Hey guys. My 389 has been on the fritz. Maybe u guys have an insight or similar experience. I've researched this but only came up with threads about half of my issue Sorry in advance for long write up but.. Here's my set up; 65 bonneville factory rebuilt 389 with edelbrock 650 carb. Installed pertronix lll about 4 yrs ago. 400 trans. Last time I timed it was set around 12 and ran perfectly. Car has ran great and started great for the past 5 years with no issues. So, I only get the car out on the weekends or every other weekend. Took it for a drive a month ago, all normal, exit freeway and Come to stoplight. Car starts to have a rough idle and is fluctuating from idling good to rough bogging idle, but is fine when I lightly brake stand it to feed it a little fuel and bogging stops and runs fine. Kinda still Boggs at idle before I get home. Just kept on the gas to keep Rpms up until I got home. A week later, same story. Last week: start car, cruse down to get coffee down the street and runs fine. Go to leave coffee shop and I start the car and bogging rough idle starts. I start driving away and motor starts pinging the whole way home. Along with rough running and barely staying running. Never stalled though. Plugs look good, light brownish. Normal color. Car wasn't and hasn't been running rich. Inside cap and rotor very very clean. Figured it may have been the vacuum advance. Looked original. Replaced it and gave the **** test to the old vacuum advance and it was bad. Started car and still had rough idle. When I checked the timing i noticed on the timing light, that when the car would hesitate or kinda "miss" while idling the light flashing wouldn't be consistent flashing. It fluctuated with the miss. Which leads me to think its the pertronix module because when the car suddenly idles good, the flashing is consistent like it should be. But then idles rough again. It can't seems to stay running rough or fine. It's jumping back n forth. I put the car in gear and it would run worse or stall. But isn't hard to start. Now there's no manifold vacuum port on this intake to use. The factory Pontiac 2 tubes that Coke up to the factory style carb are gone and those are plugged. Vacuum advance line came from (as long as I've had the car) the carb port on p***enger side. Since it ran bad after changing the va, I read that the proper side for VA is the driver side port. Switched them and tried adjusting timing and no difference in idle roughness. For kicks I put a new fuel pump in because I noticed fuel was very little in filter and figured maybe it was starved too. No change. I apologize for the long write up but trying to eliminate possibilities and narrow it down. Could bad vacuum advance cause the rough idle at first and mess up the pertronix? Does it sound like the pertronix is going bad? Thinking of pulling them and sending to pertronix to test it. I'm at the basic frustrated point of a lost weekend day/money spent/no progress point, so any info would help. Thank u guys
"I start driving away and motor starts pinging the whole way home." While you are eliminating things...are you sure there is coolant in it? Don't trust the overflow bottle, or the gauge, look in the radiator.
Yes there's coolant. About 2" low from the top but it's never ran over 185. Even today while messing with timing etc, it was idling for 30 mins and never went hot
"Took it for a drive a month ago, all normal, exit freeway and Come to stoplight. Car starts to have a rough idle and is fluctuating from idling good to rough bogging idle,but is fine when I lightly brake stand it to feed it a little fuel and bogging stops and runs fine. Kinda still Boggs at idle before I get home. Just kept on the gas to keep Rpms up until I got home." This ^ leads me to believe that you may have a bad or out of adjustment float in your carb.. Have you check that recently? BTW, I grew up in Tujunga.
Put the points back into the distributor to possibly rule out a failing Pertronix unit. I like using points myself for my old cars, they never give me any trouble.
Run a byp*** wire from ignition switch to ignition to make sure that you are getting 12 volts. had a truck years ago that was doing the same thing and found out it was a bad wire to the coil. Fuel or fire and sounds like fire.
Loosen gas cap to make sure that fuel tank is venting properly. Check fuel line from inlet side of pump clear back to the tank. Look for dried out,kinked, split or cracked rubber hoses, or rubbing against steel lines. Check the top sides of the lines especially where they're not easily seen. Check the distributor mechanical advance for stuck or broken advance weights or return springs. Get a vacuum gauge and determine which carburetor ports are full manifold vacuum and which are ported (off idle) vacuum.
All great points guys. I have not checked the carb yet, I'll go thru that. I did put I new fuel filters the other day. I was going to pick up a set of points and coil to try that next as well as finally buying a decent vacuum gauge. I feels like such a minor simple problem but it's teasing me. Will report back
I'd agree with the roadster1927 ....if the timing light incident and it running poorly happened at the same time...it's ignition..swap in a set of points and see if that fixes it....I swear by points too like others mentioned...
"The timing light not flashing evenly ! That is all I am going to say! Good Luck, Gary" ============= I agree 100%. That is an Extremely su****ious symptom.And a very important clue An Unsteady ignition spark pattern is never good. If it ain't the timing light, something about the ignition system is way off.
....I had a 455 pontiac that was acting some what like yours,...make along story short the coil was bad,it would ohm out good when cold as soon as it got warm it would act up,...changed the coil motor ran great,...miller
You're seeing erratic timing, suspect the Pertronix may be bad, but replacing other parts? That makes no sense to me. Swap out the Pertronix for a new one, or a set of points if they're readily available. Then recheck to see if the timing is no longer erratic.
There's a couple of things noted here that you could also check. https://m.youtube.com/watch?autoplay=1&v=jxrhgUa11-M
I am in Nor Cal. I spent last 30 yrs working on 389 Pontiacs. If you want to call me. 831 724 4080. I am sure we can figure it out. I am bringing my 64 GTO out of storage and back to life now. I built my first 389 when I was 14 so I hope I can help you a little.
Pulled pertronix to send in and have them Check out the module and coil. Picked up all the parts for points condenser etc however non came with mounting screws and pertronix screws won't work. In a holding pattern until next weekend u fortunately. Thanks for responding guys! Will update
Got a little update. I said before the car came with an ignitor 2 set up. And I put an ignitor 3 in it shortly after I purchased it. Well, I would only ***ume it was done right because the car ran great. And after installing the ignitor 3 I've had no troubles for years. Well I guess the wire to the coil is the original resistance wire which is not a full 12v while running. And the tech at pertronix said my symptoms were due to not enough Volts to coil. And being that the car only gets out once or twice a month for short driving times, it wouldn't be affected as quickly and would start acting up. After testing volts it was very low. My battery isn't 100% charged but enough to start the car. But that's what I'm going for right now. I mailed in the module and coil to pertronix to be tested anyway. And will either have to install their power relay or rewire for a solid 12v to coil while running. After all this I'll let ya know if that's what ails me Thanks again guys!!
So pertronix sent me a new module and coil. Said there was a transistor failure in the module. I ordered their power relay and got everything installed. Now the kit comes with a diode to install inline on the #4 wire going to the alternator regulator on the firewall. On my regulator there wasn't a wire going to 4, but to #3 and another to F (I believe). I installed the diode inline on 3. The car started and ran great. Once it kicked down I checked the timing and set it to around 12. But once it kicked down I heard a chirping from I think the alternator. The gauge needle was bouncing with the chirp. And it was a consistent chirp. Is this due to the diode being on the 3 wire? What would cause this? But the car seems to run fine
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