ignition timing ?

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Tnplumber

Tnplumber

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I was having some ignition trouble with my Dart, bone stock '72 318 2bbl automatic with stock electronic ignition, and found that my distributor was worn, so I replaced it with a new stock replacement. When I put in the new distributor and started it, I noticed the engine semmed much stronger and idled great. A bog that had seemed to plague this car since I had it seemed to almost disappear. I took it for a run, it seemed much stronger on acceleration, but that spark knock. When I put a timing light on it, the mark on the damper was so far btdc that you couldn't see it. When I advanced to TDC the car seemed sluggish and when reved up would backfire out of the carb. So I retarded the timing and it smooth right out and about 20 degrees btdc but the blog was still there.

Some other notes: new plugs, wires, cap. rotor, ecu, coil, ballast, and distributor. The plugs look great, not rich or lean. Had the vacuum line plugged while timing the car and it was warmed up with the choke open all the way. 34k miles on untouched motor.

Any ideas?
 
So is the mark on your damper in the right place? If you have to run the mark way up under the water pump to get the engine to run decent something ain't right. Maybe the outer ring moved or you have a 273 damper.
 
C130 Chief said:
So is the mark on your damper in the right place? If you have to run the mark way up under the water pump to get the engine to run decent something ain't right. Maybe the outer ring moved or you have a 273 damper.
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That's what I was thinking. Still a mystery. The car runs great.
 
Tnplumber said:
According to my Chiltons and Motor's books from the 70s TDC.
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OK. Just checking. I had a 74 Fury with a 360 and it was spec'd at 8 btdc. There are other factors that determine what the factory set them at.

You can usually make it run better as you noticed by advancing them to the point right before they spark knock. Usually that's around 34-36 degrees total timing. I always advance them 2 degrees at a time and test drive it and listen for spark knock. When I hear spark knock I back the timing off about 3 degrees. Most will spark knock but a couple I've had you couldn't hear any so with them I just set them to 35-36 degrees total. Using this method I have found gives best power and fuel mileage and makes the engine more responsive.
 
fishy68 said:
OK. Just checking. I had a 74 Fury with a 360 and it was spec'd at 8 btdc. There are other factors that determine what the factory set them at.

You can usually make it run better as you noticed by advancing them to the point right before they spark knock. Usually that's around 34-36 degrees total timing. I always advance them 2 degrees at a time and test drive it and listen for spark knock. When I hear spark knock I back the timing off about 3 degrees. Most will spark knock but a couple I've had you couldn't hear any so with them I just set them to 35-36 degrees total. Using this method I have found gives best power and fuel mileage and makes the engine more responsive.
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All I can say is that it runs great, starts cold, never tries to stall, so I guess it could be worse. I don't hear any spark knock even in passing gear up a steep incline. It will actually run and not stall at tdc but will back fire occasionally out of the carb. As always Fishy, thanks for the help, I needed it.
 
Tnplumber said:
All I can say is that it runs great, starts cold, never tries to stall, so I guess it could be worse. I don't hear any spark knock even in passing gear up a steep incline. It will actually run and not stall at tdc but will back fire occasionally out of the carb. As always Fishy, thanks for the help, I needed it.
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If it runs that good don't mess with it. That's an old motto and a good one. The occasional backfire could be the carb. accelerator pump is a little lean.

Everybody have a good week
 
fishy68 said:
If it runs that good don't mess with it. That's an old motto and a good one. The occasional backfire could be the carb. accelerator pump is a little lean.

Everybody have a good week
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I meant it backfires occasionally out of the carb when I had it at tdc, I have it about 30 degrees btdc and it runs perfect. thanks again. I'm gonna drive it and just enjoy it, lol.
 
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