Iggyg00

Ok i was able to drive this car all the way down to ga from sc. Once i got there it was running good and the next day it started to miss while driving. Finally yesterday i got around to working on it and the following happens.

Before starting i noticed that the vacumme line to the distributor was off so i reconnected it.

go to start it and it either starts right away sputters and dies or runs for a little bit and dies. At one point it had a huge backfire out of the exhaust sounded like a shotgun.

what are the best steps to diagnose it?

I was thinking of pulling the plugs, then checking the wires, not sure how to check the distributor or coil (noticed that this was really hot last night), I also had to tighten the screws on the carb 3/4 of a turn).

One other question is what is the 2 green wires with the plastic connector on the end and a resistor in it? Noticed this isnt hooked to anything.

Please help as i need to keep this running and driving until the house is built.

brown7373

Did you just get the car, and drive it from SC to GA? If it is new to you, I would start by checking all the simple, obvious things. Look at the plugs, check the points, the dwell angle and the timing of the car. With a new (to you) car, there are lots of unknowns and the only way to be sure is to go through and check everything. With a new purchase, there is no way to tell what has been fixed with"duct tape and bailing wire" without methodically going through it.

I remember a 2 green wire with resistor on a 1970 Bonneville that connected to the transmission controlled spark advance. It was a switch that only allowed vacuum spark advance in high gear, unless the car was overheating. Most of those switches have been disconnected and vacuum advance is connected bypassing that.

MDchanic

If you drove it several hundred miles with the vacuum advance disconnected, and it ran well, then it's not surprising that connecting the vacuum advance might alter the timing to a point where it wouldn't run.

It sounds to me like, as brown said, you need to go over this car from top to bottom.
Do all the stuff you do when first getting a new car: Points, condenser, cap, rotor, wires, plugs, check function of vacuum and mechanical advance, check that vacuum advance unit is the correct one, check timing and dwell, check carb adjustments, check vacuum hose routing, replace hardened vacuum hoses, check for vacuum leaks on the way to the transmission modulator, change oil and filters.

Once you know that everything is set up right, if you still have a problem, then you can start figuring out what's wrong.

Post up some pictures, so that we can see what you're dealing with.

And, yes, that hanging plug is from the TCS. Ignore it.

- Eric

Iggyg00

if the vacume advance wasnt hooked up would that cause the plugs to foul since its sparking to late?

Before i drove it down the following was replaced:

1. Oil
2. Filter
3. fuel filter
4. spark plug wires
5. added 3 qts trans fluid
6. installed fan and shroud
7. hooked up all the vacumme lines to the correct ports
8. replaced broken dipstick
9. tightened carb to manifold bolts as there was a leak.

Im going to have to dig through the storage unit to get the oem service manual out.

thank you for the replies

defiant1

Sounds like the plug wires were installed out of firing order.... Verify that, adjust timing and go from there...

d1

Octania

Once i got there it was running good and the next day it started to miss while driving.
======================
So, it ran OK to good for quite a while then next day misbehaved?

Start with the ignition.
Got good spark at the end of the plug wires?
Sounds like a simple pts/ condenser/ cap/ rotor tune up will cure it

OR, with HEI, bad coil or module or broken/ breaking wires to the pickup coil.

You say the coil was hot- pts type external or HEI on the distributor?

Iggyg00

Ok a little more detail between history of the car and last night.

Bought the car around June 11 did not run but the engine rotated. The previous owner tried to put in a petronix kit in the current distributor and couldnt get it to work so went back to the old points but put the distributor 180 degrees off.

Once i got it home i rotated the distributor 180 degrees and replaced the wires and she fired right up.

what im worried about at this point is the distributor etc as i dont believe it is the carb but am going to rebuild it anyway as who knows when the last time it was gone through was.

This is what I noticed last night:

replaced the spark plugs all the old ones where black, rotated the motor by hand until it was at top dead center and pulled the distributor cap and it lined up at number 1 a little to the right but I have the timing set at 10@ at 1100 rpm per the manual.

there is a yellow and black wire plus another wire off a small cylinder on top of the coil going to the coil on the left side and a black wire going from the right side of the coil into the distributor.This wire has been cut and spliced with a but connector in the middle (im guessing the previous owner had to cut it for the petronix). Within the distributor where the black wire connects there is a red wire from another cylinder under the cap.

The black wire connecting to the left side of the coil is coming from a wire look with a big purple wire, regular green wire, and a black and red wire i believe.

Next I tried to start the engine last night with the following results:

1. turned the key engine starts and the minute i let off on the key it died
2. turned the key it started ran good for less than a minute and then randomly died
3. turned the key it started ran but missing randomly and died
4. Backfired like a shotgun. Im guessing this is the fuel that is not being burnt building up in the exhaust and then igniting

Can someon explain what all the wires connected to the ignition system are?

Is the black wire from the wire loom connecting to the left side of the coil the correct wire? (noticed with the ignition in the on position that this wire gets very hot)

Would i be better off to just say screw it and go with an HEI distributor?

Grace Stinespring-Welch

i would replace the distributor

MDchanic

Typical.


Good.


What makes you worried about the distributor. specifically?



There is no reason to do this if you have confirmed timing with a timing light (and your timing marks are good...).



Yellow wire comes from the starter solenoid to provide 12V to the coil while cranking.
Black wire to the firewall is probably the resistor wire that powers the coil - it should provide 8-9V while running. If the PO tried to run the HEI off of this wire, that's why the car wouldn't run.
Small cylinder is the radio interference suppression condenser.
Black wire to distributor goes to points & condenser, then to ground.



Yes, he probably did.



Cylinder under cap is the ignition condenser.



Sounds right.



Sounds like a bad spark symptom to me - I'd check the points and condenser.



Yes, it should be.
If the points are closed with the ignition on and the engine not running, it may get hot - check the voltage at the connection when this happens next time.



No. Diagnose cause of problems first, replace parts second, not the other way around.
Throwing parts at a problem only fixes it if you're very lucky and hit the right one by accident.

- Eric

svnt442

I had an issue with a distributor a long time ago. The car was running great and just up and died on me. I checked all the usual stuff and it checked out. Then I noticed that the rotor was 180 out...hmm.... Pulled the distributor and dropped it back in and tried to start it....same thing again. I did that 3 times before I noticed the half moon of missing teeth on the distributor gear. The cam teeth were sharp as well, but I was 18 and broke so all I did was get a reman distributor and run it.
I hope you don't have that issue, but if all else fails, check the distributor gear.

Iggyg00

I have ordered a new carb from smi and awaiting delivery. As soon as it is here i will be diving into the distributor and ignition system.

Tonight i am going to pull the distributor after marking its location and see if the gears are ok.

Also while waiting i am going to fix all the crappy electrical work someone did on the car.

oldcutlass

No where in here do I see a mention of dwell setting on your points.

MDchanic

Nope.

Or responses to my questions, or indications that he followed any of our advice.

- Eric

Iggyg00

I will be following all advice especially with the ignition system.

Ok questions:
How do i check points without the car running?
how do i verify that the wires are good?
how do i check the coil to make sure that it is good?
Timing was set to the spec in the book before the 300 mile trip.


Any help with this would be appreciated.

Again the car is not running so if i can check any of these items before i get the carb then i will.

MDchanic

Easier to check running, but...

First, check for voltage at the coil (+) terminal with the ignition on - should be 12V with the points open, about 9V with the points closed.

Next, connect a spark plug wire with a spark plug on it to the coil, disconnect the (-) coli wires, and connect a jumper wire to the (-) coil terminal.
Ground the spark plug, turn on the ignition, touch the jumper to a good ground, then quickly pull it away - you should get a good spark.
Do it again a few times, because it's fun.
No spark = bad coil.
Spark = good coil.

Next, pull the distributor cap and rotor.
Inspect them for damage or carbon trails.
Check resistance between the distributor wire (that used to be connected to the coil) and ground while opening and closing the points - should be 0Ω closed, ∞Ω open.
If you have resistance, the points are bad.

If the cap, rotor, points, and coil are all good, and you've got a good supply voltage, then the condenser is probably bad.


Run the car in a pitch-dark garage and look for stray sparks.

- Eric

Lady72nRob71

Just make sure you get the ignition working right before changing the carb for obvious reasons. Sounds like that is what your plan is but wanted to add this comment anyway.

Iggyg00

God I hate moving now I only need to spend a day of searching through the boxes for my meter to check all of that.

Iggyg00

MDchanic,

4.3 volts at the coil

spark plug does spark but it doesnt seem to be that good of a spark

distributor cap and rotor look good

opening and closing the points showed 0 ohm and infinity ohm.

what next?

Iggyg00

spark is no where near what this one looks like when he puts a new spark plug on

MDchanic

4.3 volts is too low. It should be double that.
Check the terminal on the end of the wire to make sure it is clean and secure, and check along the harness to be sure it hasn't been cut and spliced somewhere.
If everything looks good, then try running a jumper from the battery to the coil and rechecking the spark.
I really can't think of what else would make the resistance go up, aside from corrosion or a bad connection.

If increasing the voltage solves the problem, then you could run full voltage through a ballast resistor, like the Standard Motor Products RU11, which should work fine.

- Eric

oldcutlass

It almost sounds like a bad condenser. Also is the gap on your points .016?

Iggyg00

MDchanic,

So what you are saying is that there is either something possibly wrong with the ignition wire coming from in the cab or the connections are caroded?

yellow wire is only for 12v when the starter is going so when i had the ignition in the on position voltage was only coming through the ignition wire or black wire?

oldcutlass,
how do i check the gap on the points? is there an easy way of doing this without the car running?

how can i check the condensors? and by condensor you mean a capacitor or the round cylinders 1 on the coil and 1 inside the distributor cap?

Any other suggestions for tomorrow when im back out with the car?

oldcutlass

Yes, the capacitor, I would replace it with a known good one.

You would set the point gap with a feeler gauge and the points wear strip on the highest point of the distributor cam. You will need and allen wrench or the proper flexible tool.

Iggyg00

ok went back out today and did the following.

Coil looks good it was an issue with where I was contacting the - wire to on the car. with a clean area and no rust looks like the spark in the video.

Also checked the ignition wire again and with it disconnected from the coil I get 12.06 volts, but with it connected with the capacitor on the coil, the wire from the starter, and the ignition wire on the + side I only get 4.3 volts.

What would cause this?

Also with all of them connected the ignition wire gets extremely hot when the ignition key is turned to on.

if the capacitor within the distributor is bad would this cause the 4.3 volts and the wire from the ignition to get extremely hot?

oldcutlass

If your points are closed you may get the low voltage and warm wire after a while.

MDchanic

Correct.


As OldCutlass said, CLEAN feeler gauge between points, rubbing block on peak of cam.
This is surprisingly difficult and annoying to do well.



The condenser is tough to test - if it will flow DC current, it is definitely no good, other than that, if everything else is bad, change the condenser.


Good.


It should be about 12V with no load, about 8-9V with a load.

Ohm's Law and all that.

The ignition supply wire is a nichrome resistor wire, which converts electrical current into heat.
In normal operation, the points are closed ⅔ of the time and open ⅓ of the time (car has 8 cylinders, ⅛ of a rotation = 45°, dwell angle is 30°, 30 is ⅔ of 45), so, overall, the coil is drawing power ⅔ of the time, which is the same as saying it is drawing ⅔ as much power while the engine is running as it is with the engine not running and the points closed.
The extra 50% of current flowing through the resistor wire when the engine is off is likely to heat it 50% hotter, and the coil, which is designed to shed heat when operating, but not when the points are constantly closed, will also warm up.
Since the circuit seems, from your voltage measurements, to be drawing about twice the current it normally would, it would make sense that the resistor wire would be that much hotter.

Make sense?



If the condenser was very leaky, it might pass enough current to reduce the input voltage noticeably.


- Eric

Iggyg00

Thank you!!!! MDchanic and oldcutlass

replaced the points and condenser with a new unit this morning and it works.

Next step get a new distributor lead to replace the spliced one currently on the car.

Now that I have the car running is there a way to dial in the point gap?

MDchanic

Of course.

Use a dwell meter to set the dwell angle to exactly 30°.

Start engine, connect dwell meter to coil (-) and ground (some units also connect to the battery (+)), open little door in the distributor cap, insert an allen wrench (or, better-yet, a flexible-shaft dwell adjustment tool), and turn screw until meter reads 30°.

You can buy dwell meters new, but I see them all the time at flea markets for $2 to $5.

- Eric

oldcutlass

Once you set your dwell, next you have to set your timing. Remember dwell will effect the timing, but timing will not effect the dwell.

Iggyg00

Ok set the dwell tonight. It was at 35 now its 30. runs a lot better.

checked the timing at 1100 rpm and it was right on the 10 degree mark.

checked the vacuum and its around 21 in/hg.

im going to play with the idle tomorrow and see if i can get it more smooth.

any suggestions on actual rpm in and out of gear?

MDchanic

Stock is 550 RPM in gear at idle, if I recall. Use your judgement to set it where it needs to be.

- Eric

JPMDaddy

You may have plenty of time waiting for SMI, after 7 weeks of waiting for parts, they allowed me to cancel my q-jet order...

Lady72nRob71

Good work - glad you got it running better!

Iggyg00

JPMdaddy,
I actually cancelled the order today as i had a 1604 edelbrock in the garage that just needed a rebuild. Once i find someone that can rebuild my 4mc i will send it out.

Lady72nrob71,
thanks its always nice when something gets figured out.

Hopefully i will get some pictures up here soon.

oldcutlass

Glad it all worked out.

Iggyg00

oldcutlass and mdchanic,

cant thank you guys enough.

Im sure i will have more questions as i get this beast back up to snuff.

MDchanic

You're welcome, naturally.

Ask away, we'll answer them if we can.

- Eric