For Stu Fox and Duke Williams

[Jeff C.]

I am getting 12.75v both when cranking and when ignition is on. I am getting resistance when the points are open and closed 1.5om and 7.6om. I carefully checked the ground wire and the neg coil wire and both are good. The question is how can I have 12v to the coil and no spark? I have used 2 sets of points and condensers with no change and dug out a old coil to try with no results. If it is the ignition switch why does the coil have power and the engine crank? Also the engine initially started and ran fine for 5 min. I do have a short some where of 35.4Ma but I don't see how that would cause no spark.
Any help is greatly appreciated.
Jeff

[Donald O.]

Re: For Sty Fox and Duke Williams

When you open the throttle, is there a squirt of fuel?
With the dist. cap off, are the points opening and closing when cranking?

DonO

[Duke W.]

Re: For Sty Fox and Duke Williams

Resistance between the coil negative terminal and ground with the points open should be infinite and zero when the points are closed. Your reported resistance values don't make sense, and I suspect you are measuring from the wrong location(s).

Breaker plate to ground should be zero.

The coil primary resistance ( + to -) should be about 1.5 ohm and 10,000 (coil tower receptacle to case/ground) on the secondary side. Check your service manual for actual specs of the original coil. Also the coil case to ground should be zero - make sure the coil mounting is snug and grounded - and coil + and - terminals to ground should be infinite.

Remove the ignition capacitor and check terminal to case. It should be infinite.

Also check that the RFI capacitor on the coil + terminal is not shorted.

All resistance checks must be made with the ignition OFF.

Duke

[Richard M.]

Re: For Sty Fox and Duke Williams

To add to Duke's info, it is strange that you're getting the 1.5 ohm and 7.6 ohm reading with the points both closed and open(note I reversed your order as I'm guessing the lowest reading is with them closed)

It would indicate to me that the coil- lead is still connected to the points and you're likely reading 7.6 ohms resistance through the ignition circuit back to the coil through the coil+. You say you have a 35mA short somewhere. Is that in the Main or in the IGN circuit. If IGN, something has to be fixed before moving on. If it's in the MAIN, and you have a aftermarket radio with a clock retention memory, or a quartz clock, that's your 35mA and has nothing to do with your no-start condition.

If your coil- lead was in fact disconnected from the points, and you still got those readings, you found your problem.......bad points, both sets, bad condensers, or points improperly adjusted or somehow a low grade short between the breaker plate and the point set.

You said it ran fine for 5 minutes and then it lost spark. Or maybe it's just weak spark........

I pulled my hair out a while ago over a really silly misdiagnosis. I had a 283 that was running fine, then 1/2 hour later went to move the car back in the shop. No start. I could see spark, but not realizing it was weak, in sunlight I assumed it was just the glare but I was getting good spark. Checked and cleaned the points, did a quick points test with ignition on using my test-light and meter, all appeared good. Temporarily removed the condenser. No change, no start.

Got a friend to help crank while I checked the spark at a sparkplug directly. It was there but very weak, Ahhh....gotta be the coil. Put a brand new coil on, No change.

My buddy said......"Rich, jsut put a new set of points in". I resisted and said they tested fine and I cleaned them! After another half-hour of screwin' around, I put a new set of points in.

Bang! Started right up.

The old points were intermittent and must have been breaking down and highly resistive when passing high current flow with the coil in the circuit.

Lesson learned.

[Stuart F.]

Re: For Sty Fox and Duke Williams

Saw "Fox" in the title, so I guess I should jump back in. I don't think I have much to add to what Duke and Rich have said, but I'd like to say something that might help Jeff recall what he might have done to bring this condition about. It's been many years since I've done anything with pre-63 Chevy V8's, including my first build of a 50 coupe with a 55 V8 back in 1956. That included conversion of a 6 volt car to 12 volts, etc.

Recently I installed a Pertronics II unit in a 62 Fuelie Vette that my son had sold on the conditions by the new owner, one of which was that we install an electronic conversion because he had another 62 250 hp with points that gave him much grief. To my surprise and wonderment, the Fuelie ignition circuit just used a ballast resistor as the only power source to the coil. Upon START, the 12 volts came through the resistor (not from a circuit through the starter like my 63). After startup, the ON power continued at 12 volts until the resistor heated up and gradually reduced the voltage back to about 8 volts. The 12 volt input side of the resistor was used as a source for at least 3 other contacts, and the reduced voltage side was source for 2 more contacts including the electric choke.

Now I know I'm getting old and senile, but I don't recall if this was the way my pre-63 V8's were wired. To me, that 62 Fuelie, both it's injection unit and ignition was an "abomination" that I hope Chevrolet resolved before the 63 came along.

IS it possible that Jeff is using the wrong ballast resistor and as a result he's frying his points?

Stu Fox

[Duke W.]

Re: For Sty Fox and Duke Williams

Through mid-'63 ALL Corvette 12V systems used a 0.3 ohm ballast. A running change during the '63 MY substituted a 1.8 ohm ballast and ...087 coil on 250/300 HP engines only and this carried through to '64. For '65 all engines with single point ignition used the 1.8 ohm ballast and ...202 coil.

Engines with the 0.3 ohm ballast were know to burn points, especially in cold weather. The ballast has a special "inverse resistance" wire. The colder it is, the less resistance. Burned points happened to my 340 HP SWC back in the sixties. Chevrolet wrote a TSB suggesting that the 1.8 ohm ballast be installed in cold winter months. Yeah, right! I wonder how many people did that.

In any event, the ignition circuit is a simple DC circuit (with a couple of parallel caps that don't have any effect unless the points are cycling) that should be easy to troubleshoot for anyone who has a basic understanding of DC circuits, and the service manuals have procedures and checks that should be followed.

There are cases where a simple resistance check with a multimeter (which uses low voltage) may show that a switch functions properly, but when it's loaded with full system voltage/current it doesn't work... happened on the backup light switch on another car I own. It drove me nuts until I consulted with a buddy who had a lot of experience building and testing electronics, and he said, yeah that can happen. So even though the installed switch tested "good", I bought and installed a new switch and the backup lights worked.

Duke

[Richard M.]

Re: For Sty Fox and Duke Williams

I'm still trying to figure out who Sty Fox is......

I guess some more data would be helpful too. We don't even know if Jeff is running a stock ballast or if he has a MSD or a Pertronix or something else.

But as mentioned, it could be as simple as a broken ground on the breaker plate which could be misleading. When testing with a meter, if the meter ground is on the valve cover etc, he could get his good reading, but still have a problem in the distributor. The meter ground should be on the base of the points or condenser so it's getting the same reference.

Ohming out the breaker plate to a good engine ground is always a good thing to check first. I've heard of people having a bad disributor ground(to the engine) but that seems unlikely.

Rich

[Duke W.]

Re: For Sty Fox and Duke Williams

I'm still trying to figure out who Sty Fox is......


Ohming out the breaker plate to a good engine ground is always a good thing to check first. I've heard of people having a bad disributor ground(to the engine) but that seems unlikely.

Rich

...not an uncommon problem. A couple of years ago I rebuilt a L-79 distributor that had well under 100K miles. The ground wire crimped to the breaker plate broke during disassembly. The ground wire is subject to constant flexing from action of the VAC, and the copper becomes work hardened and brittle. Strands begin to break, and it might go intermittently open for a period of time before a hard failure, which will disable the ignition system and leave you stranded, but there's a decent jury rig to get you home.

I started a thread on both the L-79 distributor rebuild and the broken breaker plate ground wire, which should be easy to find in the archives if anyone is interested because I don't start many threads.

You can buy a two-dollar ground wire repair kit that can be installed without removing the distributor.

Duke

[Richard M.]

Re: For Sty Fox and Duke Williams

Yes I probably should have worded it: ".....although rarely seen, it's possible".

BTW here are the links to your threads. I have a barrage of your docs stashed away.

https://www.forums.ncrs.org/showthread.php?97383-Ignition-failure-warning-to-all-owners&p=641768#post641768

https://www.forums.ncrs.org/showthread.php?97360-L-79-distributor-blueprint-overhaul&p=641554#post641554

Rich

[Stuart F.]

Re: For Sty Fox and Duke Williams

Jeff did indicated in his initial thread that he was undoing a "Bubba" installation of a Pertronics unit with coil and ballast resistor moved to the inner fender panel.

Hope Jeff pops in here again so we're not just talking among ourselves about his problem.

I have been called "SLY FOX" many times during my life, but I specially liked the title when expressed by the competition as they stood shaking their heads saying; "what's he got in that thing anyway?" Speaking about my Fuelie 50 Chevy coupe. My reply; "oh, it's just a Mercury flathead".

Stu Fox

[Richard M.]

Re: For Sty Fox and Duke Williams

I'm being lazy typing inside your quote...
Rich

Jeff did indicated in his initial thread that he was undoing a "Bubba" installation of a Pertronics unit with coil and ballast resistor moved to the inner fender panel.

Oh, I never saw that one...

Hope Jeff pops in here again so we're not just talking among ourselves about his problem.

Yes me too.....got me curious now. I got my money on a bad ground.

I have been called "SLY FOX" many times during my life, but I specially liked the title when expressed by the competition as they stood shaking their heads saying; "what's he got in that thing anyway?" Speaking about my Fuelie 50 Chevy coupe. My reply; "oh, it's just a Mercury flathead".

Nahhh, you shoulda' said ..."it's just a old T-Bird Y-Block".

Stu Fox

[Jeff C.]

Re: For Sty Fox and Duke Williams

OK Guys,
Do you know that the T and the Y are next to each other on the key board? I try to proof read my posts but at my age I'm lucky I can still read. Some how you all started talking among your selves while I was still in room. In any case I thank you all for your information it helps a lot. My next information will make you all think I am senile. Today I decided to replace the points with the petronix I removed. As I was cranking the engine to get the distributor to #1 firing position I saw the coil sparking to the distributor. I said what the f*** and reassembled everything and guess what the engine stated right up. I ran it for a few minutes and shut it down. Then started it back up no problem. I have been through almost all of the connections, wiring harnesses and anything else I thought would contribute to the problem during the last week but I have no idea why it started today.
Jeff

[Richard M.]

Re: For Sty Fox and Duke Williams

Jeff, Sorry about my silly joke about spelling. Sometimes things get way too serious and tense around here so I try to lighten it up a little but didn't mean to offend in any way. It was more directed too Stoo than Yoo. Sorry. I hate the fact we can't edit the Subject line when that happens. Only the Admins can do that and I don't like to send requests to them to fix things like that as they have enough to do around here.

So......Glad you're engine started. I missed your discussion about getting the Pertronix out. There's a mixed bag of opinions about those little critters. Personally I think you did the right thing. With the Perts, if you break down on the road hundreds of miles from home, you better have a known good spare in the trunk toolbox! I keep points, cap, rotor, wires, condensers, coil, VR, etc in my '59 trunk toolbox. Saved my butt a few times. Even saved my buddy's butt once when his VR went bad on a road trip.

Thoughts.... Maybe you DID have a bad distributor ground after all, and wiggling it around got it solid again. If the distributor clamp was a little loose that could happen. But as Duke mentioned it'd be a good idea to check that breaker plate ground wire too. When the Pertronix was in there that ground wire is not necessary so when you converted back it may fault. It's working now so you can rest better and move on to more fun stuff.

Rich

[Don H.]

Re: For Sty Fox and Duke Williams

whenever you fat finger the subject line, drop me a note. You won't be bothering the admins, because I am not one. I am happy to fix it.

ps, if we don't catch it immediately, the second and subsequent posts all carry the fat finger title. Can't fix that...

[Stuart F.]

Re: For Stu Fox and Duke Williams

Thanks Don for your advice. With me it was no big deal. There aren't too many Fox's on the board so I picked it up quickly, and I certainly don't fault anyone but myself. Just glad that Jeff got his engine running. I was particularly interested due to his car is another 63 L-76 like the one I've lived with for over fifty years.

Thanks Jeff. We all learned something, or re-learned something from your problem. Just wish someone could have answered my associated question about whether the C-1's have power to the coil ONLY through a ballast resistor (no 12 volt source through the starter upon START).

Stu Fox