Distributor/Electrical Issue

[6lucky13]

Recently my car (Avatar…1936 with ’37 engine) started to miss under load…first and second gears. I planned to change the condenser (FA49) but drove the car in a local 4th of July parade. There were no issues at the slow parade speed and car did not overheat...max temp about 200F. After cooling down for about 2 hours, went on the trip home and, after about 2 miles, the car stumbled badly and had no power. Towed home.
The terminal caps showed damage at 2, 4, 7, and 8 electrodes (see photos). Based on the firing order, I suspect a problem with one set of points (?). Distributor looks fine to me but I don’t know what I should be looking for! The rebuilt distributor had about 2250 miles on it as did the Skip’s rebuilt coil and FA 49 condenser.
The only changes I made to the car previously were to replace a failed cutout with a Fun Project cutout (about 400 miles ago) and replace a failed Optima battery with a lead acid one (about 150 miles ago).
Any ideas about what’s going on here?
Thanks…Kerry

[Mart]

I can't say what the problem is, but it can't be caused by one set of points. Both points are used equally for all cylinders. (the exception to this is the Lucas distributor with 4 lobes). The cylinders listed are not in any particular order either in the firing order. 1,5,4,8,6,3,7,2. It is interesting that they are paired together, though. It isn't a carb jetting thing where the middle two cylinders on one side and the outer two on the other have a problem. (Had this with a blocked jet)

Yes, I'm a bit stumped, I would be interested to see what other people can come up with.

Edit: Could the timing be over advanced? If the caps are located like I think they are, the spark is scouring the cap material but only on the sides that are closest. There is no scouring on the other 4 because the cap material is further away.

I suspect you do not have a problem on those 4 cylinders, but a general problem that has damaged those 4 terminals because of the way they are arranged in the caps.

Mart.

[supereal]

When a vehicle stumbles under load, but evens out when cool, it is often due to insufficient fuel to meet demand. My '47 used to do than once in a while, so I just turn on the electric fuel pump. and the problem disappears. A partially restricted fuel line will do it, as will lack of a properly vented fuel tank cap.

[Terry,OH]

The cork gaskets go on the other side of the distributor caps. With the gaskets on as shown in your photo you are increasing the distance between the rotor and the cap terminals. In addition the caps will not seat correctly. There are no gaskets between the inner caps and the distributor. The gaskets should be between the outer and inner cap only.

[BUBBAS IGNITION]

I think you have two problems, one is the wrong placement of the gaskets like Terry stated. The other is loose , mis fitting wire ends on those cylinders. Its actually hard to get a proper wire end that "snaps" into the caps....

[JM 35 Sedan]

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6Lucky13, it would be helpful to know which distributor you actually have on your '36 with '37 engine. Based on the inner cap pictures, it's an early helmet distributor, but which one? Early '36, late '36, or '37 to '41? The part number on the inner cap suggest late '36 or '37-'41, but then I've seen those 68-xxxxx inner caps sometimes mistakenly used on '32 to early '36 distributors. Some pictures of your distributor posted here might help.

[34fordy]

Originally Posted by Terry,OH

The cork gaskets go on the other side of the distributor caps. With the gaskets on as shown in your photo you are increasing the distance between the rotor and the cap terminals. In addition the caps will not seat correctly. There are no gaskets between the inner caps and the distributor. The gaskets should be between the outer and inner cap only.

I believe Terry has the answer here--I notice that the "hot spots" on both caps are opposite side to the caps notches--Makes me wonder if the caps are seating only part way and cocked into the dizzy and the gap greatly increased on one side--I wonder how hard it is to fasten the wire retainers when the gaskets keep the inner caps from seating--Could also be wrong caps for the housing as John said--

[BUBBAS IGNITION]

I had posted once regarding how hard it is to get a good seat with the wire ends.
Brillman and Buru makes the correct end with the latch bump. ( berus are hard to get ) i use brillman. Note the bump or ledge to snap into the machined grove on the cap sides........

https://brillman.com/product/old-sty...coil-terminal/

[6lucky13]

Looking at the terminal caps again...I see that I do have a problem with incorrect placement of the gaskets and with seating of the caps on the distributor as suggested by Terry,OH and 34Fordy. It was difficult fastening the wire retainers. I need to redo the caps and orientation which are not seating correctly.

Attached are pics of the distributor. Are the 68-12116 caps correct for this set up?

Thanks

Kerry

[Mart]

You might find you need to file the diameter of the caps slightly to fit snugly into the distributor body. I'm not sure, but I think they tend to grow a bit with age. Check there is no corrosion in the hole, though, that can also cause a tight fit.

I suppose you could fit each cap in place in turn and observe the rotor to tip clearance from the opposite side.

Mart.

[Kahuna]

6lucky13
One last thing to check would be the inner caps themselves.
I had a terrible time with my engine due to cracks in the caps. (very difficult to see)
Engine would cut out badly at any speed above 2900 rpm.
Bubba sold me NOS caps & the problem went away.
JME
Jim

[Terry,OH]

68-12116 is the correct inner cap for your 37-41 distributor.

[6lucky13]

An Update...I installed a back up distributor with a new condenser (FA49) which i believe was responsible for the bad stumble and no power I was having. I re-used the Skip built coil and the terminal caps which had good continuity from the electrode to the end of the spark plug wire (thanks to Jim for the tip on the Brillman ends for a future change). I fixed the incorrect placement of the gaskets (good catch Terry, OH). The electrode to rotor gap was about 0.006. What is the effect of this increased gap on performance? Car runs very well!

[Mart]

Great - glad you were able to get to the bottom of it.

Mart.

[Terry,OH]

The coil will output high voltage to a limited value. In normal operation the coil will output voltage much less than it's full capability. Increasing the gaps the spark has to jump will increase the coils output until it can not output past it's limits. The high voltage at the plugs decreases and there may be no spark. Ford Spec. for the rotor gap is .0065 to .0125

[6lucky13]

Thanks for the specification on the rotor gap. I searched but could not find it. So I’m within that range.
My question came up when I purchased new DC terminal caps and the PI said to set rotor gap to 0.003 – 0.005 (attached file). So I was concerned that mine was 0.006 with the used caps.
However, I found an older thread by 39topless where he raised the same question (Setting helmet rotor/cap gap). https://www.fordbarn.com/forum/showt...g+helmet+rotor After reading that thread, I guess anything less than 0.025 (spark plug gap) is OK but the smaller the better.

[6lucky13]

Part 2…A few weeks ago I posted about a miss and rough running in my ’37 engine (see above). I apparently solved the issue using another rebuilt distributor I had and a new condenser (FA49). See my post #13. The only parts I reused were the end caps, plug wires, and Skip’s rebuilt coil. The plug wires showed good continuity from spark plug end to end cap terminal.
The car ran great for about 150 miles and the miss started again. Could the coil be defective? If so, how can I test it? I’m also thinking that the under dash resistor is bad. How do I test the under dash resistor for functionality?
I would appreciate any other thoughts about trouble shooting the miss.

[ford38v8]

Kerry, First thing to check is the condenser connections, which must be clean and firmly connected. Next is to replace the condenser itself.

Your under dash resistor likely isn't a problem, but voltage to the coil from the resistor can be checked. With engine off, bump it over to close the ignition points, and check the resistor input to the coil. You should have about 3 volts, no less. If the points are open, it will read full battery voltage minus the resistance of the ignition switch, which can be dismantled and rebuilt for improved conductance.

[JM 35 Sedan]

Kerry, it sounds like you are right back to the initial problem.

I have had, and recall others here having had experiences with the ignition resistor nichrome wire having high resistance crimp connections, and/or intermittent connections, which can cause a problem like you are experiencing. In some cases it's possible to repair the connections with high temp solder, or silver solder, but if you have a known good spare resistor, try that.

A new capacitor/condenser can also go south pretty quickly, so give that another check/test.

Also, as Alan mentioned, check the internals of the ignition switch to make sure the contacts are clean and making good connections.

[Tinker]

Under dash resistor can be checked with a volt meter easily, but you need to see if it's doing it under load or while driving or hot. Some cheap alligator clips and some 8 awg wire works well to create links to the driver seat.