor..the engine must go this to get your 360 for  the distributor..so the chicken or the egg thing...which come first...don't forget about  the rooster in this scenario..

[BigDaddyO]

Excuse me...typo.

240 is the correct value as stated in the line above.

Nice catch.