Need Help Pleae!!- Bad backfire and missing
Thread Starter
Instructor
Joined: Apr 2005
Posts: 200
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From: Finksburg Maryland
Need Help Pleae!!- Bad backfire and missing
I 've had this car for 10 years and its always ran perfect. I installed a different air cleaner, and I had to bend the bracket for the coil back on more of a slant to make it fit. Ever since I did that, the engine has run horrible. I get backfiring through the carb and mufflers, and a bad miss. I thought I may have cracked the distributor cap accidentally, so I changed the cap and rotor. It didn't help. I tried to check the dwell and timimg but I can't keep the engine running. Does anybody have any suggestions on where to start diagnosing this problem. Any help would be greatly appreciated.
Melting Slicks
Joined: Mar 2008
Posts: 2,336
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From: North Bellmore Ny
St. Jude Donor '09
Did you crack the housing for the coil? Check it out by removing it. If it has the smallest crack it will be a cause for stray voltage that never gets to you plugs causing an issue as you explained.
Racer
Joined: Apr 2008
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From: destin fl
Thread Starter
Instructor
Joined: Apr 2005
Posts: 200
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From: Finksburg Maryland
Well I visually inspected the coil and it looks ok. I wonder if I damaged it internally. I did bang on it with my hand to bend it back. I guess I'll pick up a new one, just to rule that out.
Thread Starter
Instructor
Joined: Apr 2005
Posts: 200
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From: Finksburg Maryland
I did doublecheck the firing order and that is right. The coil wire to the distributor cap did seem a little loose. I'll pick up a coil and some new wires tomorrow. Hope that does the trick. Thanks for the quick responses. I appreciate the help.
Instructor
Joined: Jan 2009
Posts: 100
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From: Dimondale Mich
If you have vac advance on the distributor, I'd check for a vac leak or a hose that may have come off or cracked. I had this happen on my van one time. Let me tell ya, it took an oval shape muffler and made it round from all the backfiring. 
Drifting
Joined: Feb 2005
Posts: 1,438
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From: Melrose Florida
My bet would be you shifted the distributor. You should be able to statically time it close...engine/ignition off, rotate to #1 TDC, (pencil or wooden dowel) in #1 hole, set to about one-half inch before TDC.
Steve
Unless you have points...if so, the dwell is way off (points gap), and it affects timing significantly. If so, install new points, gap with feeler gauge, set timing as described above, start car, set timing, set dwell, reset timing, check dwell -- drive car!
Steve
Unless you have points...if so, the dwell is way off (points gap), and it affects timing significantly. If so, install new points, gap with feeler gauge, set timing as described above, start car, set timing, set dwell, reset timing, check dwell -- drive car!
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Thread Starter
Instructor
Joined: Apr 2005
Posts: 200
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From: Finksburg Maryland
All this info is a great help. The aircleaner isn't touching anything. I just had to bend the bracket for the base to fit. I guess its possible that I could have cracked or knocked off a vacuum line. I know the distributor didn't shift. The hold down bolt is tight and I tried moving the distributor and its tight. The points could possibly be out of whack. I'm going to replace the coil and wires, and check the points and vacuum and if it still isn't running, I'll try the "in the dark" method. That will be a last resort since I'm trying not to blow the air cleaner or the mufflers off the car. One other thing I noticed was that I ran it for about 1 minute and when I shut it down, the header tubes from 1 2 3 and 4 were cold but 5 6 7 and 8 were hot. Not sure why. Thanks again for all the help.
Melting Slicks
Joined: Mar 2007
Posts: 2,520
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From: Hinckley OH
New Air Cleaner??? Are you sure the air cleaner isn't interfering with the operation of the choke or some of the linkage? Back in the day, I heard of people tightening the air cleaner too tight and deforming the top of the carb so that the choke wouldn't move.
Did the air cleaner knock off some vacuum hoses?
You said the header tubes 1, 2, 3, and 4 were cold. So the two front cylinders on each side of the engine don't seem to fire. Is that correct?
Did the air cleaner knock off some vacuum hoses?
You said the header tubes 1, 2, 3, and 4 were cold. So the two front cylinders on each side of the engine don't seem to fire. Is that correct?
Thread Starter
Instructor
Joined: Apr 2005
Posts: 200
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From: Finksburg Maryland
Yeah Apparently the front 2 cylinders on both sides aren't firing. Its not the choke. The choke has been stuck open since I got the car. This is much worse than just a cold engine with no choke. The air cleaner is not touching any part of the coil. I'll have to check the vacuum hoses. I'm not real good with the vacuum system. I don't have a diagram and I'm not real sure where everything is supposed to be. If a line came off, its not real obvious.
Melting Slicks
Joined: Mar 2007
Posts: 2,520
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From: Hinckley OH
I think it's time to go to basics. I would check for spark at each cylinder to see if they all SHOULD be firing. If you have a good spark at all 8 cylinders they you need to look at timing. Look at Steve's post. The points could have worked loose. That would throw timing way off.
I'm assuming you are getting gas because it is backfiring.
You didn't say if you did anything else when you put on the new air cleaner (specifically change plug wires) so the following is not likely to be the cause but you did change the distributor cap after the problem started so I'll throw out the thought.
The firing order could be correct but if the wires aren't attached to the correct posts on the distributor it won't work. You should make sure the rotor in the distributor is pointing to the #1 Spark plug terminal on the distributor when the timing mark is at zero. Keep in mind that the engine turns over twice for each revolution of the distributor so if the rotor isn't pointing to number one you should rotate the engine one turn and check again.
I'm assuming you are getting gas because it is backfiring.
You didn't say if you did anything else when you put on the new air cleaner (specifically change plug wires) so the following is not likely to be the cause but you did change the distributor cap after the problem started so I'll throw out the thought.
The firing order could be correct but if the wires aren't attached to the correct posts on the distributor it won't work. You should make sure the rotor in the distributor is pointing to the #1 Spark plug terminal on the distributor when the timing mark is at zero. Keep in mind that the engine turns over twice for each revolution of the distributor so if the rotor isn't pointing to number one you should rotate the engine one turn and check again.
Racer
Joined: Apr 2008
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From: destin fl
Yeah Apparently the front 2 cylinders on both sides aren't firing. Its not the choke. The choke has been stuck open since I got the car. This is much worse than just a cold engine with no choke. The air cleaner is not touching any part of the coil. I'll have to check the vacuum hoses. I'm not real good with the vacuum system. I don't have a diagram and I'm not real sure where everything is supposed to be. If a line came off, its not real obvious.
Team Owner
Joined: Jul 2008
Posts: 23,419
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From: In limbo
St. Jude Donor '13-'15, '17 thru '22
This may sound silly, but.....
If my car was running great for a decade, and then I changed my air cleaner and bent a bracket holding my coil to make room for this new air cleaner, and upon re-assembly my car had a major problem, I would be inclined to bend the bracket back and put the old air cleaner back on. Then, I would drive the car. One of two things will happen: the problem persists, or it disappears. Based on the outcome, I think my path would be clear. If I put the old equipment back on and the problem was still there, I would take a wild *** guess that I dorked something up while installing the new one (likely my coil or some connection to or from it) and chase the problem that way. If the problem disappears, I will have learned a very valuable lesson and will proceed much more cautiously on my next attempt to install the new air cleaner.
Good luck!
If my car was running great for a decade, and then I changed my air cleaner and bent a bracket holding my coil to make room for this new air cleaner, and upon re-assembly my car had a major problem, I would be inclined to bend the bracket back and put the old air cleaner back on. Then, I would drive the car. One of two things will happen: the problem persists, or it disappears. Based on the outcome, I think my path would be clear. If I put the old equipment back on and the problem was still there, I would take a wild *** guess that I dorked something up while installing the new one (likely my coil or some connection to or from it) and chase the problem that way. If the problem disappears, I will have learned a very valuable lesson and will proceed much more cautiously on my next attempt to install the new air cleaner.
Good luck!
Thread Starter
Instructor
Joined: Apr 2005
Posts: 200
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From: Finksburg Maryland
Well I've never claimed that I'm a genius when it comes to cars but it seems amazing to me that I could screw the whole thing up by changing the air cleaner. I wouldn't have even changed it but I read on some post on the forum that the aftermarket Edelbrock air cleaner I had was known to catch on fire. Once agian, an easy fix turns into other problems. I've learned my lesson. If it ain't broke, I ain't fixing it.