Are you checking the gap between the points or the gap at the (what they're calling the rubbing block) the gap where the it rides against the dist. In the manual it says to set the rubbing block gap to 0.012 in.
Points gap verse dwell
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Okay, I'm confused. The only place I have ever checked points is between the two contacts with the distributor lobe holding them open.
Don't feel bad me neither till I started working on my uncles LC. In the book it says (and has a picture) to set the gap between the rubbing block (the part that rides against the dist.) and the dist. in middle between the lobes to .012 it doesn't even show or mention point gap.
I just checked the three FSM's I have. Two of them are for F engines, both list point gap and dwell. The third one is for 2F and I find what you are saying. There is a specification for "air gap" for USA, and for the "rubbing block" for "others." So I am going to check the "rubbing block" specification and see what effect that has on dwell and I will report back. How weird is this!?! Like you said, it is measured to the flat of the distributor shaft, not the lobe and has NOTHING to do with the points. Well, not directly between the contacts as clearly the rubbing block is what will open the points. Thanks.
No, not from the file itself. I was thinking in terms of sandpaper, like silicon carbide, or similar, that is made from metallic particles. That is why I was recommending garnet, since it is not a metal base and therefore is not considered to be electrically conductive. If using a sandpaper type of product, the grit can become dislodged from the backing and be left "floating" on the surface of what you are abrading. These particles have the potential of becoming stuck to the surface of what you are sanding. Hence the recommendation for a non-metallic sandpaper, and cleaning the surface when finished with resurfacing the points.
I had never thought about using a file. A very fine file may be a viable item to use as long as you are aware of the potential of leaving chatter marks on the surface of the points. I personally feel that most people (me included, I'm a cabinetmaker) won't have the experience to know how to keep from leaving occasional chatter marks on metal when using a file.
Don
The file leaves a nice polished face, very fine.
Now, a curious thing I discovered this morning. I have another known good distributor in the shop and so it was easy to mess with. I found that the points in this distributor could be adjusted to a maximum of .012. That was by loosening the screws and holding the plate hard up against the screw and then tightening and measuring. The rubbing block gap at that setting was .006! So out came a pattern file, round, to file the slot in the points plate so I could adjust more. With the rubbing block (which is not parallel to the distributor shaft on two sets of points checked, the second new out of the box) set to .012 the points checked .019. The specification for the rubbing block is .008-.016 for a 2F. The "air gap" measurement is for a hall effect sensor, clearly not a points picture in the FSM (1979 model). I won't get a chance today most likely but I will attempt to check the unit in the car, soon, to see what the two measurements are and what is my maximum travel and then once the rubbing block gap is set, points checked, I will fire it up and see what my dwell is.
Now, a curious thing I discovered this morning. I have another known good distributor in the shop and so it was easy to mess with. I found that the points in this distributor could be adjusted to a maximum of .012. That was by loosening the screws and holding the plate hard up against the screw and then tightening and measuring. The rubbing block gap at that setting was .006! So out came a pattern file, round, to file the slot in the points plate so I could adjust more. With the rubbing block (which is not parallel to the distributor shaft on two sets of points checked, the second new out of the box) set to .012 the points checked .019. The specification for the rubbing block is .008-.016 for a 2F. The "air gap" measurement is for a hall effect sensor, clearly not a points picture in the FSM (1979 model). I won't get a chance today most likely but I will attempt to check the unit in the car, soon, to see what the two measurements are and what is my maximum travel and then once the rubbing block gap is set, points checked, I will fire it up and see what my dwell is.
New points cost under $10. I wouldn't spend a minute filing them.
I was surprised to buy two new sets of points a couple of weeks ago for less than $5.00 for both sets. Made in Japan.
You might try buying different brands and see what you find.
I would tend to agree with this, but there occasionally are times when you don't have a choice.
Don
Ok, I can imagine an "emergency" where you neglected to put a spare part in your glove box, that would leave you dead in the water if it failed and cost under $10. I guess we agree.
A very handy tool to carry if you are going to continue running points ignition is a real points file - I own several old Kohler engines and having the correct file to touch up the points is worth sourcing one since the points cover is not completely sealed to the elements .
Points and Burnishing Files – Tool Time
NEW! NICHOLSON Tungsten Point File Chisel Tip 5-1/4" 02375N
Sarge
Points and Burnishing Files – Tool Time
NEW! NICHOLSON Tungsten Point File Chisel Tip 5-1/4" 02375N
Sarge
I note that Toyotapartsoverstock.com is $10 for points. I cannot "presume" they are Nippondenso as their website catalog does not list ignition points at all. I don't know if Pinhead is monitoring this or not, but on another Mud thread, dating to 2007, he refers to the rpm range of F/2F motors as not being adversely affected by dwell and to just set the points at .018 and set the timing and ignore the dwell angle. However, in checking the FSM, there is no point gap spec, only the rubbing block gap. I am sort of anxious for all this family visiting to be over with so I can get out of taxi driver mode and fiddle with the ignition. Mind you, the rig is running like a top, but I know I have an old set of points in it.
Okay, I had a chance to work on the points/timing/dwell this morning. I installed a new set of points as the old ones I had installed a couple of weeks ago do indeed look bad. Worked fine, but we'll see what this new installation/adjustment does.
Specification for the 2F motor is;
Rubbing block gap = .012
Dwell = 41*
Timing is 7* BTDC @ 950 rpm
Idle Speed = 650 rpm
Point Gap = None specified, uses Rubbing Block measurement
So I am deferring to Pinhead's experience and did the following;
Points Gap set at .018 (the old F motor spec is .016-.020)
Timing set at the dot just visible at the lower edge of the window at 950 rpm (the timing was advanced, I had not moved the distributor from the previous dwell setting of 41*, .008 points gap)
Reduced idle speed to 650 rpm
Checked the dwell to be 30*.
The rubbing block gap checked .010.
If I were to open the rubbing block gap to the specified .012 I would suspect the points gap will reduce to about .015-.016. The increase in rubbing block gap reduces the amount of "lift" the distributor lobe will apply to the block as it has been moved away from the lobe. We'll see how this runs out and I will comment back. I'm really curious as to what impact the reduced dwell angle has on overall performance, starting, etc.
Specification for the 2F motor is;
Rubbing block gap = .012
Dwell = 41*
Timing is 7* BTDC @ 950 rpm
Idle Speed = 650 rpm
Point Gap = None specified, uses Rubbing Block measurement
So I am deferring to Pinhead's experience and did the following;
Points Gap set at .018 (the old F motor spec is .016-.020)
Timing set at the dot just visible at the lower edge of the window at 950 rpm (the timing was advanced, I had not moved the distributor from the previous dwell setting of 41*, .008 points gap)
Reduced idle speed to 650 rpm
Checked the dwell to be 30*.
The rubbing block gap checked .010.
If I were to open the rubbing block gap to the specified .012 I would suspect the points gap will reduce to about .015-.016. The increase in rubbing block gap reduces the amount of "lift" the distributor lobe will apply to the block as it has been moved away from the lobe. We'll see how this runs out and I will comment back. I'm really curious as to what impact the reduced dwell angle has on overall performance, starting, etc.
The dwell (and point gap) determines how long (in rotational degrees) the points remain closed allowing the coil to charge up sufficiently to make a spark. What really matters is the time in milliseconds that they remain closed, which depends on the RPM. My experience with street racing with points style ignitions is that you don't run into problems with coil saturation until above 6000 RPM, so you could be way off in the dwell and still run just fine at 3000 RPM.
Thanks Pinhead. I took a run up into the mountains today after the adjustment. While it started and idled beautifully and seemed smooth away from stops and coming up to speed there were a couple of passing situations where I felt like (for lack of a better term) it wouldn't come up on the pipe. So back at home I re-adjusted as follows;
Point gap = .016
Timing set to dot just at the lower edge of the window at 650 rpm.
The rubbing block then checked .015
The dwell checked a tick over 35* (2* increments on the meter)
I haven't hit the highway with it, that will happen tomorrow. However, coming back with the wife from the bus stop I was able to run it up through second into third and it pulled smooth and strong. Then a pretty good climb, on pavement, and it seemed much better than earlier.
Point gap = .016
Timing set to dot just at the lower edge of the window at 650 rpm.
The rubbing block then checked .015
The dwell checked a tick over 35* (2* increments on the meter)
I haven't hit the highway with it, that will happen tomorrow. However, coming back with the wife from the bus stop I was able to run it up through second into third and it pulled smooth and strong. Then a pretty good climb, on pavement, and it seemed much better than earlier.
A lot of guys I the thread were talking about the pertronix ignition... The factory dwell on the pertronix is something like 23*
I have used on many cars the Allison Ignition (optical) ... They were bought out be crane cams several years ago
The factory dwell on the Allison/Crane setup is 25*
I have been running the Allison for almost 23 years ... A few years ago I changed the dwell to 34*
I had '0' change in anything... Runs the same
I was thinking of going further and increase the dwell ... But... Didn't feel the need
I have used on many cars the Allison Ignition (optical) ... They were bought out be crane cams several years ago
The factory dwell on the Allison/Crane setup is 25*
I have been running the Allison for almost 23 years ... A few years ago I changed the dwell to 34*
I had '0' change in anything... Runs the same
I was thinking of going further and increase the dwell ... But... Didn't feel the need
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I had it up on the highway twice today, running strong and steady on the highway. I can't imagine that a couple of thousandths change on the points could make the difference so I will have to presume it was the change in the timing from 950 rpm to 650 rpm. If I understand the observations made here the larger point gap (.016 vs .008) will make the points last longer and the slightly reduced dwell won't be a big deal on this tractor motor. Just my $.02, but that is my experience with this discussion. Thanks to all.
Johnny C: How did you change the dwell on the electronic unit?
Johnny C: How did you change the dwell on the electronic unit?