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Engine starting/running problems

benbuilder

Well-Known Member
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2:57 AM
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Jan 3, 2012
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Location
Massachusetts
I have a 70 coronet. 383 4 speed. headers. I have owned the car for 13 years. Drive it in the summers. I took it out last week for a 50 mile ride. Perfect. Yesterday I started it in my garage and I started it and heard a big backfire. I restarted it, it ran rough for a bit and then it seemed fine.

I took it out of the garage and parked it. I started it again about an hour later and went out for ice cream. It stalled going down the road. I restarted it while coasting and heard another loud backfire. I am not sure if it stalled or not, but I coasted into a lot. It would not start so I had it towed home.

When I got home I put an inline spark plug tester to see if I was getting spark and it started rough. I took off the tester and restarted it but it ran rough.

This morning I started it as normal and it ran rough again then stalled. I tried to immediately restart it but it would not start.

Where should I start looking? There is no way the timing chain could have jumped is there?

Thanks
 
I'd look to see if a plug wire got burned first.
 
Anything is possible. Start with the easy stuff.
 
Distributor move on you? Cap ok? Wires ok? Not arcing across 2 wires or burn a couple?
 
If the carb is a holley, older than 1992, then the initial backfire may have ruptured the powervalve diaphragm. Then it would be dumping fuel through the port where it sees the manifold vacuum signal which would make it run rough and hard to start.

Or maybe its just something simple like a sunk/stuck float.
 
This is all absolutely dead-on good advice...... work on the spark & double check the power valve if a Holley
 
check the coil could be going bad seen this before if you have points check them also the only way the timing chain can jump if the cam gear has plastic teeth
 
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