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Guys and Gals

for the second season in a row I have an ignition problem. My 27 starts all day when cold and after reaching normal operating temp quits on me and after about 2 hrs of setting starts again.
When problem shows itself I get my multi meter out and have 6.25 volts at distributor and at coil when points open. When points close zero volts jumping across points when open get 6.25 volts. With igntion off and switch meter to ohms I measure 1.5 ohms of resistance which I am told indicated good coil. No spark at plug or coil secondary side. So gotta be coil, so switch and install other modern 6 volt with condenser still does not fire.
Both coils start engine when cold in morn both modern and original coils do not prevent stall and failure to start. I am ready to get a 3rd coil.
any comments appreciated.
Ken 45145

Looks like it is time to try another coil. Replace the condenser also.

Are you using a digital meter? If so try a 6v light bulb as a test light and make sure it lights where you had the 6v readings. I have found that a digital meter will read voltage but it will not light a test light. (not enough current)

Andy
yes, I have wondered about these meters and in fact just got a new one Saturday and also borrowed one as I noted different readings on same test with one headed for garbage. Ray got me thinking right and I broke down and got another coil and condenser for 1954 Chevy Belair and of course it started right up.
Ken 45145

Ray
Thank you very much for your help, I got a new coil and condenser for 1954 Chevy from Murrays and it started right up.
The coil is clearly marked 6 volt no external resistor required. This got me thinking (could be dangerous), why would it say that, I remember in the old days changing ballast resistors and not wondering anything.
Now my original coil, a 1927 version and what I really want, worked fine for a couple yrs and then after warm up started to malfunction. I got a 6 volt coil from ebay and used a condenser I got with tune up kit for 1927. Seemed to behave the same so I concluded it was something else. Winter came car and problem went bye bye.
This yr problem appeared and analysis pointed at coil and I did not want to accept that. So I posted and got your response so went and got a 1954 coil as you suggested to others.
So I wired it this way, ignition wire to positive primary coil post and negative primary coil post to points. I mounted the coil to the oil filter area with aftermarket bracket and bolted condenser down with the plate. Condenser wire connected to negative coil primary post along with wire to points. Installed secondary coil wire hit switch and it started right up. Now I did use the condenser from tune up kit for 1927 rather than 1954 condenser I got because lead was to short. I assume this is ok, Comments please. Why does the coils say no resistor required and should any 6 volt coil be OK or should future members read this and conclude they should buy a 1954 Chevy coil.
gotta go
Thanks Ray,
Ken 45145

I think that it is Because, the first several years that Chevrolet used a 12 volt system they used the same six volt coil as the six volt systems did. Six volts at the points don't arc and burn as bad as 12 volts going to the points. They used a dropping resistor attached to the firewall, later they used a resister wire going to the pos side of the coil.

On my 28 I mounted the 54 coil where the orginal coil was mounted with a modified bracket and like you connected the igntion switch wire to Pos and Neg to points. I attached the 54 condenser to the mounting bolt for the coil and the lead to the negative side of the 54 coil, high tension lead to top or distributor cap and, switch on, spark retarded, choke on, and stompped on starter switch and!....VARRROOOOMMM!

Ken, The resistor is in place to keep the coil from over heating. When cold the coil puts out a higher voltage and uses the full 6V input, if this higher voltage continues for a long period of time an internal circit breaker will shut the coil down. The resistor is in place, eather external or internal, to reduce the voltage to the coil after warm up and to prevent coil over heating. After starting, the entine does not need as much spark to continue running. The lower voltage to the coil extends the life of the points and other ignition system parts. Be sure to use an internal resistor coil.
When the engine shuts down, feel the coil if it is quite hot to the touch the automatic resistor is not working properly. A warm coil is normal.
Hutch

Guys and Gals
well, its doing it again. The new 1954 Chevy coil started it up this morn and upon hitting operating temp after shut down it will not restart no spark anywhere on secondary side. New multi meter indicated 6.25 volts everywhere on primary side with points open.
something is moving when hot or changing Help please.
Ken 45145

Are you still using the original ignition switch located on the steering column lock at lower end of dash panel? If so, when the shut down occurs place a jumper wire across the two terminals of the switch and see it the engine will start.

I once owned a '27 that acted much like yours. Vehicle would start when cold, run awhile, then sputter, backfire and quit when it got hot. Problem was, it didn't always act the same. The difference between our vehicles was that when the engine quite I didn't have 6 volts at the ignition side of the coil. I replaced the ignition switch and never experienced that problem again.

I took the my original ignition switch apart and found the contacts badly burned and distorted.

Oldie
gotta toggle switch installed under dash, also hot wire does not do it tried this out of frustration. I wonder if coil gets to hot sitting atop oil filter. Ordered a infra red temp gun to check temp but motometer indicates 180 or so and and does not seem to be overheating but did spit out overflow as I had water filled above core. earlier post discussed internal shut off, any guess appreciated.
Ken 45145

should I move coil? place an insulator between actual coil and top of filter?

the condensor has to be grounded good the 54 coils are mounted to the side of the head so if heat does not bother it there no insulator needed . hope this helps

Ken, You should not be reading any voltage at the coil with the points open only closed. check the wire from the negative side of the coil to the distributor, there may be a short as the wire goes into the bottem of the distributor or the insulator on the points is broken. I think your problem is in the distributor some place Not the coil.
After the engine stops running remove the wire to the negative side of the coil and use another jumper wire to a ground some where, as you touch the jumper wire to the negative side of the coil it should spark from the coil wire to ground.
Use the ohm meter to check current Between the negative distributor wire and ground. If you have current with the points open the problem is in the distributor.
I had a problem like yours on an MG B years ago, found the insulation on the wire as it entered the bottem of the distriubor was frayed.

It is not likely that a new coil and condenser would be defective so soon, so you need to look at the distributer. Make sure the gap is set correctly and that the insulation behind the points is not deteriorated.

With the ignition switch on, remove the center high voltage wire from the center of the distributor cap. Hold this wire near the block and with a screwdriver make and break the point contact and check for a nice strong spark.

While trying to start the engine view the ammeter, it should show movement as the points make and break.

We are assuming that the fuel system is okay?

Hi Ken

"Hot wire" - does that mean that you shortcutted the toggle switch? If not, have you checked the toggle switch or tried another one? On my 490 one of the previous owners had installed a toggle switch, because the key to the lightning and ignition switch was gone. Two weeks after I bought the car it suddenly stopped. My friend examined the toggle switch and it had burned. He believed the switch was OK for 12V systems, but that it didn't manage this use in a 6V systems.

Guys and Gals

OK here it is, looked inside distributor removed points and found the spring portion that slides over mounting bolt cracked in 2. Further removed bolt and found plastic insulator cracked also.

Conclusion when engine cold the cracked parts touched and when hot something moved the crack apart
fixed and installed new points it starts right up


Question, why was I able to read 6 volts after problem arose?

Answer, I concluded that Andys29 scenario above (meter reads 6 volts but not enough current to light the bulb) fooled me.

Comments please

Ken 45145

Also where can I get the plastic part that goes thru hole in distributor where points mount?

try "The Filling Station" or Ken Wallace.

I have made several from old ball point ink pen barrels. All you need is something that will not melt at normal distributor temps and will keep those electrons from jumping to the wrong metal parts.

That`s Gary Wallace

chev4cyl@charter.net

hoppy

I used a few fibre or plastic washers, did the job nicely.

Ray