How to know if Cap and/or Rotar are bad?

8N-MW

Member
[b:40bc644b7e]1948 Ford 8N. 6V. Front-Mount.[/b:40bc644b7e]

So I'm getting very weak spark and I've isolated the problem to somewhere in the distributor/coil area.

I filed and cleaned the points and set the gap. I'm quite inexperienced with filing/cleaning but I know the gap is right.

I verified timing was correct ([i:40bc644b7e]with that handy tool someone sells, I think on here[/i:40bc644b7e]).

I cleaned up the contacts on the cap and rotor with a sandpaper. It was dirty but not too wild - only about a year of use.

I have the original coil and a new coil I put on about a year ago. Should I be testing that next? I saw a post where Dell explained how to.

I did some continuity tests on the cap and rotor. This could get dicey as I don't know the correct terminology... There is the area that the spark plug wires plug into on the cap. I tested continuity from the outside to inside ([i:40bc644b7e]can't imagine it would break[/i:40bc644b7e]) and it's good on all 4. I tested the rotor to make sure there was continuity from the copper tip that rotates to the springy tab thing ([i:40bc644b7e]again unlikely to break[/i:40bc644b7e]) and it was good.

I put everything together besides the coil. I tested continuity from the part on the cap that touches the coil to the copper part on the rotor that spins around. There is continuity. However, if I test continuity from the part on the cap that touches the coil to the actual socket the spark plug wire goes in, nothing. Is this normal, does spark jump that distance? I suspect it is not and there should be continuity. Does it mean the copper is worn down and not contacting and that is the ([i:40bc644b7e]or one of the[/i:40bc644b7e]) problems?

Where do I go from here? I'm really thinking about doing the unthinkable and getting Electronic Ignition but there's no turning back form that! I'd still have a Cap and Rotor though, wouldn't I?
 
" I'm quite inexperienced "

I expect that's your problem & not the parts.

Look for carbon tracks in the cap, brass filings or cracks in the plastic.

Yes, there is an air gap between the blade end of the rotor and the t1ts in the cap.

All EI replaces is the points & condenser.

Assuming that the bushings & advance weights are ok (*see below), & that you have correct voltage to the coil (battery voltage with the points open and about half that with the points closed), the problem is in the distributor.

Once you get the distributor on the bench, the first thing you need to check is bushing wear. If the shaft has any sideways movement AT ALL, the bushings must be replaced. (*** see below).

The most common electrical failure (no spark, weak spark) points on the front mount are:

1. The insulator under the brass concave head screw & where the copper strip attaches. (it?s fiber & will wear out; poke & prod w/ your meter leads to make sure it still works) If you need to replace the insulator, use a .250 x 3/8 nylon square nylon anchor nut available at most big box home stores

2. The pigtail at the bottom of the coil not making contact w/ the concave head brass screw inside the distributor. (With the coil on, the pigtail must firmly contact the brass screw. No contact = no spark

3. The copper strip is broken or grounded to the plate. (look very carefully for cracks & breaks).

4. The condenser wire grounding to the plate or side of the distributor.

5. The tab on the bottom of the coil not making contact w/ the brass button on the cap. (With the cap on, the tab must firmly contact the brass button. No contact = no spark.)

6. Incorrect positioning of the spring clip on the plate causing the pigtail to ground. (the open part of the clip goes between 7 & 9 o?clock on the plate. That puts the straight part of the clip opposite of the timing screw at 3 o?clock)

7. Incorrect seating of the coil on the distributor due to a loose bail or no gasket.(the coil must not move at all; if it does, replace the gasket or bail. Or stick some cardboard under the bail).

8. Water/moisture inside the cap due to gasket failure or the absence of a gasket. (the cap AND coil have gaskets)

9. Dirty/corroded/burned/incorrectly gapped or misaligned points. I use only Wells, Blue Streak or Echlin brand points (* *see below). If you are using quality points and cannot get the gap to open to .015, chances are you need to replace the bushings.

10. Burned rotor, cracked/carbon tracked cap.

After you find the problem & re-check the point gap, do a continuity check before you put the distributor back on the tractor. Before you start, make sure your meter/light works.

With the distributor still off the tractor, follow these steps:

1. Coil off, cap off, points open. One probe on the brass screw & the other on both sides of the open points. On the side closest to the cam, you should have continuity. Not on the other side! If you do, you will also have continuity everywhere because the points are grounded.

2. Coil off, cap off, points open. One probe on the brass screw & the other anywhere on the body of the distributor. You should have no continuity! Now, rotate the tang on the distributor....as the points open & close, you have continuity (closed) and lose it when they open.

3. Put the coil on the distributor, cap off, points open. One probe on the lead on the top of the coil, the other on the cam side of the open points. You should have continuity!

4. Coil on, cap off, points open. One probe on the lead on the top of the coil, the other anywhere on the body of the distributor. You should have no continuity!

At this point, I just put the distributor, coil & cap all back on the tractor as a unit. The reason I do this is because it is real easy to get the cap or coil misaligned trying to put it back together, one piece at a time. The result is something gets broken or you get a ?no spark? problem.

It's possible to put it back on wrong & break it. Look at the slot on the end of the cam shaft. Whatever angle it happens to be, turn the distributor tang to match it. Make sure you can tell the wide side from the narrow side on both the cam & distributor! (close counts). Place the distributor on the front of the engine, gently push it in place & slowly turn the distributor body until you feel the tang slip into the slot. Rotate the distributor body until the bolt holes line up. Hand tighten the two bolts until the distributor body is flush with the timing gear cover.


* Unscrew the plate hold down screw & remove the C clip to get the plate out. Remove the shaft & weights. The weights should freely move.


* *NAPA part numbers:

? Points: FD-6769X
? Condenser: FD-71
? Rotor: FD-104
? Cap: FD-126



*** There are three ways to replace the bushings in a front distributor:

1. Buy new bushings (part numbers 9N12120 front & 18-12132 rear). Press out the old ones, press in the new ones and ream to fit. CAUTION: do not try this unless you have a press & know how to use it. If you break the base, a new one costs $130. If you bend the tower which holds the front bushing, a new plate will cost you $30.

2. Take the new bushings and distributor to your local machine shop.

3. Send the distributor out for bushing replacement if you do not have a local machine shop.
75 Tips
 
I assume you are talking about the front mount distributor as you said you used the timing jig that TOH sells. To test the coil set you VOLT METER to OHMS, and with one probe, it doesn't matter RED (+) or BLACK (-) as polarity doesn't matter here, touch the spring on one side and the screw stud terminal with the other probe. You should see a reading of 1.2 - 1.5 ? -that's OHMs. You can only static test the coil, actual function will be when it's mounted in use. Cap and rotor will wear a bit on metal contact points, with a dark color mark. Cap contacts can wear down -no way to reconstitute those parts so here's a proactive way to spend a few $$$. Points should be changed too rather than just trying to file them down. For about $35 you can get a whole new tune-up kit with plugs, points, rotor, condenser, and gaskets. To me, since the whole distributor will be off anyway, just replace the parts with new. Use a good brand of points like Echlin available at NAPA as part number CS-35. Most newer, cheaper Cheena made points are plastic junk and will fail quickly. Have a good, strong, fully charged battery too. Get it tested under load at a starter shop for free. Same advice there too -cheap brands have poor life expectancy.

[i:654c4848f0][b:654c4848f0]<font size="4">Tim *PloughNman* Daley(MI)</font>[/b:654c4848f0][/i:654c4848f0]<table width="100" border="1" cellpadding="0" cellspacing="0" bordercolor="#000000"><tr><td height="25" colspan="2" bgcolor="#CC0000">
<font color="#FFFFFF" size="3">*9N653I* & *8NI55I3*</font>​
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(quoted from post at 16:18:00 01/16/17)Assuming that the bushings &amp; advance weights are ok

[...]

*** There are three ways to replace the bushings in a front distributor:

1. Buy new bushings (part numbers 9N12120 front &amp; 18-12132 rear). Press out the old ones, press in the new ones and ream to fit. CAUTION: do not try this unless you have a press &amp; know how to use it. If you break the base, a new one costs $130. If you bend the tower which holds the front bushing, a new plate will cost you $30.

2. Take the new bushings and distributor to your local machine shop.

3. Send the distributor out for bushing replacement if you do not have a local machine shop.
[/url]

I printed your email off and will be doing some investigation!

However...

I suspect my bushings are bad. I've gone through this process several times and it seems no matter how "right" I do it, there is always some variation in spark quality and it degrades over time.

So I should not attempt bushing replacement without a legitimate shop press? Also, would it be a good idea to buy a new distributor breaker plate assembly (9N12150) for $28 beings I have a tiny bit of play in mine?

I know this is a loaded question. But if I get this all correct.... good bushing, good breaker plate, top brand points installed correctly, etc.... How long will it be before I'm cussing at this thing again?
 
Do NOT buy a new plate. They are cheap
stamped metal.

Take the plate, base and new bushings to a
shop to have it done correctly.

You'll probably need to do it again in 20 -
30 years......
75 Tips
 
Okay so I took my distributor apart. I have no idea how to tell if the weights are good or not, but they move unobstructed with a moderate amount of resistance.

As far as the bushings there is a very tiny amount of side-to-side play. If I take the breaker plate out and wiggle for play (essentially trying the bushings out separately) there's a bit more.

I just bought new Echlin points today (haven't put them in). The coil, cap, rotor, condenser and gaskets have been installed maybe 6-9 months along with the currently installed el-cheapo points.

Here's the deal. I'll have to take this to a machine shop to get the bushings out. I could monkey around with this and it would be very satisfying to get it working great myself (part of the reason I bought this tractor). However, life is very busy for the next month and a half. I don't have a press, a parts washer, etc...

I would like to just drop this distributor off (or mail it) somewhere. I'd like to have it cleaned thoroughly, have the weights checked, have the bushings replaced, etc... I'd just like it to be setup in the best way possible and professionally restored. From there, I can maintain the thing with some patience, luck and help from this board.

Does anybody know of a good place to have this done? I live in west central Minnesota. I did some internet searching and found an "Advanced Distributors" out of Shakopee. We have a local place that is very famous for starter, generator and alternator repair but I don't know if they deal in distributors.

Is there anybody on this forum that would be able to professionally restore this distributor? Or any suggestions?
 
I am in mid Mn. just north of Freeport. I have rebuilt those in the past. mail is open. I am disabled & work cheap!
 
[size=18:8e0083bd30][b:8e0083bd30]Update[/b:8e0083bd30][/size:8e0083bd30]
1948 Ford 8N Front-Mount 6V.

It started ([i:8e0083bd30]and ran great[/i:8e0083bd30])!

I put new Echlin points in and double-triple-quadruple checked the distributor using Bruce's great instructions and tips from everyone else here. I had my lower radiator hose heater running and had the battery charger on it. It took quite a few attempts but finally started with a shot of starting fluid right into the carb, 50% throttle and a bit of choke. The spark did appear strong and blue (but it was pretty bright outside).

To put into perspective. I'm in Minnesota and it was 23*F today. I am about 1,300' above sea level. I tested compression last March 22nd when it was 48*F outside and I had 90psi across the spectrum.

By comparison, the updated/corrected compression charts over at another website indicate I should need a "minimum" of 82-83psi with the "standard" being about 109-110.

So... I can get this thing started with some effort. However, I want to keep attacking the weakest part and make this a strong start. Everything electrical is new, clean, tight and bright. The exception being the starter and generator ([i:8e0083bd30]generator works fine[/i:8e0083bd30]). Battery is 3 years old at this point.

What's my next step in making this thing pop right off? I'm reluctant to go 12V as I want to keep the solid waterproof generator. Could my starter be the culprit and how would I tell? Or is it at the best it can be without doing engine work?
 
Your compression is ok.

Forget the starter for now. You can do a voltage drop test on it, but that's not your likely problem. And your generator doesn't have anything to do w/ it starting.

But the battery & cables do.

Put your battery on a charger. (see tip # 60)

You need a strong battery to:

1. Close the solenoid

2. Spin the starter

3. Engage the bendix

4. Provide voltage to the coil.

As the battery gets weaker, the first thing to fail is your spark. If the battery is almost totally dead, all you will hear is the solenoid clicking.

In addition to charging the battery, chances are you need new cables as well (tip # 41). And, don't forget to clean all the grounds, to include the mating area between the starter & the block.

The more current you use to spin the starter, the less you have for the ignition.

No matter what else you do, the battery must be fully charged. A float charger is helpful; not a trickle charger, but a float charger. (I use Battery Tenders on all my tractors) If you need to jump it, see tip # 43. No, it doesn?t need to be 12v. Plenty of N?s start just fine on 6v in below 0* temps. Your battery loses 33 percent of its power when the temperature dips below freezing, and over 50 percent of its power when the temperature falls below zero. A fully charged battery will not freeze until -76?F; however, a fully discharged battery can start to freeze at 32?F. So??keep the battery fully charged!

Things that aren?t all that important in warm weather become serious when it gets cold?like timing. A few degrees of timing either way at 60 or 70* isn?t likely to result in a ?no-start? situation. Well, it can at 10 or 20*. Check the timing!

Distributor gaskets are important on a sidemount & critical on a frontmount. As is the gasket under the coil. Just like with the battery cables?.if you can?t remember when you replaced the gaskets, do it this year.

Push the clutch in when you start the engine (tip # 29)

Oil viscosity can make a difference. If the tractor is going to be consistently operated below 20* F, switch to SAE 10w30; at 0* go to SAE 5w30.

Pull the air cleaner cup & check for ice.

This tip won?t make it start easier, but it will make it run better: turn the main jet out ? to 1 full turn for cold weather operating. Cold air is denser so you need a richer mixture.

While each N has its own starting sequence, none of them will start well by just yanking out the choke rod & holding it out for 5 or 10 seconds while the engine cranks. This is a gravity fuel system on a low compression engine; it is easily flooded by too much choke.

Try this:

Key on, gas on 2 full turns, clutch in, 3/4 throttle, press the starter button. Let it crank for at least 3 - 4 seconds before you pull the choke rod. Then, don't hold it out for more than 2 or 3 seconds.

If you find out it will not start w/o excessive choking, you have problems.

If you flood it, the plugs are fouled & it will be it next to impossible to start. Replace the plugs. You don't need to toss them; heat the tips for a few seconds w/ a propane torch to burn off the invisible spark-robbing deposits from today's additive filled gasoline........or wash them in brake cleaner.
Folks who live in places a lot colder than I do here in VA will argue about battery blankets or magnetic oil pan heaters as compared to lower radiator hose heaters or dipstick heaters. While the consensus leans toward lower radiator hose heaters, I can?t offer a personal observation; the only thing I?ve ever used to heat an engine was a 100w light bulb laid against the intake manifold. Freeze plug heaters are difficult to find for N?s because of the limited space in the water jacket. Magnetic oil pan heaters on the intake manifold will help as well.
75 Tips
 
(quoted from post at 16:44:57 01/17/17) Your compression is ok.

Forget the starter for now. You can do a voltage drop test on it, but that's not your likely problem. And your generator doesn't have anything to do w/ it starting.

But the battery &amp; cables do.
I do have brand new (9 month old) battery cables that are clean and shiny and very thick. It's the braided-type for ground and a thick one for hot.

(quoted from post at 16:44:57 01/17/17)
Put your battery on a charger. (see tip # 60)

I have a Schumacher charger/maintainer that does a few types of 12V batteries as well as 6V. It'll charge and also do "engine start" mode with 100 amps of power. Set me back $100, I would've paid double - well worth it!

(quoted from post at 16:44:57 01/17/17)
You need a strong battery to:

1. Close the solenoid

2. Spin the starter

3. Engage the bendix

4. Provide voltage to the coil.

As the battery gets weaker, the first thing to fail is your spark. If the battery is almost totally dead, all you will hear is the solenoid clicking.
I haven't gotten to that point yet. I get a bit over 6 volts at the coil (and down to half that as I start).

(quoted from post at 16:44:57 01/17/17)

In addition to charging the battery, chances are you need new cables as well (tip # 41). And, don't forget to clean all the grounds, to include the mating area between the starter &amp; the block.
Good here. I could include photos if desired.

(quoted from post at 16:44:57 01/17/17)

The more current you use to spin the starter, the less you have for the ignition.

No matter what else you do, the battery must be fully charged. A float charger is helpful; not a trickle charger, but a float charger. (I use Battery Tenders on all my tractors) If you need to jump it, see tip # 43.
Oh I've read your tips like the bible haha!

(quoted from post at 16:44:57 01/17/17)
No, it doesn?t need to be 12v. Plenty of N?s start just fine on 6v in below 0* temps. Your battery loses 33 percent of its power when the temperature dips below freezing, and over 50 percent of its power when the temperature falls below zero. A fully charged battery will not freeze until -76?F; however, a fully discharged battery can start to freeze at 32?F. So??keep the battery fully charged!

I imagine this becomes a non-issue when I go back out and hookup the charger/maintainer? It can get do -30F here most winters.

(quoted from post at 16:44:57 01/17/17)
Things that aren?t all that important in warm weather become serious when it gets cold?like timing. A few degrees of timing either way at 60 or 70* isn?t likely to result in a ?no-start? situation. Well, it can at 10 or 20*. Check the timing!
I did check that using the tool that someone here sells. As best I can tell I am good to go there.

(quoted from post at 16:44:57 01/17/17)
Distributor gaskets are important on a sidemount &amp; critical on a frontmount. As is the gasket under the coil. Just like with the battery cables?.if you can?t remember when you replaced the gaskets, do it this year.

Push the clutch in when you start the engine (tip # 29)
I clamp it down when I'm having trouble starting so I can monkey with starter fluid, walk around and test things, etc...

(quoted from post at 16:44:57 01/17/17)
Oil viscosity can make a difference. If the tractor is going to be consistently operated below 20* F, switch to SAE 10w30; at 0* go to SAE 5w30.
Not sure what I have in it at this point honestly.

(quoted from post at 16:44:57 01/17/17)

Pull the air cleaner cup &amp; check for ice.
That could very well be a problem. When I have troubles starting it I take the tube off the carb and it gets un-filtered air. It makes it easier to start, it's no problem to put it back on once it starts. Bad habit but necessary in the cold.

(quoted from post at 16:44:57 01/17/17)

This tip won?t make it start easier, but it will make it run better: turn the main jet out ? to 1 full turn for cold weather operating. Cold air is denser so you need a richer mixture.

While each N has its own starting sequence, none of them will start well by just yanking out the choke rod &amp; holding it out for 5 or 10 seconds while the engine cranks. This is a gravity fuel system on a low compression engine; it is easily flooded by too much choke.

Try this:

Key on, gas on 2 full turns, clutch in, 3/4 throttle, press the starter button. Let it crank for at least 3 - 4 seconds before you pull the choke rod. Then, don't hold it out for more than 2 or 3 seconds.
Thanks! I'm maybe a bit too quick on the choke at times.

(quoted from post at 16:44:57 01/17/17)
If you find out it will not start w/o excessive choking, you have problems.

If you flood it, the plugs are fouled &amp; it will be it next to impossible to start. Replace the plugs. You don't need to toss them; heat the tips for a few seconds w/ a propane torch to burn off the invisible spark-robbing deposits from today's additive filled gasoline........or wash them in brake cleaner.

I've learned the hard way not to get to that point, but I always have extra Autolite 437s around.

(quoted from post at 16:44:57 01/17/17)

Folks who live in places a lot colder than I do here in VA will argue about battery blankets or magnetic oil pan heaters as compared to lower radiator hose heaters or dipstick heaters. While the consensus leans toward lower radiator hose heaters, I can?t offer a personal observation; the only thing I?ve ever used to heat an engine was a 100w light bulb laid against the intake manifold. Freeze plug heaters are difficult to find for N?s because of the limited space in the water jacket. Magnetic oil pan heaters on the intake manifold will help as well.

Thanks for all the advice. The lower radiator heater helps A LOT. The other day it was -16F and the top of the engine was 80F.

Is there any good way to tell if a battery should be replaced? I can test voltage with the multimeter and see the percentage charged with my charger/maintainer.

If my starter spins most every time I press the button I should be fine there, right?
 
" That could very well be a problem."

That or clogged filter media. You can take them apart and clean or replace the media.

" Is there any good way to tell if a battery should be replaced? I can test voltage with the multimeter"

A voltage check can tell you if the battery is bad, but it will not tell you if it's good. The best tests are with a hydrometer or a load test. (tip # 49)

" The other day it was -16F "

I wouldn't start at that temp!
75 Tips
 

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