1968polara383

Hi all,

Hope someone can help with this. When im driving my 68 polara 383 the strength of the lights both interior and exterior fluctuates quite badly. The ameter on the dash is also quite erratic. The dash lights dim and brighten at the same time as the headlamps. This isnt related to engine speed, they vary in brightness at steady speed. Now my car wont start having run perfectly when I last used her a couple of days ago. She turns ovee and ran for about two seconds, backfired and cut out. Now she just turns over with no signs of starting. Any ideas? Are these two issues potentially linked?

Any advice greatly appreciated!

Many thanks, Steve

mr340

I don't think they are linked. The light issue is probably a poor connection or corroded terminal somewhere in the electrical system. The starting problem sounds like it might be a timing issue. How many miles on the motor?

1968polara383

Thanks for the advice...... The engine has 58k original miles and runs sweet as a nut normally. I used her 2 days ago and she started and ran perfectly. Today she turned over but wudnt fire. I left her a while and checked to see if the dist cap had moisture in. All dry despite heavy rain over last couple of days. I checked fuel getting to carb ok and it is. As its now too dark to work on her, i havnt been able to check for spark at plugs. She did run for a couple of seconds but after backfire she just turns over without firing. It was a backfire from exhaust and not carb which is making me thing not a fuel issue, more elect/ mech. I didnt think of timing.... Without a breakage Im not too sure how the timing could change so suddenly but you obviously have much more experience with these cars than I do so I have got to consider it. I had a cuda a few years ago and the timing chain slipped as was worn... Hope this hasnt happened!!! Its a minefield at moment as new again to owning classic American cars. Very rare now in UK and local specialist help very hard to find! I will have to get the timing checked to start with as per your advice. I was thinking coil/ condenser maybe aswell?? Headache or what... At least Im learning though!

Do you think the lighting prob would originate between battery and prior to switch/ lighting circuit from symptoms or could I be anywhere? Does the lighting have a seperate earth? Sorry more questions but Im keen to learn from you guys as youve probably been there and got the t shirt!

Many thanks, Steve

TVLynn

I would check the connections on the back of the amp gauge

440roadrunner

Starting problem: What is the condition of the engine? Is it possible the timing chain has slipped?

Check that first, WITHOUT messing with dist. timing until you check it out

IF YOU know where the timing should be set (let's say you last set the timing at 5BTC) Bump/ wrench the engine until the timing marks are set WHERE THE TIMING was last set, IE 5BTC

Now pull the dist cap and or put a test lamp across the dist. negative terminal. Turn the key to run, engine off. Are the points open (light is on?) IF not, wrench the engine BACKWARDS just a few degrees, then slowly CW. STOP as soon as the points open. NOTE where the timing marks are. IF the timing is very much retarded, IE 5-10 AFTER TDC, you probably "slipped" the timing chain

Otherwise, suspect points/ condenser. How many miles on the ponts? Are they worn? Don't forget that as points wear, they retard the timing as they "wear towards closed." At some point, they may wear so much THEY DON'T EVEN OPEN or at least don't open on every cylinder

CHARGING SYSTEM: This can be a multitude of troubles. Suspect and check out the ammeter circuit AND THE bulkhead connector. READ THIS:

Article about the main feeds and ammeter circuit:



More articles:

I know the 2 wires from the dist. plug into the module and the other side plugs into the coil but my coil only has 1 terminal , what do I do ?


http://www.madelectrical.com/electri...p-gauges.shtml

A couple of the first things to check is the "voltage drop" across the ground and hot sides of the system relating to the regulator

So, key on, engine off. Hook one probe of your meter to the battery positive post, hook the other probe to the "key" side of the ballast resistor. Make sure the point are CLOSED. To check this, put your meter on ground, and coil neg. terminal. Voltage reading if points CLOSED is very low. If points are open, voltage will be close to battery voltage. Bump engine until points are closed.

Now with meter on battery pos, and "key" side of ballast resistor, and key in "run" what is the reading? You want to see a VERY low reading. Zero volts would be perfect, .2V (two TENTHS of a volt) is OK, and anything over 1/2 volt shows a problem.

The path you are checking is from the battery positive ---fusible link--through bulkhead--to ammeter circuit--to igntition switch connector--through switch--back out switch connector--back out bulkhead connector

Your top two suspects if the voltage is high is the bulkhead connector and the ignition switch and it's connector.

AFTER you get the car running properly, ALSO check the GROUND circuit of the regulator. To do this, get the engine running to simulate "low to medium cruise" with the battery charged and normalised. Now put one probe of your meter directly onto the battery neg. post, and the other on the frame of the regulator. Be sure to "stab" through any chrome/ paint/ rust. You are looking for a very low reading. Zero is perfect, over .2V (two tenths) is too much, and shows a ground problem in the regulator/ battery ground circuit.

If both these areas check out, if the ammeter circuit and bulkhead connector check out, change the regulator.

1968polara383

Thanks everyone for the replies! They are extremely useful to me as they are in laymans terms. I will print them off and slowly work through them. After all that effort, I went to her this morn and she fired up instantly and runs strong and smooth with no missfire. Wondering now if it was damp afterall and the backfire was just down to un burnt fuel.....tempted to investigate further but that old saying is nagging me.... If it aint broke dont fix it! Thanks again for all your help and best wishes.. Steve