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They used a nylon coated 36 tooth sprocket with the link belt from 1955 through '91. Finally changed to a 44 tooth single roller chain to drive Opti Spark distributor on the SBC2 reverse cooled motors used in Camaros and Impalas. You can not buy them as a replacement part any more as the Chinese sell cast iron sprockets for $3.86 on Rock Auto dot com.




Big Dave
 

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Discussion Starter #24
jay, you're that confident that it's spark related and not lack of fuel due to failing pump pressure or clogged filter?
It has a new pump and new filter. If I have time today, I will check points, swap condenser, and check timing. When I eyeballed it before, it was with the vacuum advance still connected. I'll re-do it from scratch, of course.
 

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Curious; after reading over most of your posts, I am wondering if heat or temperature is making a difference. Sounds like after it has sat for a while, or when cold, it starts up fine. Then after warming up for a few miles, it begins to stutter and fail.

I would normally suspect ignition/coil but I see you swapped that and received no results. Assuming fuel delivery and pressure is good, spark is a reasonable assumption.

I see you did points, coil, spark plugs, etc. but how about something simple like a bad plug wire? A bum wire could cause stuttering at cruise speed for sure, rough / low idle, etc. although in most cases it should only misfire and not kill the car as badly as you describe. But it is another thing to verify and eliminate as part of your troubleshooting...

Beyond that, other things that come to mind to check:

heat is boiling the fuel in the carburetor and running down the throat of the manifold possibly flooding the engine.

heat soaked starter + advanced timing could be causing running issues.

You got me really thinking on this so I may post other crazy theories as they come to me... :wink2:
 

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Discussion Starter #26
No starting issues. Starting fine, hot or cold. I can't work on it until next week, I'll report back.
 

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Discussion Starter #27
Finally found some time to work on the 65. Removed the points that I installed last tune up (Blue Streak, condenser built in), and swapped in a Pertronix 1181LSC. Wired it carefully according to the instructions. Unfortunately, this didn't fix things. It's actually worse. It will crank, and catch, then die as soon as I let off of the start setting on the key. I'm sad and frustrated. Going to get some help tomorrow and check spark on #1. Then, swap in my old (pre tune up) points.

One step forward, two steps back.
 

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Finally found some time to work on the 65. Removed the points that I installed last tune up (Blue Streak, condenser built in), and swapped in a Pertronix 1181LSC. Wired it carefully according to the instructions. Unfortunately, this didn't fix things. It's actually worse. It will crank, and catch, then die as soon as I let off of the start setting on the key. I'm sad and frustrated. Going to get some help tomorrow and check spark on #1. Then, swap in my old (pre tune up) points.

One step forward, two steps back.
Isn't that new symptom just that the pertronix requires a constant 12 volt signal? (not via stock resistive wiring)

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Discussion Starter #30
BA, thanks for the push on the 12v feed for the Pertronix. There were many reports of it working fine when wired to the resistance wire, so that's the way I tried it.

Progress today, however. I made a jumper from the battery to the coil+ (where the Pertronix pos lead goes), and the car started right up. Ok, I now know that the cloth resistance wire would not supply sufficient voltage once I released the key. Fabbed up a nice big gauge lead, and connected it to the switched IGN feed on the fuse box and the +coil lead. Ran it nicely through the factory harness mounts. Started it up, let it warm up, and took it for a short drive. The good news is that the car runs, and runs much stronger than before. Bad news is it is still breaking up when at cruise speed (45-60mph) and I get on the gas.

Next step will be to reset the timing, and check the idle speed and mixture. Hopefully that takes care of things. In addition to the (now replaced points), I did fresh plugs/cap/rotor last tune, but didn't do wires. Maybe I should change them out...

Thanks for the discussion, guys. I appreciate it.

Still might be bad gas. I put 3/4 of a tank of 93 no ethanol in it on the way home from work right before it started giving me problems. It was from a different station than I normally use. Maybe I should dump in 20L of fresh high test from my usual place. I initially suspected gas/gas delivery, that's what led me to the pump replacement.
 

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I don't know what kind of alternator you have (DN, SI, or CS) but the factory original was nothing more than a trickle charger for the battery. It didn't put out enough power below 3,600 RPM to power much more than the radio and the ignition. If anything else was drawing electrical power the GEN light would glow dimly to bright as the battery is discharging instead of charging.

Low voltage has a difficult time overcoming resistance. If you have bad spark wires the voltage will stay in the wire as it is the path of least resistance. As your RPM picks up the alternator starts to make power if you have a SI or and older DN alternator that raises the voltage to the coil and as a result increases the voltage to the plugs. The added voltage can over come the insulation that cracks and shrinks with age causing power that should be going to the plugs to leak away to the block.

If you have a one wire alternator (the CS version of the Delco-Remy alternator then you have full rated power just above idle (2,200 RPM). The rated power starts at 105 Amps which is about two to three times the rated power of a DN alternator.

Big Dave
 

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Discussion Starter #32
Bumping this thread because I have updates. After I did all the work, the Impala was starting, idling, and accelerating great. Unfortunately, it had to come home on the truck again. Same symptoms. Bucking at speed, then eventually, just dying when any acceleration was attempted.

Today, I got to work on it again. Took it out for laps on the country roads around my house. Accelerated hard, cruised at up to 70mph. Eventually, it began to cough. I brought it home, and plumbed up a temporary gas tank to feed the fuel pump. Thought this would rule out a problem with the tank or lines. Car behaved the exact same. As a last resort, I pulled the stock fuel filter from the carb inlet. No change. Still stumbling/coughing on acceleration at cruise speed.

It has to be the carb. I think the floats must be hanging UP. I'm going to rebuild it. I only use non-ethanol 91 octane, so I hope this clears things up.
 

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Could be a bad pump also. Rubber doesn't behave as you might expect when it is heated and cold rubber with a hole in it behaves differently than hot rubber with a hole in it. To isolate fuel lines tank and fuel pump try experiment again with an electric fuel pump temporarily wired into car. If it runs great and you have eliminated the tank and fuel lines you are left with only one suspect.

Big Dave
 

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Discussion Starter #34
I put a new pump on it, and just today ran it on an auxiliary tank to eliminate the stock tank/sock/lines as the problem. No change.
 

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Years ago, I had the plate that holds the points gum up at the pivot point (dried up oil). Easy to check. Take the distributor cap off and move the vacuum advance rod. It should return as soon as you let it go. Easy to fix. Squirt brake cleaner on the pivot point while moving the rod back-and-forth.
 

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Discussion Starter #36
I will double check that. I did verify the operation of the vacuum module when I did the Pertronix.

I'm going to put a fresh set of plug wires on it before rebuilding the carb, too.
 

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Discussion Starter #38
Yes, it has been crazy! This car has been the most reliable car ever, for two decades. The only thing I ever did to it was replace a voltage regulator after boosting it one spring. I need to get it back to that condition again. I miss driving with the top down! I will have more space and time, I just sold one of my other classics this morning.
 

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Have you checked the grounds on the motor?? I had a Buick GN that drove me crazy with similar issues. Any issues with headlights dimming, gas gauges acting weird, etc. ?????
 
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