Trouble with a 47 Cad

[Ralph Hoyt CLC ## 20242]

I am having trouble with a 47 Cadillac V8.   I get it started and it runs for a length of time.   Take it out for a spin and not several miles from home it stops running.  Then I cant get it started again.   It sits for a day and then starts right up again.   Pulled a plug after this last time and tried to see if I was getting spark and nothing.  Pulled the cap and the points fire.  

Any sugestions would be appreciated.

[Porter]

Ralph,

How old are all the igntion components on the engine ?

How long is "runs for a length of time" ?

How far is "not several miles from home" ?

If you are confident the fuel delivery system if functioning properly then I would assume you have a defective ignition component, Bruce Reynolds had a defective coil that would work intermittently, and then even his used spare ones did the same, they all tested NG.

Sometimes you have to get ignition components tested or try a part that is known to be good, points,condensor, cap , rotor and plugs are basis tune up parts that wont break the bank depending on how old your parts are, other than that I would suspect the coil, make sure you have all good clean tight electrical connections.

Just thought Id "jump start" your post while Im killing time waiting for my NY Jets football game tonight.

I had an external coil fail on my 1990 350 Chevy distributor, I had a spark when I grounded the plug wire but it was a weak spark, sporadic running until it finally wouldnt start anymore.

Porter

[Rusty Shepherd CLC 6397]

The start when cold, stops when warmed up sounds like vapor lock which is, Im sure, what Porter was referring to when he mentioned the fuel delivery.

[Porter]

I had an old boat with a flathead six engine, it would start up and run fine when cold, after a while it would shut down and didnt want to start until sitting for a while.

The culprit was an old gas tank that would clog the fuel delivery, new gas tank , end of problem.

In my case the igntion system was okay.

Fuel or spark, choose your poison (problem). Assuming the engine has decent compression.

[Mike #19861]

 No spark? By this do you mean at the plug, wire or coil wire?  What exactly do you mean by "points firing"?

When the car will not start, and there is no spark, check to see if there is power at the positive terminal on the coil. Then check, with a test light, on the negative side of the coil with your test light and see if there is power that flashes on and off as you crank the engine.  If there is, and there is no spark from the coil, it could be a defective coil.

 From this, of coarse, I assume you still have the original positive ground 6 volt system.

  Mike

[John Washburn]

Mike,

Nope 46 and 47 were Ngative ground batteries. Prior to these years they were Postive ground.

John Washburn
CLC #1067

[Mike #19861]

 Thanks, John. I stand corrected.

  So then check the positive side of the coil for power and the negative side for interupted power while cranking.

  Mike

[John Washburn]

Ralph,

If you arer able to get a spark across the points (opening them and seeing a spark jumping across the points), but not getting a spark at the plugs is interesting.

I hope you are opening the point without shorting anything out, then you should see a spark?

Anyway, if you get spark at the points then unless you have a short somewhere in the distributor, or the coil is bad (which might be the culprit) the car should run.

Before Id go to a lot of expense pull the coil wire and clean the area in the coil where the wire plugs in. If these get corroded (which Ive seen a lot) problems will occur.

The only other problem you might check for is that the wire, 14 guage (no smaller) that goes from the coil to the distributor is ok and not shorted or that the wire is open and shorting somewhere (remember that voltage will find the least path of resistance to ground)...

Good Luck

John Washburn
CLC #1067

[Ralph Hoyt]

Thanks for all your help.   It ended up being a bad Coil.

[Porter CLC # pending]

Ralph,

Glad to hear you found the problem, we are all shadetree mechanics here (okay, maybe just me) but we get the job done.

Mike, I assume even up in Canada "coarse" pertains to the sandpaper grit and "course" would be as in "of course".

Feel free to give me a flame job at your earliest convenience or first opportunity, like every one of my posts.

LOL,

Porter

[Steve Crum 20999]

The Joisy Jets still call themselves a team? HeHe...
Bet he dont say that out loud in Mooseville!
Flamed him for you Mike!

[Porter CLC # pending]

Not too shabby, besides, Cadillac is one of their sponsors.

Cmon Steve, at least their color is John Deere green, certainly a woodchuck like you can appreciate that.

Ill settle for Eagles green this year, give a Cadillac to a player that appreciates one.

Tom Brady "not".

Pooter