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Discussion Starter #1
Been working on my 69Z since bringing it back from the dead. Rebuilt carb, new gas tank, fuel pump, new plugs, flushed the fuel lines, new filters, new gas. Been running it every weekend for months, sometimes more. Today, go to start it up and she cranks but for some strange reason she doesn't catch. Then I get one hell of a backfire. Small amount of vapor/smoke comes out of drive side tail pipe for a minute or two after. Try to turn her over, nothing. Crank crank crank. Nothing. I try some gas in the carb, crank, she won't catch. Trying to figure out my next step here. Is it the coil? Timing out of whack? Points?
 

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Check for spark at the plugs. The backfire makes me think you do have fire to the plugs, but what about through the plugs. The plugs could be gas fouled.
 

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Mike
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I agree with X-77 keith. The first thing I would check for is a spark. Remove the coil wire from the distributor cap and check for spark when the engine is cranked... and then reconnect the coil wire into the distributor and check a couple of of the plug wires at the spark plug end.

If you have a spark, the next thing to check is the distributor to see if the hold down bolt/clamp is loose... try to turn the distributor cap. If the distributor is tight and does not move, remove to cap and inspect the mechanical advance for proper operation (both springs in place and weights not sticking).

If all that checks out, remove the coil wire from distributor and ground. Remove the air cleaner lid from the carburetor. Have someone crank the engine (or turn on electric fuel pump... if equipped) while you look down the throttle bores to see if gas is flooding in (be sure to wear safety goggles). If you see gas pouring into the carb, you might have some dirt stuck in the needle & seat... or your floats are too high.
 

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I agree with X-77 keith. The first thing I would check for is a spark. Remove the coil wire from the distributor cap and check for spark when the engine is cranked... and then reconnect the coil wire into the distributor and check a couple of of the plug wires at the spark plug end.

If you have a spark, the next thing to check is the distributor to see if the hold down bolt/clamp is loose... try to turn the distributor cap. If the distributor is tight and does not move, remove to cap and inspect the mechanical advance for proper operation (both springs in place and weights not sticking).

If all that checks out, remove the coil wire from distributor and ground. Remove the air cleaner lid from the carburetor. Have someone crank the engine (or turn on electric fuel pump... if equipped) while you look down the throttle bores to see if gas is flooding in (be sure to wear safety goggles). If you see gas pouring into the carb, you might have some dirt stuck in the needle & seat... or your floats are too high.
could be a broken timing chain
 

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Ouch, good point. Pop the cap and make sure the dizzy is turning.
 

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Mike
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could be a broken timing chain
Pop the cap and make sure the dizzy is turning.
Agreed... very good points.
Could also be from installing a bronze distributor gear on a ductile iron cam gear. The bronze gear will wear down in a very short time. This exact scenario happened to a friend of mine.
 

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Discussion Starter #7
Ok, I get spark from the coil. Let it sit for two days and tried again today. Engine caught once at the beginning, a bit of minor odor from exhaust which means there was spark and ignition although somewhat minor. Pulled a plug and yes, gas fouled. Will clean each of the plugs and give it another shot. As for the timing chain--not sure that applies given the firing. Thanks for all the advice, I'm working through em one by one.
 

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Mike
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As for the timing chain--not sure that applies given the firing. Thanks for all the advice, I'm working through em one by one.
If your engine is still using the cam sprocket with the nylon/plastic teeth, these teeth could be worn down causing the timing gear to jump. You will still get a spark at your plugs... but it will be firing at the wrong time.

Using the timing marks on your balancer and timing tab, bring your engine to TDC on #1 cylinder (be sure to remove spark plug from #1 and check for air pressure as timing mark on balancer approaches TDC).
Once your timing marks are lined up on #1 TDC, note the position of the #1 terminal on your distributor cap (I like to attach a piece from a wire shirt hanger to something in the engine bay and then point one end of the wire directly at the #1 terminal on the cap). Now, remove the distributor cap and note the position of the rotor. The metal tab on the rotor should be pointing at the #1 terminal on the distributor cap (or pointing directly at the end of the wire... if used as described above).
 

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That crap nylon timing chain killed my first car engine,71 Nova 307 that I started adding hot rod parts to at 15. bent a couple of valves too.
It needed a fresh 355 anyway. Hope that's not your issue $$$

Hopefully just a carb flooding or distributor issue.
 

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Discussion Starter #10
Thanks again. Just cleaned the plugs and tried to restart again. Got another gunshot out the left exhaust and some smoke. Will try RifRaf's suggestion tonight. Also, bought a Pertronix III Ignitor and new coil. May just put that in first before I monkey with distributor/points. As for the timing chain, it is the original from 69.
 

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I have never had any luck cleaning gas fouled plugs. Gas kills them. I would put fresh plugs in them. I had the same problem years ago when just pulling a car in and out of the shop to make room . It backfired. Pretty bad. New plugs fixed it every time. Just my recommendation.
 

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Brett - Leander, Texas 1969 SS396
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You mentioned points a couple of times. I think if your car still has points and it has been a while since it has started, you might be having an issue with the points. That would cause a spark issue.
Brett....
 

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Discussion Starter #15
So I do get spark from the coil. I cleaned the plugs--wouldn't catch. I replaced the plugs. Car turns over but nothing. Bret mentioned points, but I've ordered a Pertronix Ignitor III and a new coil (the one in it is over 30 years old) so I'll pass on buying new points til that comes in.
 

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The points could be working, giving spark, but so far out of correct dwell, they won't run the engine properly, could also be worn out upper distributor bushing, and no ignition system will fix that.

Also, just to be the spolier, and I am not trying to get you riled up, but, firing order correct on its rotation, clockwise from the top??? I've seen all sorts of people, amateur to full on great mechanics do this backwards, wire left, when it needs right rotation. Anything is possible.
 

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I once accidentally switched two plug wires when I was doing plugs and wires and had very similar symptoms.
 
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