My 63 is misbehaving.

[David Thomas]

I hope someone can shed a little light on this, cause' I think it's dark up here right now.

 

My 63 runs great, idles fine, vacuum gauge is steady when using ONLY the primary side of the Carter AFB. If I crack the secondaries, it starts stumbling shaking missing, will not rev any more and will occasionally backfire, of course vacuum goes virtually to 0 when the secondaries are opened but bounces right back. I can rev it all day on the primaries and it will run without missing a beat, pulls strong. It will cruise at 60 - 80 mph as long as it is on the primary butterflies. As soon as I crack the secondaries it will start to stutter. I can rev it in neutral and get the same results, so it does not have to be under a load to misbehave. Vacuum stays steady when holding a high idle.

 

Here is what I've done so far, by steps.

 

1. Check timing, balance carburetor. Noticed dwell would vary from 33° at idle down to about 28° with increased rpm.

2. Rebuild carburetor, found nothing wrong. I really thought the secondary circuit was plugged up because I very seldom open them.

3. New rotor, Dist. Cap. Old were sort of iffy

4. Check plug wires with Ohm meter, looked normal

5. Check voltage to coil and Pertronix trigger, cleaned all connectors. Voltage was good, 14 + volts to coil and ignition module.

6. New spark plugs and wires, old looked ok.

7. New fuel pump, blew compressed air through line back to tank.

8. Checked Flame Thrower coil, 1.8 ohms across terminals, 8K ohms from terminal to tower.

 

 

Unless the ignition module is breaking down or the coil is weak, I'm at a loss. I would think, if the coil or electronic trigger were failing it would run poorly on the primary circuit of the carburetor, also. I'm stumped at the moment. The variation of the dwell is not out of line but may be an indicator the module is suspect. I would think, it should hold steady.

 

Thanks.

[Kurt]

True, you don't have to stomp it but it sure is fun : ) I remember the 1st time I heard this fantastic sound I was in the back seat of this very car as a little kid as my grandfather was intercepting my mom driving her car up ahead when she made a wrong turn. Just another reason I love this car.

http://6364cadillac.ning.com/video/kurt63-dwnshft-mp4-3

P. S. Sorry about the fire drill with adding this comment & video. Still learning this site

[David Thomas]

Jason, I agree on the coil. Probably could have just replaced that and kept on trucking, but, I wanted to upgrade to the Ignitor II so I bit the bullet and did the whole shebang.

Tony, you're right. The smooth power these cars put out is deceiving. You don't have to stomp on it to make it down shift to go, just feed throttle slowly and you'll accelerate briskly without all the roaring fanfare. I rarely get into my car enough to make it down shift to accelerate. Just smoothly give it more until you are above the shift down speed and then open it up to really go!

[Jason Edge]

Congratulations on getting the Caddy running right! I'm thinking maybe coil was main culprit !

[David Thomas]

Jason, Tony, JK and others that have followed this thread.

This morning, I pulled the distributor out or my 63 and installed the PerTronix II and Flame Thrower II coil. I decided it would be easier to R&R things with the distributor out on the bench. I also wanted to get the rotor pointing in the correct position for #1, like the book shows. The mechanic that rebuilt the engine some 60+ thousand miles back put it in 180° out.

After finishing up I cranked it up, and let it warm up, then set the timing. First impression was, it was running better. I took it for a 20 mile run to give it a test, it ran smoother and better than it has in a long time. The new coil and ignitor fixed the problem, it ran out full throttle pulling smoothly all the way. I think the coil was the real culprit, causing all the headaches.

In trying to figure this out, I have given my old girl a Major Tune Up. Carb rebuild, ignition, coil, plugs, wires, distributor cap, rotor, fuel pump and fuel filter. She should perform well for a long time!

I appreciate all the suggestions everyone offered.

Thanks,

David

[David Thomas]

Tony, I agree with the after market or alteration from stock, causing most problems. I was real tempted to convert back to points. The PerTronix III had more features than I though a street car should need plus added complication that might fail early. Again, going back to the dependability of aftermarket parts issue, I decided the simpler PerTronix II would be less complicated than the III and an upgrade from the PerTronix I that I have. The coil and Ignitor have been in my car since 2004, I don't recall ever leaving the key on but that does not mean that someone else that worked on it didn't. The module did not have the tell tail sign of a housing affected by heat that PerTronix said it would have, if the ignition was left on. I suspect the Ignitor is ok and only the coil is weak. To step up to the Ignitor II I had to buy the coil also and should reap the benefits of being able to leave the ignition on and have another 5K volts coil voltage over the standard Ignitor set up.

Thanks for your thoughts,

David

 

[David Thomas]

Hi Tony,

You and JK may be correct that this is a carburetion issue, although, inspections have not supported that. And, it's not that I couldn't overlook something. Carburetion issues, that was my first choice for the cause and I removed the carburetor to inspect it and the parts under it.

After finding inconsistency in the coil tests, I'm now leaning more towards the coil breaking down or producing a weak spark. I decided to upgrade the ignition to the PerTronix II and Flame Thrower II coil. When they arrive, I'll know soon enough after installing them, if I have a fix.

I'll definitely post the cure, once I stumble onto it.

Thanks,

David

[Jason Edge]

It definitely sounds like the coil may be suspect and something you can switch out quickly and rather inexpensively.  I didn't have to remove the distributor or anything when I installed the III. I went from a II to a III but basically you are just removing the points and condenser (if original) and replacing with their module. I remember on the II there was a spacer plate you have to set within a tolerance (not hard to do) but did not have to do this with the III. The III really was a simple bolt on.

[David Thomas]

Good Morning Jason, Tony, Jk,

Last night I did the tests Pertronix suggested. The coil showed some variation and may be my suspect. The cold Ohm reading would fluctuate between 1.2 & 1.5 ohms. The voltage test was good. I started the engine and let it warm up while checking for fuel leaks. Just prior, I had worked on a fuel leak at one of the filter fittings that was reluctant to seal after disturbing the fuel lines for the carb rebuild. After finishing the fuel check I shut down the engine and re-checked the coil Ohm reading to find the resistance had dropped to .5 ohms after heating up. ?? That indicated, according to Pertronix that I needed a resistor in the ignition circuit, so, I removed the 12v line and connected the factory resistor. The car wouldn't start, it would hit while cranking but die as soon as I released the key. Re-connected the 12v line and it started right up. I think Jason may be on to something with his throw some money at it, and I may order an upgrade ignition module and coil. It's not like I haven't already thrown some money at it. ;o) Jason, question, you just installed the ignitor III, did you have to disassemble the distributor to install the module? I understand it senses off the point cam lobes, do you have to put some kind of adapter over the point cam? The capabilities of the III may be overkill for my use, the II would probably be the better choice for me.

Jk, your thoughts on the vacuum leak are viable but the vacuum gauge reading does not indicate vacuum issues. I tend to agree on the "only on the secondary circuit" problem, that is what is really confusing me. I do have another carburetor that I think is ok, and may resort to trying that. This may end up being carburetion or vacuum issues, but I haven't found any obvious problems with what is there so far. The running issue began before I rebuilt the carburetor. The symptoms, misbehaving only on the secondary's, is why I pulled the carburetor first to inspect it. I really thought I had secondary fuel metering circuit restriction but did not find one. I have thought about a cracked manifold or other such vacuum issue. The reason I discount a vacuum issue, is from my vacuum gauge readings. They are normal to this car, the vacuum readings I see are the same as they have been for years. I did inspect the insulator for cracks and the manifold carburetor mounting area. All looked good there, I did not pull the manifold to inspect the bottom. My understanding of vacuum gauge reading, If there were vacuum leaks, it would perform poorly on the primaries also, balancing the idle mixture would be difficult and the vacuum gauge reading would be lower than normal.

I appreciate all the input you guys have on this. Obviously, "I'm stumped". The two things I have seen in my inspections, that do stand out, are the dwell fluctuations with rpm and the coil ohm readings. I'm thinking if the coil is giving a weak spark, although sufficient to fire fuel delivery from the primary circuit but not sufficient to fire the extra flood of fuel when the secondary circuit is dumped in, too, thus blowing out the fire. Not just one cylinder is missing, it seems all of them are, causing the engine to shudder on it's mounts.

Thanks guys,
David

[Jason Edge]

David,

It's easy enough to just say throw money at it, but there are some definite advantages to the Pertronics II over the I, and the III over the II. If it is in your budget it might be a good idea to consider stepping up to a III. Even if you don't solve the full throttle problem you should have an improved ignition setup.  The Carb swap as Tony mentioned is also the other obvious choose. Good luck and yes definitely tell us what the problem ended up being.  Since WOT and the secondaries wide open is sort of related to rpm, (but not completely) I'm wondering if the secondaries wide open is just a coincidental mechanical condition and the problem might be actually an ignition that is breaking down under higher rpm.  Either way, I'm just speculating at this point considering all the other information you have posted..

[David Thomas]

Tony,

If someone with the pertronix 1 and matching flame thrower coil installed could hook up a dwell meter to see if their unit changes dwell with RPM, that would maybe shed light, if my unit is acting normal in that respect. I have considered going back to points and trying another carburetor. I have another AFB that fits a 66 A/C car and should work ok, it was used about 1K miles after being rebuilt but has been sitting for several years.

First chance I get, I'll do the Pertronix tests by the step, then proceed from there.

Thanks,

David