Main IndexAuto Repair Home Search Posts SEARCH
POSTS
Who's Online WHO'S
ONLINE
Log in LOG
IN







1949 Chevy 3/4 Ton spark problem


  Email This Post



tinkering
User

Sep 10, 2013, 5:10 AM

Post #1 of 25 (360 views)
Shortcut
     1949 Chevy 3/4 Ton spark problem  

The motor in my 49 3/4 ton is a 235 CID out of a 54 Chevy. The motor won't fire. I have strong spark from the coil lead to ground when I open the points. It is blue and it snaps a strong 1/2 inch plus but when I turn the engine over with the starter, the spark from the coil lead to ground is 1/6 inch weak. What the heck am I missing here? I have tried a different (used) coil and condenser but it does exactly the same thing. Why would we have such a strong spark when opening the points by hand and then nearly nothing when turning the engine over with the starter?


Hammer Time
Ultimate Carjunky / Moderator


Sep 10, 2013, 5:41 AM

Post #2 of 25 (351 views)
Shortcut
     Re: 1949 Chevy 3/4 Ton spark problem [In reply to]  

Is this thing running a 12v battery?
If so, just for test purposes, try running a jumper wire directly from the battery the the + side of the coil and see if that changes anything.




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



tinkering
User

Sep 10, 2013, 6:03 AM

Post #3 of 25 (348 views)
Shortcut
     Re: 1949 Chevy 3/4 Ton spark problem [In reply to]  

That is a heck of an idea. Thanks
It is still 6 volt. Yes I will run a jumper to the + side of coil. Should I undo the feed wire from the ignition switch first? If I do that it will isolate potential problems in that part of the circuit. Could the starter be drawing too much and robbing the ignition?
It is still 6 volt but I have jumped it with a 12 volt boost; I know that is not a good idea but I have done it.
I will get back to you when the sun comes up and I have tried the 6 volt jumper.


Hammer Time
Ultimate Carjunky / Moderator


Sep 10, 2013, 6:10 AM

Post #4 of 25 (345 views)
Shortcut
     Re: 1949 Chevy 3/4 Ton spark problem [In reply to]  

Are you sure it has a 6 volt coil? The 235 is a 12v engine.

I know the 12 volt systems are designed to start on 12v but run on 8v through using a resister wire from the ignition switch. I'm not sure about the 6v systems. That is the idea behind the jumper wire though, testing that resister wire.




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



tinkering
User

Sep 10, 2013, 6:32 AM

Post #5 of 25 (343 views)
Shortcut
     Re: 1949 Chevy 3/4 Ton spark problem [In reply to]  


In Reply To
Are you sure it has a 6 volt coil? The 235 is a 12v engine.

I know the 12 volt systems are designed to start on 12v but run on 8v through using a resister wire from the ignition switch. I'm not sure about the 6v systems. That is the idea behind the jumper wire though, testing that resister wire.



tinkering
User

Sep 10, 2013, 6:35 AM

Post #6 of 25 (342 views)
Shortcut
     Re: 1949 Chevy 3/4 Ton spark problem [In reply to]  

In Reply To
Are you sure it has a 6 volt coil? The 235 is a 12v engine.

I know the 12 volt systems are designed to start on 12v but run on 8v through using a resister wire from the ignition switch. I'm not sure about the 6v systems. That is the idea behind the jumper wire though, testing that resister wire.



The original engine was a 216; it is a 6 volt engine. I ran the 235 in there successfully for a bunch of years with the original 6 volt ignition wiring and components. That makes me think there is no resistor wire; that the system runs and starts on 6 volts. Maybe I'm wrong there; did they use a resistor wire with 6 volt systems too? The funny thing is that there is a super strong 1/2 spark from the coil lead to ground when I static spark it by opening the points manually (with the ignition switch on) but when I turn it over with the starter, the spark is extremely weak (1/16" with no snap).


(This post was edited by tinkering on Sep 10, 2013, 6:37 AM)


Hammer Time
Ultimate Carjunky / Moderator


Sep 10, 2013, 6:37 AM

Post #7 of 25 (340 views)
Shortcut
     Re: 1949 Chevy 3/4 Ton spark problem [In reply to]  

Again, is it a 6v coil or a 12v coil?




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



tinkering
User

Sep 10, 2013, 6:40 AM

Post #8 of 25 (338 views)
Shortcut
     Re: 1949 Chevy 3/4 Ton spark problem [In reply to]  


In Reply To
Again, is it a 6v coil or a 12v coil?



It is a 6 volt coil.



Hammer Time
Ultimate Carjunky / Moderator


Sep 10, 2013, 6:42 AM

Post #9 of 25 (334 views)
Shortcut
     Re: 1949 Chevy 3/4 Ton spark problem [In reply to]  

Run the jumper wire test.




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



tinkering
User

Sep 10, 2013, 6:43 AM

Post #10 of 25 (332 views)
Shortcut
     Re: 1949 Chevy 3/4 Ton spark problem [In reply to]  


In Reply To
Run the jumper wire test.



Right on! I'll let you know.



Tom Greenleaf
Ultimate Carjunky / Moderator


Sep 10, 2013, 3:37 PM

Post #11 of 25 (305 views)
Shortcut
     Re: 1949 Chevy 3/4 Ton spark problem [In reply to]  

It can or might not matter. 12v is ballasted down to 6v if a 12v system. All were till the end of that. Vehicles were 6v ignitions till about 1969.

If you have spark at all this will run. Not a game - own stuff older than this w pos ground that is a mind bender,

T
_________________________________________
Long retired now


Hammer Time
Ultimate Carjunky / Moderator


Sep 10, 2013, 3:51 PM

Post #12 of 25 (299 views)
Shortcut
     Re: 1949 Chevy 3/4 Ton spark problem [In reply to]  

The voltage is reduced down to about 8 volts, not 6 and Chevy went to 12 volt in 1955.




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Discretesignals
Veteran / Moderator


Sep 10, 2013, 4:50 PM

Post #13 of 25 (294 views)
Shortcut
     Re: 1949 Chevy 3/4 Ton spark problem [In reply to]  

You could always use a mechanic's stethoscope to check the dwell angle.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Sep 10, 2013, 4:50 PM)


Hammer Time
Ultimate Carjunky / Moderator


Sep 10, 2013, 5:29 PM

Post #14 of 25 (289 views)
Shortcut
     Re: 1949 Chevy 3/4 Ton spark problem [In reply to]  

LOL




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



tinkering
User

Sep 10, 2013, 10:00 PM

Post #15 of 25 (281 views)
Shortcut
     Re: 1949 Chevy 3/4 Ton spark problem [In reply to]  

I guess I was mistaken about the system being a positive ground. My 23 Model T is the positive ground. Sorry for the misinformation.
I don't think there is a resistor wire or block in the 6 volt system. The auto parts store hasn't got a listing for anything. I think it is start with 6V and run with 6V. I have found that the spark problem is intermittent, so I have purchased new ignition parts to install one at a time. I will be checking and cleaning up all of the connections at the same time. When I ran the jumper wire test to the coil, I removed the feed from the ignition switch to the coil. I achieved a good strong spark from the coil lead to ground but then it disappeared again, so I am going to start by replacing the points and condenser, and other major things. When I get it going with the jumper wire, I am going to clean and tighten up the wires and connections working towards the ignition switch and ammeter etc. There must be a major voltage drop or more in the system.


Hammer Time
Ultimate Carjunky / Moderator


Sep 11, 2013, 6:05 AM

Post #16 of 25 (274 views)
Shortcut
     Re: 1949 Chevy 3/4 Ton spark problem [In reply to]  

Before you just start throwing parts at it, you first need to determine whether it's the power supply side that is dropping out or the ground pulse from the other side of the coil. You may be having an issue with the coil itself.




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Sep 11, 2013, 6:06 AM)


tinkering
User

Sep 11, 2013, 10:18 AM

Post #17 of 25 (270 views)
Shortcut
     Re: 1949 Chevy 3/4 Ton spark problem [In reply to]  


In Reply To
Before you just start throwing parts at it, you first need to determine whether it's the power supply side that is dropping out or the ground pulse from the other side of the coil. You may be having an issue with the coil itself.


The points look well worn so I will change them out, and the condenser at the same time; I have this feeling about them. While I do that, I will be checking the wire, insulator, and connections on the ground side. If that does it, I will return the coil to the store. Otherwise, the new coil will be the next thing I put in. Coils may be a less common cause but in the past I have had a no start situation solved by installing a new coil. I have disconnected the power supply side at the -neg terminal of the coil, and I have run a jumper from a separate battery; so when I get it running in this configuration, I will work my way back up the power supply side; in case it is a compound thing. I would like to give it new cap, rotor, and plugs but they are not causing this poor spark condition at the coil lead.

Thanks



Hammer Time
Ultimate Carjunky / Moderator


Sep 11, 2013, 10:34 AM

Post #18 of 25 (265 views)
Shortcut
     Re: 1949 Chevy 3/4 Ton spark problem [In reply to]  

Throwing parts at it is not testing.




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator


Sep 11, 2013, 10:35 AM

Post #19 of 25 (264 views)
Shortcut
     Re: 1949 Chevy 3/4 Ton spark problem [In reply to]  

Hammer - Try replying to things you know about which isn't much!

!!


Tom
_________________________________________
Long retired now


Hammer Time
Ultimate Carjunky / Moderator


Sep 11, 2013, 10:41 AM

Post #20 of 25 (260 views)
Shortcut
     Re: 1949 Chevy 3/4 Ton spark problem [In reply to]  

Off your meds again huh Tom?




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



tinkering
User

Sep 11, 2013, 11:11 AM

Post #21 of 25 (255 views)
Shortcut
     Re: 1949 Chevy 3/4 Ton spark problem [In reply to]  


In Reply To
Throwing parts at it is not testing.

That is true. I think the points should be replaced because of the visual inspection, and I have always had the tendency to change the condenser at the same time as the points. Because of the intermittent nature of this, I feel that the best thing to do now is check, clean, and secure all of the conductors, insulators, and connections. Then a test light or meter reading indicating a voltage drop can be trusted. The resistance between the primary posts on the coils is about 1.2 ohms (close to the value of an old coil I have here). The resistance values of both of these coils are very close to one another. I will compare them to the resistance of the new coil I have. Sometimes I get lazy and just change out a part so I can hopefully get on with other tasks (I am hoping to get a garage pad poured before the snow flies here. I am trying to get this truck started so I can jockey it out of the way. I trust I can remain patient Crazy




Hammer Time
Ultimate Carjunky / Moderator


Sep 11, 2013, 11:17 AM

Post #22 of 25 (252 views)
Shortcut
     Re: 1949 Chevy 3/4 Ton spark problem [In reply to]  

It won't hurt to replace the points and condenser but you really need to figure out which side of the circuit is dropping out if any.




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



tinkering
User

Sep 11, 2013, 11:31 AM

Post #23 of 25 (250 views)
Shortcut
     Re: 1949 Chevy 3/4 Ton spark problem [In reply to]  


In Reply To
It won't hurt to replace the points and condenser but you really need to figure out which side of the circuit is dropping out if any.

That is great advice. I will check everything from the +post of the coil, through the points and condenser, all the way to ground. I will post any voltage drops, and readings while cranking, if I have to get the meter out again.



tinkering
User

Sep 11, 2013, 5:06 PM

Post #24 of 25 (244 views)
Shortcut
     Re: 1949 Chevy 3/4 Ton spark problem [In reply to]  

CoolI made up a new primary ignition feed wire from the +coil post to the distributor. The the primary ignition wire insulated connector that goes into the side of distributor (the points and condenser wire connect to it in there)was loose and dirty (not any more). I installed the new points and condenser. I have a good 3/4 inch blue snapping spark from the coil wire to ground when turning it over with the starter (hooray!). Because I installed the new wire, beefed up the insulated connector; installed points and condenser, all at the same time, I am not sure what the main instigator was, so I will venture to say that there was a voltage drop over that primary ignition insulated connector; I also suspect the points just because they were quite burned, and the condenser could have been adding to it.

The motor fired. I got it to run but had to keep priming it through the carb. The fuel pump is not delivering to the float bowl. Rot and mice have consumed major portions of both oil lines; I need to replace those before I can run the motor for any length of time. The water pump is leaking (not enough to stop me from moving the truck across the yard when I get the oil lines on.)

I still have the separate battery and jumper wire feeding the coil. I need to work my way back up the positive feed side of the power supply through the ignition switch and ammeter, to the main connection on the starter; making sure the connections are all cleaned and tightened, and that there is no missing wire insulation.

Unfortunately I didn't get any of those voltage measurements taken at the coil etc. while cranking the starter. I would have liked to have seen what the reading were too. Maybe we can get those after we get the second battery and the ignition jumper wire out of there.

I did not replace the coil, rotor, cap, or plugs.

IT'S RUNNING!


Hammer Time
Ultimate Carjunky / Moderator


Sep 11, 2013, 5:33 PM

Post #25 of 25 (240 views)
Shortcut
     Re: 1949 Chevy 3/4 Ton spark problem [In reply to]  

Glad to hear you got it resolved.

Closing this question as solved now to keep the spammers out.




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.





1949 Chevy 3/4 Ton spark problem


  Email This Post
 
 






Latest Forum Post
Hi, I am not car savvy. I have a 2003 Honda CRV, and the rear windshield wiper d...
1963 FORD Falcon / installed new tank and sending unit. Gauge shows past full an...
Hi, Ii have problem with my chevy cruze 2011, my car just 37000km. Before 2 week...
Re: 2000 Buick Century 3.1L 120,000m - I‘m having problems replacing the ...
Actually the only way I could get any pedal at all (and enough pressure to turn...
OK, so I need to reopen this thread and take back my kudos from yesterday, sorry...

Feed Button


Used Car Search
Used Car Price Ranges:
Under $5,000
$20,000
$35,000

$10,000
$25,000
$40,000
$15,000
$30,000
$45,000
Over $45,000
Search used Cars By Manufacturers:
Used Acura
Used Audi
Used BMW
Used Buick
Used Cadillac
Used Chevrolet
Used Chrysler
Used Dodge
Used FIAT
Used Ford
Used GMC

Used Honda
Used Hyundai
Used Infiniti
Used Jaguar
Used Jeep
Used Kia
Used Land Rover
Used Lexus
Used Lincoln
Used Mazda
Used Mercedes-Benz

Used MINI
Used Mitsubishi
Used Nissan
Used Porsche
Used Saab
Used Scion
Used Subaru
Used Suzuki
Used Toyota
Used Volkswagon
Used Volvo
2010 Honda Civic
$15,770
2004 Jeep
$8,991
2012 Mustang
$22,990
1997 Honda Cr-V
$4,490
2010 Toyota Prius
$17,496
2010 BMW 328
$26,980




Automotive Forum Categories
Automotive Repair
Auto Body Repair and Refinishing
AC Auto Repair Help Forum
Automotive Wiring and Electrical

Auto Insurance and Car Financing
Automotive World
Brake Systems
Car Stereo Repair Advice
Car Troubleshooting
Engine and Car Noises
Engine Fault Codes
Engine Troubleshooting
Exhaust System Repair

Steering and Suspension
Tricks of the Trade
General Discussions
Car Shows and Events
The Bargin Bin
Motor Vehicle Inspection
Car Care Tips
Traffic Ticket Help
Car Racing

Gasoline, Motor Oils, Concept Cars
Remote Control Cars and Vehicles
Truck Repair
Truck Repair Advice


Truck Engine Repair
Truck Suspension Repair
Motorcycle Repair
Motorcycle and ATV Repairs

Motorcycle Body Repair
Motorcycle Clutch Repair
Motorcycle Engine Repair
Motorcycle Seat Repair
Car Forum Posts - Sitemap


Search for (options) Privacy