85rotarypower

Exhaust is not great, been told this is how 79's with the thermal reactor smell. definately not as "clean" smelling as the cat equiped cars, but not as bad as an open exhaust.

Also, tried the ground thing, didn't make any difference.

13x

Have you tried swapping the dizzy? On one fo our local cars you could see evidance that the spark was arcing all over the place inside the cap. Timing is square leading and trailing? Saw one where the trailing was firing before the leading .. other then that I have been reading as I have a similiar issue from a happy to shift after the buzzer 12A to a disgruntled little car lol

85rotarypower

I've been trying to track down this problem for some time. I swapped the points dizzy to an electronic dizzy thinking the points were the problem. Was cheaper than getting new points along with a dwell meter (which I don't have). That didn't solve it, and the cap and rotor were fairly new from my 82 which I didn't drive much more than 5000km. I've checked all the obvious and even the less obvious possible causes, with nothing changing.

I did however find out why the problem was getting worse. Turns out the spark plugs were part of the problem there. They looked alright when I took them out, but today I couldn't barely get the car to start. Found there was no spark on the plugs I had in the engine.

j9fd3s

iTrader: (3)

the reactor is tricky, its hard to get it to smell clean like a cat, but it does work, IDK my old 79 passes CA smog really easy, and well my nose isn't calibrated for it!

my 79 did a weird intermittent ignition thing that turned out to be the wire to the points. it was a huge PITA to find because the wire died on the inside, but the insulation was fine on the outside!

when you put in the 81 dizzy, did you bypass the ballast resistors?

13x

^ good point with the original wiring your being stepped down to 9 volts while the fb dizzy setup is 12

85rotarypower

Yes I bypassed the ballast resistors. It's possible that I do have an issue with wiring, but at this point I can't find it. I will check the wires from the ignitors to the coils though since I'm running those through stock wires.

85rotarypower

Well I figured I would post what ultimately fixed this problem, and I am somewhat ashamed about just casually ignoring the symptoms and advice from some people in the first place. This is a case where the problem could not be detected through visual inspection of the parts, and I have come across it before, just under difference circumstances. But the big fix cost me only $50, in the form of a brand new set of NGK BR7ET spark plugs. Just goes to show that even though plugs look perfectly good, that doesn't mean they function perfectly good.

I think I mentioned in this thread that I tried the old plugs I had from my 82 in this engine, they were BUR9EQ in the trailing and BUR7EQ in the leading (stock 2nd gen NA I think). These ran marginally better than the BR8ET that were in the engine when I got the car, but still stumbled like crazy at 5500rpm and above.

Between the new spark plugs and new exhaust (RB header to custom 2" exhaust with magnaflow mufflers) the car accelerates absoluely amazing. I never thought an otherwise stock 12A could feel so quick. The car feels like a good low 16 second car now, judging from experience with mid 16 second and mid 15 second cars of my past, which is admirable considering in stock form these cars seem to generally run in the very high 16's to low 17's.

RallyCV

Thanks for following up. The search function's kinda useless if nobody posts their solution.

85rotarypower

This is true that the search function is useless if nobody posts follow ups to their problems, hence why I did post my solution. Only hope it helps somebody else some day.

85rotarypower

Well, I have some bad news on this problem. Seems the stumbling has started to reappear again after about 1500km of driving. I have yet to pull the spark plugs again for inspection, but I did notice some carbon buildup on the contacts in the distributor cap, so I will probably just replace it and the rotor. There isn't much mileage on the cap and rotor, but they are about 7 years old and potentially developed invisible cracks or leakage around the posts. Either way, I hope to solve this real soon as I intend to do a track day with the car in about a month. Also, the last long drive I made with the car, the idle had gone up from a perfect solid 800rpm to a slightly stumbling 1000rpm, so I plan to go over all the vacuum lines again and recheck my idle mixture. Timing I know is dead on but doesn't like being advanced much at all, starts to spit and spudder a lot if I go any more than 10 degrees advanced at idle.

85rotarypower

Well I may be a bit closer to a cause of this problem now. Did some troubleshooting this weekend and I think I have narrowed the problem down to being an ignition problem. However, I have went over the ignition system so many times I doubt its anything with the distributor, coils, or wires. After my testing this weekend, I have found that the spark plugs are fouling up pretty fast, which could explain the fact that it ran great when I first got the new plugs in it, then slowly got worse and worse to the point its at now, which is the same point as I was at last year. Its stumbling bad above 5000rpm, regardless of engine load and throttle input.

After putting about 1500km on the current plugs this season so far, they have went from brand new to rather black and after the last run, even a little oil soaked. I found this by running the engine up to 7000rpm then instead of letting it idle for a few minutes before shutting down, I shut the engine down after idling for a few seconds. Biggest thing I notice about the act of running the engine that high, while coming back down the engine billows out blue smoke at an amazing rate, like I just started it up after fogging the engine for the winter. On top of this, the oil takes a little while to burn off as well it seems since it smokes for a good minute or two while idling afterward.

So in the engine, I suspect that my problem actually has more to do with the known oil control ring problem with my engine. I didn't think the engine sucking in a little extra oil would have a big effect on how it ran, but maybe its sucking in more oil that I think it is, enough to mess with the a/f ratios and causing enough carbon buildup to foul the plugs. If this is actually the cause of my problems, looks like a rebuild is in order. Can anyone confirm if my thinking on this is correct?