Yes, Five Star, my distributor is dual pointed, and it was timed by Dave Groh at Yesteryear Ford (he used a Sun machine). That is a very interesting contraption you included. It's probably not necessary to solve my current problem.
What about the convertability of the Crab cap as opposed to the other one? External connections should be more reliable than all those stuffed-in ignition wires going at every possible angle, but it's not evident from the photo whether the Crab style fits on top of the metal distributor body and the rotor makes contacts inside the "crab"

After I pulled the plastic parts of my distributor, I found electrical continuity to all the terminals, including the coil post in the middle. (I measured no more than 11 or so Ohms of resistance from the spark plug end to the terminals inside.)

 

If memory serves me right you have to change the complete Distributor. The Crab is much easier to change wires on.

I use them when ever i have the chance to, so far the one I have is the same as yours and works fine, but the minute it starts acting up its change up for me.

I have a crab Distributor all ready to go on. I've used them on my 37 pickup, and 39 Car. You just have to change the Timmong Cover Plate from the old 3 hole to the 2 hole.

 

5 Star,
Now that there's no easy substitution of that crab-design distributor, can you offer your experience about how intense should be the spark at the plug?
I observe a bright "lightning bolt" of a spark from the center of the coil to ground, which seems to indicate that the condenser is performing well--nice story, by the way about the shock treatment of unsuspecting mechanics.
I fastened a used spark plug (grounded with a 14 gauge wire and alligator clips) to the ignition wire boot of several different cylinders. I also inspected the rotor and gently bent up the contact, thinking it might not be making a good connection to the center pole of the distributor cap. I came, I saw, I cranked. An initial spark jumped the test-plug gap, which I had cleaned and filed beforehand, then not much spark or a faint orange blip of a spark.
What do you make of that?

 

[quote=ejmaso;12231466]
I should add that the resistor on inside of the firewall is not jumpered, so that at the input side of the coil, I read about 3.5 volts when the points are (presumably) open.
A temporary jumper across that resister did not make any difference in the starability.

 

ejmaso

What spark plugs are you using? Its possible through flooding that you might have fouled the plugs, and possibly need a new set.

If you using champions, which I quit using years ago, and switched to NGKs, I think the number is 6Bl thats (Six Bee Ell) or B6L, anyway never had an issue since.

If your getting good spark and fuel no reason it shouldn't fire, and if you have a rough idle it could be a number of issues. Vacum, fuel, spark, the list goes on.

 

Thanks again, 5 Star.
I ordered a set of plugs from Auto Zone, following a tip from a motorcycle web site. You order the NGK plug for a 1960 AMC Rebel 4.1 liter V8, 2 barrel carb, and you get the B-6L.

Fouled plugs is a real possibility in my case, considering the fuel problems I've had and not enough running time at normal temperatures.

 

Hello Five Star,
I took your advice and installed a set of NGK plugs (B-6L). My flathead started and ran roughly for about a minute before I shut her off. It didn't sound like all cylinders were firing; the vacuum gauge danced around 12" instead of holding steady at about 16" of mercury when I had this thing running more regularly last year.
I looked at the quality of the spark at each ignition wire boot, with the plug grounded. All were sparking quite brightly and regularly, which I take to mean that the condenser, the internal terminals of distributor, and contact of the primary wire from the coil--all these secondary circuits seem to be working.
A compression test and visual inspection of the virginal plugs revealed these results.
#1 90 psi light grey residue on insulator
#2 90 ; clean insulator
#3 75 ; clean insulator
#4 80 ; darker grey residue
#5 80 ; clean
#6 90 light grey residue
#7 70; dark grey residue
#8 75 ; clean

This makes me wonder if 2, 3, 5 and 8 weren't firing much at all.

Should I have run the engine longer to let it warm up?

 

ejmaso

Has that truck been sitting for awhile? Do a wet compression test, pull out all the plugs a squirt a little oil down each cyl let set for awhile turn the engine over a few times plugs out.

Take another test after this plugs out no ignition, see what you reading is after this. Reinstall plugs and let it run for awhile to get warmed up, then retest compression, with plugs out.

You may have some sticky valves or rings this should cure it if they aren't worn real bad.

I had a Merc engine that was a hell of a lot worse than yours after running ig after doing what I mentioned above I had 105 in all 8 cyls.

I don't know where you are located, what I mean in city or rural if rural add a little oil while engine running down the carb mixed with some gas. It will smoke like hell but will help lubricate rings and valves.

When you have done all this pull all the plugs and recheck compression. Let me know what it is then. Sounds like you have you ignition issue solved by what you have told me.

P.S. just in case your wondering why I said to remove plugs when taking a compression test is its easier to turn the engine.

 

Five Star,
In my testing of your helpful suggestions, I did a "wet oil" compression check and noticed the measured pressure in cylinder #1 rose from 80 to 100; others remained about the same. I also changed the oil, because the old stuff sure looked like it had been diluted with gas from all this cranking and fussing.
However, I want to ask you about the fact that the cylinders that are not firing evenly or consistently are ALTERNATELY distributed in the firing order. That is, plugs 1, 4, 6, 7 are the blackened ones after a brief and rough engine running. Given the 1-5-4-8-6-3-7-2- firing order, I wondered whether the spark might be weak after every OTHER sure firing. Could this suggest that the capacitor is not recovering enough to deliver a strong spark to the next terminal? Have you known capacitors to begin to fail and show this kind of symptom?

 

Yes if you gor the plugs wet from gas there probably not firing correctly. Aslo your compression could be due to the fact that the valves could be sticking a bit.

Run it for awhile then retest them.

 

ejmaso

Sounds like you have a good engine there judging by your compression readings.

I had one similar as far as uneven compression reading, one or 2 cylinders were down to 60 & 55. I first took off the heads and the valves were sticking a little freed them up put the haeads back on put a little oil in the cylinders, and turned it over a few times let it sit for an hour, then fired it.

Ran it for about an hour or so and all the cylinders were at 1-105 across the board. It just needed to be run free up the rings and valves, you might have a piece of carbon stuck in a few of the valves it will eventually blow out.

The black on the plugs is a sign of it running rich, but the others are okay so no need to adjust the carb any. Just be patient and let us know how you make out.

 

Hello Five Star,
I ran the engine for five minutes or so, but not so long that the temp rose to the middle of the gauge. She was idling rough, with 15" of vacuum and some fluctuation. Shut down and would not re-start. When this happens, is there a possible "flooding" condition? Or is this likely to be a result of some carbon piece holding back a valve, as you guessed? Seems to me that if the engine starts once, there isn't much that has changed for the brief time before the next attempted start.

 

Did you by chance punp the carb? If you did that is why it won't restart, these Flatty's are super sensitive to pumping the accelerator on a warm engine, they will flood very easy.

You have to run the engine longer than 5 min to get everything working properly, and 1/2 way up the heat scale is far from overheating.

Either try that or pull the heads off and check see if you have restriction under a valve from closing, or carbon build up which will have to be cleaned manually.

Again don't pump or choke a hot or warm Flathead engine.

 

Hello Five-Star,
A Ford guy in Terre Haute noted, based on the symptoms of which plugs were consistently mis-firing, that the manifold is divided into two channels: # 1-4-6-7 go through one of the carb barrels and 2-3-5-8 through the other. I took apart the carburetor looking for a plugged jet, without noticing a blockage directly, but I cleaned all the passages with carb cleaner aerosol.
In the process I noticed that the new power valve I had installed was leaking at its gasket, and furthermore, the fuel bowl had been empty. It is almost certain that gas had been dribbling out of the bowl and making a super rich mixture especially on the channel feeding the blackened spark plugs. I also noted that the accelerator pump wasn't squirting much of anything, and I'll order a new pump piston or seal for the same. The hard restart now looks to be related to an emptied fuel bowl.
The engine ran much more steadily after this repair, and I've got more work to do in adjusting the idle.
One question about the oil pressure, though. I changed the oil two weeks ago, and may have overfilled it with 10W-30, at least as far as the dipstick reads, because I did not calculate how much the oil filter cannister holds. My additional 1 - 10 pound oil pressure gauge did not register more than 6 pounds on the recent restart; the regular gauge (the sender is new) did not show much pressure. Would the leaking power valve have diluted the oil with gas and lowered the oil pressure? What's your recommendation for weight of oil on Flatheads?

 

Yes thats quite possible on the power valve if ts one of the new ones then it was most likely the CHINA brand, with the garbage diaphram in it.

When the power valve goes your engine if it will run will be blowing black smoke like crazy out of the tail pipe. Then will eventually quite the engine that is. Pull out the dip stick and smell the oil on it if you smell gas then by all means change it ASAP.

There is also bad fuel pump kits going around with these bad diaphrams, and the gas we use today with the Ethanol in it doesen't help it any.

Years ago when the unleaded gas came into being we had a guy in our group who regliously with every fill up used to put a small Baby Food jar of oil in the tank, and it never smoked.

As far as the oil pressure sender goes make sure you have the right pressure one for your engine. These old Fords will run on 10 lbs without harm to them, so as long as you have some in it and its a used engine with alot of miles on it, I wouldn't worry. Also if it is as I just mentioned used with plenty of miles on it, I wouldn't use 10 W 30, thats a detergent oil and with the good stuff taken out of it makes it even more of an enemy to your engine. Look up the additives that have been removed from engine oils. Myerlf I use straight 30 weight oil, or even 40 if you can find it.