I finished rebuilding the engine, its back in the car, yeah!
I'm having a missing / stumbling issue. The tach twitches a lot. The car has had this since I got it, but now I cannot keep it running
Being it's a 1979, it still has points.
I have replaced the plugs, cables, and the points.
I have gapped the points.
I cleaned the rotor and distributor.
Still has the full rat nest, almost all vacuum hoses are replaced.

here is a video of it running, I'm holding the choke partially closed to keep it running.


The plate the points are connected to has a lot of play. See this short video:

 

Oh, when I put the timing gun on it, the timing marks just jump around too, like the tach is.

 

That play is no good,leading points look burnt. Funky running,jumpy tach reading and erratic timing marks all related. Looking at those points leads me to ask if you replaced the condensers too... moot point.
There may also be fuel,carb related problems,may not,but having to hold the choke to idle is a clue not enough fuel being fed by idle circuit. Pursue the ignition faults,you know you have problems in this area. Fix this and the no idle condition may be minimized or able to be adjusted.

Couple ways to go here. You could try to find a used or rebuilt points distributor or you could source a used good condition FB distributor and coils and convert to electronic ignition which is superior to points. Everyone here will agree with this.
Better spark,easier starting and set it and forget it ignition timing due to no wear parts that change timing as they wear.
I recommend going FB dist/coils route,for what you pay for reman points distributor,you could have most of what you need to convert to the better system and never look back. Not a lot of rewiring associated with this,could get lucky and find dist/coils/ dist.igniter harness and be plug and play.
Will certainly change the way the car runs for the better.

 

I won't pretend to know the exact issue(s) from just a couple videos, but it appears you have multiple ones. Electrical, carburetor and probably ignition. Obviously the engine is not revving as wildly as the tack needle is bouncing (electrical). The stumble and rough idle I'd guess to be a combination of carburetor and ignition. I won't steer you away from switching to electronic ignition, it is a performance upgrade with lower / no maintenance when performing correctly. I think points get a bad rap however. I have multiple cars, still with points that I don't have any trouble with. Plus, I can still use the published manuals and factory literature to reference for diagnosis.

 

So, i took the distributor apart, cleaned all the connections, and now it runs like it did before I rebuilt the engine (leak of death). It still stumbles and misses some, but it will idle ~1k. The timing light follows the stumbles, so still an ignition problem. It will also some times stumble above 5k. When I first got the car, I rebuilt the carb as the fuel tank had rusted out and all the circuits in the carb had rust particles. I need to replace the two bottom condensers, as I didn't see them when I originally replaced the top two,

Took it out for a spin and was happy that it's not leaking, and when the secondaries open, that's a hoot. I can get it out the garage, which makes my wife happy.

Plenty of info on this and various sites about replacing the dizzy with an FB version. I did find this remanufactured, points dizzy at advanced auto parts Cardone Distributor {Point Type} for $120. What do you think of that?

 

Read my initial response to your thread,for $120 you could have the majority of what you need for an FB electronic ignition distributor upgrade.

If you need/must retain points ignition,look elsewhere for a reman distributor, Cardone products have a well deserved reputation for bottom of the barrel reman replacement parts.

 

Will skip the reman.
One of my concerns about switching to an FB dizzy is the igniters. I did read that there are GM versions you can use.
Thanks for the insights.

 

There are no particular concerns with igniters,have owned several FBs with well over 100k mikes with no trouble from igniters. Have seen a handful of them fail on customers cars,there are aftermarket igniters available that are reasonably priced I have used with no problems.

The GM igniters you reference are not a “bolt on”,they are often used in a direct fire ignition conversion used with 3 ignition coils. 1 for each leading spark plug for each rotor that go direct from coil to plug and the other that fires the trailing ignition traditionally thru cap/rotor.
The spark going straight to leading plugs has less resistance from not having to jump air gap between cap/rotor and each coil having its own igniter to charge and fire it means more usable spark energy makes it to the plug. Most modern cars have some type of direct fire system for better economy and reduced emissions.

Results are easier starts,especially if you somehow manage to flood engine. This modification enhances low end torque somewhat and allows engine to pull harder thru the rev range.

If you were to swap toFB dist/coils/plugs wired in original configuration,you’d certainly see easier starts,better performance and very likely the hiccups,tach bounce would be cured too.

Doing direct fire ignition conversion would further enhance these traits.
Do not know your skill level but quite a few here have done this conversion easily. There are a lot of threads here for the how to,read up and see which way you want to proceed.

For “original” ignition swap you’ll need: Distributor with igniters,two electronic ignition coils,some 16-14 gauge wire and a handful of 16-14 gauge crimp terminals.

Fir DFI:all the above + 1 more coil,enough spark plug wire to go from coils to both leading plugs and boots and terminals for both ends. 2 GM 4 pin modules used on any late 70s-early 80s GM car,they are cheap enough at any auto parts store. A mounting bracket fashioned from.a piece of aluminum for the modules to mount to as a heat sink to cool them and thermal paste to apply to back of module to assist in transfer of heat.
@ 6’ of 18 gauge wire to go from dist to module mounting area,some more crimp terminals and some time.
Post any questions you may have,all here happy to help.

 

Depends on your goals for the car. If a DD or more performance oriented swap to electronic ignition and dump points. Direct fire is event better and not that much more work. Keeping points work correctly means all the parts have to be working precisely, dizzy and advance, regulator and electrical connections.

Most points issues are related to regulators being dirty or bad followed by poorly functioning dizzys. Dizzys can have issues like rubbing block wear, points wear, powder from points gumming up mechanism and causing corrosion. Can be a challenge to keep on top of and you have to keep on top of them.

 

Regarding the GM igniters, I had read that original FB igniters were getting hard to come by, and cost a lot. I'm not really interested in the direct fire route, just eliminating the stumbles.
(Maybe more later. I'd enjoy it more if it just ran smoothly)

 

Then you need to either go through the points, dizzy, and regulator and make it all work or convert to electronic FB ignition. Don't use the 1980 dizzy, it sucks and the ignitors are not attached to the dizzy, so get an FB dizzy.

 

I had the exact same issue with my 79. Replaced the points distributor with a electronic ignition one smoothed out the idle tremendously, and solved the jumping tach/timing.

If the carrier plate in the dizzy is worn out, it’ll make the timing jump around. There isn’t a good supplier of points carrier plates, but there are ones (with new pickups) still available for the electronic dizzys.

Your idle issue is probably a vacuum leak. I had to do a lot of searching for mine, and it turned out to be the Air Control Valve for the air pump had an internal leak. Disabling it made the engine run perfectly.

 

While I haven't seen it done, I don't think there's any reason you couldn't do the stock FB system but with GM igniters - although at that point you might want to reconsider DFI. I used DR-100's sourced from AutoZone (about $20 a piece) for my DLIDFIS install, but I'd think you could use them on the stock setup as well. You'd still have to run new wires and find a place to mount them, not mention picking up some electronic ignition compatible coils and the FB dizzy, but it would be cheaper and perhaps even better performance-wise than sourcing J109's. Of course if the dizzy you get already has igniters I wouldn't mess with them; this would more so be an alternative to the problem of not having any in the first place. If you consider going this route let us know and I'm sure I or someone else could throw up a quick wiring sketch and of course answer more questions.

 

I've got the stumbles reduced, but am going to upgrade to an fb. I've picked up a set of coils, and have bought a fb dizzy off ebay. the seller says the ignitors are good.