47 ran rough then not at all. Need ideas.
 

On a two hour cruise Saturday engine started skipping a beat hear and there. Was kind of annoying then got worse over the weekend so I thought I'd try to fix it. Here's what I've done so far. What have I missed?

1. Monitored spark coming out of coil while driving. Although not smooth, misses in spark didn't seem to correspond to engine misses.

2. Replaced the condenser with new one that tested within specs (since that's the easiest fix). Didn't help.

3. Checked for voltage at battery side of coil. That was good.

4. Checked all of the sparkplugs and cleaned them. Checked spark in each wire to each plug. Most were smooth and consistent. Some were irratic but did not seem to correspond to engine misses.

5. Removed the distributor and dismantled, cleaned and lubed and checked all shaft/bearing clearances for any wear. All were good. Replaced the rotor and points, double checking their gap. Checked for their proper operation at distributor side of coil with test light. Light went on and off appropriately indicating points were opening and closing. Didn't help

6. Tried different timing settings. Didn't help.

7. Bypassed the resistor in case it was the problem. Didn't help.

[Seemed the more I did the worse it got.]

8. Tested the coil that seemed OK but tried two other coils just in case. Didn't help.

[By this time the engine would hardley start and if it did would only run for a short time before dying.]

9. Checked for adequate fuel flow and pressure to carburetor. Accelerator pump was not pumping so replaced my Stromberg carburetor with a Holley 94, whose accelerator pump worked perfect, in case the carburetor was at fault. Didn't help.

So, here's where I'm at now: If I plug a spare spark plug wire into the bottom of the coil and hold it near a head stud nut I get consistent bright spark. But, if I plug in the wire to the distributor and put my timing light on it to monitor spark I get very sporadic spark, then steady once in a while enough to idle for a few seconds, then nothing and the engine dies.

What else can I do or check before removing the entire spark plug wire harness and replacing all of them? That is the hardest thing to do and my last resort only if you can't think of anything else.

Any ideas?:confused:

Re: 47 ran rough then not at all. Need ideas.
 

Hows the cap and rotor?? What point setting was there?? ken ct.

Re: 47 ran rough then not at all. Need ideas.
 

We had problems with our 47 that we converted from 6v to 12V.
Ran good, than not at all.
We had a bad resistor.
Good luck,
Bob

Re: 47 ran rough then not at all. Need ideas.
 

Points were set at spec: 0.014 to 0.016 in.

Re: 47 ran rough then not at all. Need ideas.
 

I've bypassed the resistor just to get a stronger spark for diagnosing. It's still good.

Re: 47 ran rough then not at all. Need ideas.
 

Someone with real expertise will jump in here soon. The steady coil spark when disconnected from the distributor and then intermittent when connected to the distributor confuses me. If the distributor is functioning correctly it should charge the coil the same no matter what the coil wire is connected to. Also, you didn't mention bypassing the ignition switch with a jumper from the battery to the coil. My guess is that you have a breakdown in the feed to the coil or a bad distributor.

Re: 47 ran rough then not at all. Need ideas.
 

I'll go with bad dist or dist cap might need a good cleaning

Re: 47 ran rough then not at all. Need ideas.
 

From what you've said, I suspect a bad high tension lead between the coil and distributor. also, carefully check distributor cap and rotor as suggested by KenCt. Good luck.

Re: 47 ran rough then not at all. Need ideas.
 

I would try a another condensor after checking the OHMs to see if it's on the money. Hopefully Bubba will chime in here to point us the right direction.

Re: 47 ran rough then not at all. Need ideas.
 

Bypassing the ignition switch, as mentioned above, would be something to try. Contacts in the switch could be a high resistance connection that heats up and becomes a worse connection as it gets hotter. This also applies to other connections in the ignition circuit. A stranded wire with most or possibly all the strands broken, but still touching making contact, will eventually get hot enough to cause an open circuit. Sometimes a terminal poorly crimped to a wire will cause a high resistance connection that gets worse with heat.
A coil with shorted or burned open windings may seemingly check okay with an ohmmeter but fail to work properly as the windings heat up. Sometimes while trouble shooting problems like this we inadvertently replace defective components with other components that are also defective.

I had a similar situation with my '35 fordor last month and the problem turned out to be a poor/intermittent solder connection of the grounding strap to the back of the condenser. Repaired that and completely went through the distributor, cleaning, oiling and resetting everything. It has been running great for the last 200 miles.

Re: 47 ran rough then not at all. Need ideas.
 

Henry,
Try replacing the coil. An intermittent coil will drive you nuts while trying to isolate the problem.

Re: 47 ran rough then not at all. Need ideas.
 

Sorry. I double posted.

Re: 47 ran rough then not at all. Need ideas.
 

I agree that this is a good source to suspect. I had the identical problem Old Henry tells of, and (after much parts changing and hair pulling), it turned out to be a bad primary voltage connection between the coil and distributor.

Re: 47 ran rough then not at all. Need ideas.
 

If the secondary high tension wire from the bottom of the coil is not attached to anything that will complete a circuit on the other end buried down deep in that crazy two layer distributor cap, no spark would go through it for the timing light pickup to detect. One more indication that it's probably in that distributor cap from heII - a nightmare to deal with - gotta remove the fan, generator, and the entire sparkplug wire harness. Hate it. Don't wanna do it. Just wanna drive it. But, looks like that's the next step.:(

Re: 47 ran rough then not at all. Need ideas.
 

I would convert it to a crab cap and rotor much easier to work on and only 1 cheaper cap to deal with, ken ct.

Re: 47 ran rough then not at all. Need ideas.
 

Ken has a good point. Change what you are calling the distributor cap from hell, that's a nightmare to deal with, to a crab cap setup, but making sure you have a good gasket seal between the cap and the casting, and good sealing rubber boots where the spark plug wires enter the cap. Should be much easier to work on as compared to your existing double cap system.

Re: 47 ran rough then not at all. Need ideas.
 

Henry i have the cap,rotor,clips,nipples and corect gasket if you want to change it. All USA made parts. ken ct. 1-203-260-5945 or PM me.

Re: 47 ran rough then not at all. Need ideas.
 

I appreciate the suggestion of a crab cap. I am, indeed, sorely tempted but am probably too committed to authenticity to change to that. This will be the first time that I've had to work on the cap and wires since I put them in 5 years and 35,000 miles ago so I'll probably keep it authentic. Will probably replace all wires and both caps while I've got the whole mess out of the car.

Re: 47 ran rough then not at all. Need ideas.
 

The first thing I'd do is a compression check, you may have stripped the fiber gera??

Re: 47 ran rough then not at all. Need ideas.
 

OldHenry, check coil to distributor wire, the one that runs from the condensor side, if you haven't already maybe a break or shorting out?

Re: 47 ran rough then not at all. Need ideas.
 

I have experienced a bad cap. It deteriorates and then gets so bad it just won't work. Same with a rotor. You seem to have covered everything else, I'd recommend the crab for ease of access. My personal experience is to use the lowest resistance leads and plug caps, it reduces the ht load on the cap and rotor.

Mart.

Re: 47 ran rough then not at all. Need ideas.
 

I know this probably wont help, but a wise old flathead mechanic once told me "90 percent of flathead ignition problems, are fuel related"
Did you by any chance just get a fresh tank of bad fuel somwhere along your route?

Re: 47 ran rough then not at all. Need ideas.
 

I just did an experiment to test my theoretical answer above to see if it was correct. Fortunately it was. (Whew. Glad of that. Hate to be wrong. :o) I put the timing light pickup on the spare sparkplug wire coming out of the coil then cranked the engine. When the end of the spark plug wire was not close enough to a head stud nut to spark, the timing light did not flash. Whenever the end of the sparkplug wire was close enough to spark, the timing light flashed too. Always nice to have a "calculated guess" verified as accurate. Again, more evidence that there's a break in the circuit somewhere in the high tension line from the coil to the distributor cap or in the cap itself.

Re: 47 ran rough then not at all. Need ideas.
 

[QUOTE=JM 35 Sedan;526734]Bypassing the ignition switch, as mentioned above, would be something to try. QUOTE]

Thanks for the suggestion. Tried that. Didn't help any.:(

Re: 47 ran rough then not at all. Need ideas.
 

Thanks for the suggestion. Bypassed that wire with a jumper wire. Didn't help. :(

Re: 47 ran rough then not at all. Need ideas.
 

Thanks for the suggestion. Bought a new coil that tested good (with Ohm meter) and installed it. Didn't help. :(

Re: 47 ran rough then not at all. Need ideas.
 

Thanks for the suggestion. Tried a different condenser that read within specs on the multimeter. Didn't help. :(

Re: 47 ran rough then not at all. Need ideas.
 

I'm not sure how to test for bad fuel. Just filled up at a Texaco which is a Top Tier station so I hope it wasn't bad gas. How would I know?

Re: 47 ran rough then not at all. Need ideas.
 

Just did compression check. Here are the results in psi.

#4-82 #8-65
#3-79 #7-80
#2-91 #6-89
#1-84 #5-84

My engine was rebuilt 25,000 miles ago and this compression test is at 5,000 feet elevation which lowers the sea level specs of 105-125 psi to 70-90 psi.

I'm not seeing any problem here that would keep the engine from starting nor effect its running smoothly. Do you? :confused:

Re: 47 ran rough then not at all. Need ideas.
 

Old Henry have you tried a new set of plugs? Had a similar problem to you. Went through everything. Put in 8 new ones and all was good..

GB

Re: 47 ran rough then not at all. Need ideas.
 

Thanks for the suggestion. Although my plugs were new 9,000 miles ago, at your suggestion I just tested each one by removing it, plugging it into the end of the spare wire I have coming out of the bottom of the coil, and cranked the engine with the plug laying on a head bolt. Every one fired consistently and reliable so it does not appear that they are my problem. :(

But thanks for your suggestion.

Re: 47 ran rough then not at all. Need ideas.
 

All the plugs spark when connected directly to the coil. The coil is working, the plugs are working.

More evidence that the cap is at fault, or at least must be the next area of investigation.

Keep going it will become clear soon enough.

Remove the cap and leads and examine it very closely, there may be a crack allowing the spark to leak to ground or just get lost in the ether.

Mart.

Re: 47 ran rough then not at all. Need ideas.
 

a plug can break down under compression. replace them and see if thats a contributer. less expensive start before tearing the distributer apart first
... don

Re: 47 ran rough then not at all. Need ideas.
 

Are you useing the dist cap with the rabbitt ears or the crab cap. I've had 2 of the black crab caps that have a carbon trace from the terminal close to the 2 snap clips and the spark would go right through the cap to the snap clip. Walt

Re: 47 ran rough then not at all. Need ideas.
 

Take the dist out and lay on fender run a ground wire to dist case.
Add longer wire from points to coil,longer power wire to coil.
The coil wire out put to near ground should spark 1/2"
Turn key on and turn dist by hand and watch it spark.
If good and sharp turn check for loose shaft if ok
Must be caps and rotor.

Re: 47 ran rough then not at all. Need ideas.
 

It would seem that you have checked everything short of the plug wires. If you get a steady spark out of the coil, but not when you run through the caps and the wire looms, that woudl be a good place to check. If you are using the orignal wire loom tubes, it is possible that you are cross firing through bad wires inside the tube. Try running a seperate set of wires that are new and outside the tubes.

Re: 47 ran rough then not at all. Need ideas.
 

I'm using the stock double distributor cap. That's all there is left to check. I've left it 'til last since that's the hardest thing to check. I've got to remove the fan, generator, and entire spark plug wire loom to check it but I'm at that point now. I will order a new cap and wires and when they come I'll replace them and hopefully have the problem solved.

THANKS TO ALL FOR YOUR KIND CONSIDERATION OF MY PROBLEM AND ALL OF YOUR HELPFUL SUGGESTIONS. I APPRECIATE IT VERY MUCH.

Re: 47 ran rough then not at all. Need ideas.
 

OK. I peeled the ruddy octopus off of the top of my engine. Here's the inside of my distributor cap.

http://i1059.photobucket.com/albums/...psd6bc2e7a.jpg

http://i1059.photobucket.com/albums/...psdc3d4974.jpg

http://i1059.photobucket.com/albums/...a/IMG_3732.jpg

Even with my untrained eye I think those big gouges in many of the posts can't be good. For sure the cap has got to be replaced. (It only has 30,000 miles on it. :eek: Why not?)

Question is: The only way I can think those gouges got in there is for the rotor to hit them. Why did it hit them? Is there something wrong with my distributor that it would allow the rotor to hit those posts and wear those big gouges in them? If so, how do I diagnose the problem and how do I fix it?:confused:

ADDENDUM: I think I found the answer. I took the distributor out and found play in the shaft that the rotor is mounted on. Worn shaft or bushing I'm thinking.

What's next? New distributor? Keep in mind I'm not a machinist that can remove and reinstall that bushing if that's what it takes.

AND LATER: I see where I can buy both of the bushings for both ends of the distributor shaft (they're both worn). Is that all that I need to replace? Is that something I can do without machinist's equipment? If so, how do I get the old bushings out? I expect that if I can get the old ones out that I can press the new ones in.

Re: 47 ran rough then not at all. Need ideas.
 

i think you can get most of the parts you need from the catalog guys....C&G looks to have the bushings...maybe more parts if needed....Mike

Re: 47 ran rough then not at all. Need ideas.
 

Henry, it sounds/looks like you have found the main source of the problem.

A couple thoughts....

1. If the bushings are worn, make sure the shaft journals that ride in those bushings are not damaged.

2. You should be able to press or pull those old bushings out and press new bushings in place. However, after those new bushings are in place, they may need their ID's reamed to give proper clearance for shaft journals. I know this is what I had to do when I put new bushings in a '35 helmet distributor.