Ok, I think we're narrowing it down. Ran the worst it has today since the problem started. Even at low temps this morning, still had a mild stutter occasionally. On the way home, temps in the low 80s, ran badly, backfiring a couple of times, and had to baby it all the way home. Got home today and tried the one combination I had not tried yet. New cap and rotor, old plug wires. Noticeable improvement. Timing advanced 2 degrees immediately. Backed it off back to 5* and took it for a run. Didn't stutter through 1nd-2nd with mild acceleration, shifted into 3rd and all ok. Cruising at about 50mph, I kicked into passing gear and it started stuttering somewhat. Not too badly, but noticeable. I'm leaning toward an ignition problem. Won't be receiving new plug wires until later next week so I'll have to wait on them to see if it's licked. Thanks for all the help and advice!

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1974 Dodge Dart, 225cid, A904, Factory A/C, "Special Edition"

I had a similar problem on my duster and it ended up being the pump in the carb. I installed a hand choke and pulled it half closed and the problem went away. I got a rebuild kit and rebuilt the carb and it is doing fine.

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Jack

It's a reman carb, only about 6 months old. Been working excellent. It's run perfectly since the first day I put it on. I know things often happen with carbs though. Thanks for the tip!

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1974 Dodge Dart, 225cid, A904, Factory A/C, "Special Edition"

While I don't often 'throw parts' at a problem, it sounds like a simple weak spark situation and you improved the spark energy a bit with the changes in rotor and cap. That fits the symptoms of variable firing with varying engine load.

With the new wires, if it persists, I would be thinking about changing the coil. You can measure coil resistances and probably should do so if the specs are known, but that is not finally conclusive on a coil; internal shorts that you cannot easily measure can come and go and effect the spark voltage considerably. What coil is in there now?

The current coil is a STD/Bluestreak UC16, installed about 4 mos ago when I first switched to HEI. I ran a resistance test and it was within spec. Thanks!

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1974 Dodge Dart, 225cid, A904, Factory A/C, "Special Edition"

The resistance check is good but not conclusive. Intermittent internal shorts will not show up on a resistance test; and they sometimes get worse with heat. So, don't yet totally rule this out as the possible issue.

UC-16 isn't really meant for use with HEI. An FD-478 is a better pick, though you'll have to have a different coil-to-cap wire because FD-478 has a male (spark plug type) secondary terminal.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Got it! Thanks. I'm off Monday so I'm going to go ahead and replace the timing chain/gears and adjust the valves while I'm waiting on the plug wires.

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1974 Dodge Dart, 225cid, A904, Factory A/C, "Special Edition"

Really? The UC16 was one recommended in the HEI write up in the FAQs under the electrical forum. Granted it said "at the very least ..." but I took it as being acceptable since I'm using the Std/Bluestreak LX301 4 prong module instead of the HEI coil combined setup. After I get my new plug wires I'll look into the FD478 and matching coil wire. Thanks for the tip!

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1974 Dodge Dart, 225cid, A904, Factory A/C, "Special Edition"

Double post again! I swear I'm only hitting submit once. Must be this darn phone.

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1974 Dodge Dart, 225cid, A904, Factory A/C, "Special Edition"

Tapatalk?

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

No, just using the phone's browser to view the site.

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1974 Dodge Dart, 225cid, A904, Factory A/C, "Special Edition"

Plug wires fixed it! Got my new Aurora wires in and installed them this afternoon. Took her for a run on a backwoods highway and opened her up. Ran like a champ with no hesitation or stuttering at all. Thanks to everyone for all the help and advice!

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1974 Dodge Dart, 225cid, A904, Factory A/C, "Special Edition"

And there was much rejoicing!


(might want to post your fix results here, too for those who go searching in the future)

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I just took care of that, Dan. And thanks for leading me to the Aurora wires. They were very well made and installed with a nice little click at both the plug and the cap, so you know they're seated well.

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1974 Dodge Dart, 225cid, A904, Factory A/C, "Special Edition"