Spark/ distributor trouble

[Daveyd]

Hey guys, I’ve been having a problem with backfiring, funky idle and the biggest is when I go to time it, I can’t get a light to work. I realized last time I tried to time it, if I pushed the vaccuum canister to the passenger side(clockwise) it sounded better and on all cylinders and not shaky or anything. Today I noticed it ran much better if I pressed on the driver side of the cap and the light would fire. Is this a worn rotor and cap or is it something wrong with the whole dizzy. Any help is much appreciated. Thanks in advance, driving around a military base and town with a backfiring bronco, while funny, could prove dangerous to my health haha.

 

[B RON CO]

Hi, it sounds like you may need to change all the tune up parts, cap, rotor, wires, points and condenser and spark plugs. If all those parts are old it is a good place to start. All the tune up parts wear out over time. You can inspect the condition of the cap for cracks and tracking inside, and you could run the engine at night and look for arcing wires. Good luck

 

[Daveyd]

Thanks for the reply. So I changed the plugs, wires, cap, rotor and points and still the same. Lumpy, shaky idle, sputtering and backfiring, yet when I push on the side of the cap the 1 cylinder comes out of, the shaky, lumpy idle flattens out. While I’m not a zip tie and duct tape guy, I’m tempted to just zip tie it to the heater 90 for now. My gas mileage is killing me. Any more help would be greatly appreciated.

 

[gr8scott]

Might look into converting to Duraspark.
https://duckduckgo.com/?sites=classicbroncos.com/forums&kz=On&k1=-1&kae=d&q=duraspark+upgrade&ia=web

 

[DirtDonk]

Is this still a points type distributor?
What about age? Is it original?
What is the state of the engine block as far as you can tell? In other words, do you think the bore that the distributor fits into could be more rusty than normal at this age? Or maybe have more oil than normal?

Reason I ask about those points is that, while it's not a common issue, the distributor could have a bad connection to the block.
Don't the old distributors also have a little braided ground strap between the points plate and the body of the distributor? I can't remember, but I know it's an important aspect of the Ignitor conversions.
Just can't remember if they were on all points-type units.

Good luck.

Paul

 

[Gordys74]

I had the same trouble with my stock distributor, it was worn and couldn't keep time and spark consistant. I replaced mine with a new one and all those troubles went away. You can rebuild distributors and that might be an option you would want to consider but I wanted something shiny.

 

[KeithKinPhx]

Just installed a new Pertronix billet distributor this week. Haven't fired it up yet since the engine is on a stand. Looked at the old one and decided that 50 years of service is enough. Had the old Pertonix 1 module in there for years and it did good so I figured I would invest in their distributor.
https://www.wildhorses4x4.com/product/Pertronix_Billet_Distributor/Bronco_Performance_Ignition

Opted for a red cap.

 

[blubuckaroo]

I wonder if the distributor's bushings are loose and affecting the point gap.
Pull the cap and rotor back off and give the distributor shaft a wiggle. You should be able to tell if it's loose.

 

[Skiddy]

I wonder if the distributor's bushings are loose and affecting the point gap.
Pull the cap and rotor back off and give the distributor shaft a wiggle. You should be able to tell if it's loose.

had that happen to me on a 289, if it wasn't for the tach acting weird
it would have been harder to diagnose

 

[blubuckaroo]

If you set your points with a dwell meter, worn distributor bushings will show up right away. The dwell meter won't be steady.