Backfire:carb...
Thread Starter
Drifting
Joined: Mar 2001
Posts: 1,896
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Backfire:carb...
I've been trying to get the 73 running all day. I took the MSD cap off my Vette, and the MSD Superconductors. It's got new spark plugs. All I get is back fires threw the carb and it runs real rough. Do i need to advace or retard? Which way is which??
thanks
Aaron
thanks
Aaron
Safety Car
Joined: Aug 2000
Posts: 3,909
Likes: 26
From: Clymer PA
Re: Backfire:carb... (Aaron-74)
Aaron:
It sounds like your engine is too far retarded (no I'm not trying to insult your engine :D). For the record:
Advance = Counter-Clockwise
Retard = Clockwise
It sounds like your engine is too far retarded (no I'm not trying to insult your engine :D). For the record:
Advance = Counter-Clockwise
Retard = Clockwise
Thread Starter
Drifting
Joined: Mar 2001
Posts: 1,896
Likes: 0
Re: Backfire:carb... (bence13_33)
I've got a Holley on my Vette. The 73 has a Q-jet. I think it would gain more from an Edelbrock or Holley. But oh well. We've checked, re-checked and checked the wiring order. I think It's just a timing thing. :yesnod:
Well, then I advanced it as far as I could, and It still did it....hmm... :confused:
[Modified by Aaron-74, 7:49 PM 6/25/2002]
Well, then I advanced it as far as I could, and It still did it....hmm... :confused:
[Modified by Aaron-74, 7:49 PM 6/25/2002]
Safety Car
Joined: Aug 2000
Posts: 3,909
Likes: 26
From: Clymer PA
Re: Backfire:carb... (Aaron-74)
Aaron:
Backfiring through the carburetor can also be improperly adjusted valves. If your valve lash is set too tight, what you are experiencing will happen. Come to think of it, too far advanced will cause the problem you are experiencing. If you are too far advanced, you will be igniting your mixture while your intake valve is still open (thus the backfire through the carb). The easiest way would be to hook a timing light up and set your timing that way.
Backfiring through the carburetor can also be improperly adjusted valves. If your valve lash is set too tight, what you are experiencing will happen. Come to think of it, too far advanced will cause the problem you are experiencing. If you are too far advanced, you will be igniting your mixture while your intake valve is still open (thus the backfire through the carb). The easiest way would be to hook a timing light up and set your timing that way.
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Drifting
Joined: Jan 2002
Posts: 1,645
Likes: 11
From: Schaumburg IL
Re: Backfire:carb... (Aaron-74)
Is this the first time after mods or after a major tune?
Either way backfiring is either timing off (dist. inserted and not on TDC of #1), crossed wires, or valves too tight.
Crank your engine over until #1 is on TDC on the timing marks as you are feeling for compression. Take a look where the rotor is pointing. #1 on the towers is straight out. Maybe a couple of teeth off?? Once you get TDC the dist. should be right on the money with the rotor on #1 terminal. Advance CCW a small amount and that should be plenty to start. This is the place to start from.
Either way backfiring is either timing off (dist. inserted and not on TDC of #1), crossed wires, or valves too tight.
Crank your engine over until #1 is on TDC on the timing marks as you are feeling for compression. Take a look where the rotor is pointing. #1 on the towers is straight out. Maybe a couple of teeth off?? Once you get TDC the dist. should be right on the money with the rotor on #1 terminal. Advance CCW a small amount and that should be plenty to start. This is the place to start from.
Thread Starter
Drifting
Joined: Mar 2001
Posts: 1,896
Likes: 0
Re: (Fevre)
The motor was running two hours before. Nice and strong. The valves are okay. The rotor on TDC is right below the #1 tower. I think it's just a timing issue, but I'm not dealing with it anymore, my dad took over.
Burning Brakes
Joined: Aug 1999
Posts: 774
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From: Palatine IL
Re: Backfire:carb... (Aaron-74)
It could be the Accel coil. I had one of those flake out on me and cause a major backfire through the carb that bent the Q-jet throttle plates! :mad It happened when the coil got hot. I will never use one again!!!
