Author Topic: 350 olds, runs bad when warmed up  (Read 318 times)

sammons

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Re: 350 olds, runs bad when warmed up
« Reply #15 on: March 09, 2019, 06:04:58 PM »
Check top of coil tower for a hairline crack. Then check coil wire boot for hole, or coil wire for bad insulation.  If you can't find any flaws, wait till it gets good and dark outside. Pop hood, start and look to see if any sparks are jumping out and where. You shouldn't get any shock there unless its wet or something is cracked or a bad insuator.

EDNY

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Re: 350 olds, runs bad when warmed up
« Reply #16 on: March 09, 2019, 08:50:25 PM »
Make sure the motor has a solid ground to the body and frame.  Sounds like you are making contact with the body when messing with the cap and it's looking for a ground (AKA You!)
33 Chevy 5 Window, 34 Chevy 3 Window, 37 Chevy 4dr sedan

28chevyguy

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Re: 350 olds, runs bad when warmed up
« Reply #17 on: March 10, 2019, 12:03:05 PM »
Used the old windex with ammonia trick on the cap and wires last night,  the new coil wire from napa was made incorrectly , the electrode wire was folded back and sticking out of the boot !!    Swapped wire and no more sparks . 

the window and ammonia trick is super useful...  I imagine repair shops can't use that trick during the day !!!

Car still does the same thing after warmed up.  Im going to add another ground from engine to car just for good luck .

I'm going to unhook the main + wires going to the coil and measure the voltage , should be around 9 volts.  Going to look into replacing this wire as well being that it is original and soft , the copper is brown and probably not the greatest conductivity. Also should re-check and compare the voltage when the car starts acting up .

I believe there is a  built in balast resister somewhere leading from the + coil wire  that i was told runs into the bulk head.   Also a "R" wire coming from the starter to the coil to give full power while starting,   the car starts right up so i doubt that is a the culprit.
Being a points setup there should be a ballast resister somewhere... maybe it is breaking down.

28chevyguy

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Re: 350 olds, runs bad when warmed up
« Reply #18 on: March 10, 2019, 02:05:12 PM »
think I might have found it.  The coil reads 4.9 - 5 volts in the run position and running goes down to 4 volt.  when being revved it seems to drop to around 3.5 volts .     im starting to think someone long ago did some funny stuff with the coil wires ,  Im reading one goes to the start "R" terminal for 12 volts at the coil  cranking only.  The other wire should come from bulkhead with a resistor somewhere in line .     It seems both crappy wires go down towards the starter and one is taped up, some big cobb job lookin thing.

gotta jack the car up and get down under there or im thinking just run a 12v switched wire to a ballast and to the coil and be done with it.    I was under the impression the coil should have around 9 volts .  Pretty amazed the car even runs at all like this .

**EDIT,   Unhooked , i do have 11.9 volts at the coil wire .
« Last Edit: March 10, 2019, 02:29:41 PM by 28chevyguy »

28chevyguy

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Re: 350 olds, runs bad when warmed up
« Reply #19 on: March 12, 2019, 09:29:01 PM »
I guess it was the condenser ,   buddy hooked up a cap at the coil and it seems to be fine now.... I just cant believe it …. not going to argue with the Oldsmobile she rarely asks for much .    had it running for over an hour and all seemed well .  thanks for all the help and suggestions .

chopper526

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Re: 350 olds, runs bad when warmed up
« Reply #20 on: March 12, 2019, 10:09:17 PM »
Good for you!!! I know how frustrating this stuff can be! glad your Olds is up and running 100% That's pretty amazing to me. I don't think I can ever remember one going bad.
Tighten it up til it strips, then back it off a quarter turn

TFoch

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Re: 350 olds, runs bad when warmed up
« Reply #21 on: March 13, 2019, 07:09:12 AM »
I had a condenser go bad in a 66 Chevy II I used to have.  This one just quit while getting off the hi-way on an off ramp.  Went to the auto parts store and got a new one and drove it home.  Glad you found it!
Working for a living gets in the way of finishing my car

EDNY

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Re: 350 olds, runs bad when warmed up
« Reply #22 on: March 13, 2019, 08:09:33 AM »
If I remember correctly with a bad condenser the car barely runs at all, just spits and sputters warm or cold.
33 Chevy 5 Window, 34 Chevy 3 Window, 37 Chevy 4dr sedan

ghost28

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Re: 350 olds, runs bad when warmed up
« Reply #23 on: March 13, 2019, 05:30:53 PM »
I remember grabbing one after my brother charged it up. He thought he was so funny.

sammons

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Re: 350 olds, runs bad when warmed up
« Reply #24 on: March 13, 2019, 06:31:04 PM »
28 Chevy, glad you got her up and going. I've never had one go bad as you described, but have heard of such. Most of mine either worked or didn't. The '58 Vette had one go bad when warm, but it would just die.

Ghost, lol, high school days. I was never around capasitors(condensers) other than cars. They had them in dist, along coil, radio and generators. Freshman year electronics class was a shock fest by a couple teachers assistants. You learned real quick not to catch anything they thru at you ;D 

We reclaimed a lot of parts from old electronics, and I did help the smarter assistant build a "safe" capasitor discharge set up (instead of the screwdriver short out) Box with on/off, volt meter, a couple inline resistors, two insulated aligator leads. When I became teacher assistant (jr/sr years), I only did it once..... to my assistant trainee ;)

28chevyguy

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Re: 350 olds, runs bad when warmed up
« Reply #25 on: March 13, 2019, 08:36:05 PM »
I dropped it off at my buddys shop.  he says he started it up , let it run a little and apparently it just died and wouldn't start back up , they pushed it in ,  let it cool down a little got it started , then hooked up the (what I thought was the RF cap ) to the NEGATIVE at the coil and apparently that was the magic touch, said it instantly started running better.  He didn't actually pull the cap and swap the condenser.    I originally unhooked this supposed RF cap on the coil thinking it could be causing the issue , im 99% sure it used to be on the POSITIVE side of the coil .    I dont understand .   all he did was hook that up to the neg / coil and apparently its all good???   I had it running for an hour and 10 minutes afterwards, kept driving around , parking , driving ... the dang thing wouldnt act up .  When i got the call that car was all fixed I would have bet you every dime in my pocket that it didnt fix the problem and he probably didnt let it warm up long enough... you know ... thinking the worst.      I am still reluctant to drive it too far as of right now , time will tell....

 probably one of the strangest things I have seen so far .    makes ya feel like a noob .

chopper526

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Re: 350 olds, runs bad when warmed up
« Reply #26 on: March 13, 2019, 09:43:16 PM »
Well, it's all good news in the end. I know it had to be weighing on you.

....I learned about magnetos the hard way......... :o
Tighten it up til it strips, then back it off a quarter turn

EDNY

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Re: 350 olds, runs bad when warmed up
« Reply #27 on: March 14, 2019, 08:14:35 AM »
Just thinking if it was a SBC I would just drop in a "one wire" HEI distributor ... I suspect there is one to fit your Olds?
33 Chevy 5 Window, 34 Chevy 3 Window, 37 Chevy 4dr sedan

28chevyguy

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Re: 350 olds, runs bad when warmed up
« Reply #28 on: March 14, 2019, 09:11:24 AM »
Yup,  that is the back up plan …   they make HEI for anything... I even got one for a ford 302 a few years back.

EDNY

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Re: 350 olds, runs bad when warmed up
« Reply #29 on: March 14, 2019, 03:39:12 PM »
Yup,  that is the back up plan …   they make HEI for anything... I even got one for a ford 302 a few years back.

There must be one in your local salvage yard.
33 Chevy 5 Window, 34 Chevy 3 Window, 37 Chevy 4dr sedan

 


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