occasional Backfire!!!!
Thread Starter
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Senior User
Joined: Mar 2002
Posts: 200
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From: Columbus USA
occasional Backfire!!!!
Now that I have my points set correctly and my truck runs now... I still get an occasional backfire through the exhaust.....When the points weren't set correctly it blew my muffler in half.
What adjustment or check measure needs to be made..
Thank in Advance
What adjustment or check measure needs to be made..
Thank in Advance
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
occasional Backfire!!!!
Ray:
Hm, could be quite a few things. Have you checked the dwell yet - the feeler gauge method gets you in the ballpark you'll want to be at 26 to 29 right in there - Did you install new points - and a new condensor?
Also, check for a cracked distributor cap, and check your wires -- if two adjacent wires run parallel with each other for a bit one can induce a voltage into the other, firing at the wrong time, causing backfire. Wires should 'cross' each other to prevent this.
Make sure your firing order is correct -- that is, the right wire is going to the right cylinder. You can swap a couple around and most people wouldn't even notice!
Keep 'er between the ditches.
Hm, could be quite a few things. Have you checked the dwell yet - the feeler gauge method gets you in the ballpark you'll want to be at 26 to 29 right in there - Did you install new points - and a new condensor?
Also, check for a cracked distributor cap, and check your wires -- if two adjacent wires run parallel with each other for a bit one can induce a voltage into the other, firing at the wrong time, causing backfire. Wires should 'cross' each other to prevent this.
Make sure your firing order is correct -- that is, the right wire is going to the right cylinder. You can swap a couple around and most people wouldn't even notice!
Keep 'er between the ditches.
Thread Starter
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Senior User
Joined: Mar 2002
Posts: 200
Likes: 0
From: Columbus USA
occasional Backfire!!!!
ok Professor Ted:
I installed my wires a short while ago, I could have a wire on a wrong cylinder...What's the numbering order on the cap...is there a wa that you can tell?
I installed my wires a short while ago, I could have a wire on a wrong cylinder...What's the numbering order on the cap...is there a wa that you can tell?
Thread Starter
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Senior User
Joined: Mar 2002
Posts: 200
Likes: 0
From: Columbus USA
occasional Backfire!!!!
Could you give me some good step by step instructions for setting the dwell?
Never done this old time ignition stuff, should probably run petronix but want to stay original...
Never done this old time ignition stuff, should probably run petronix but want to stay original...
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
occasional Backfire!!!!
The Y-Block is a bit different then later V8's.. this may be your problem. The firing order is 1 5 4 8 6 3 7 2, in that order, counter-clockwise on the dist. cap.
Keep 'er between the ditches.
Keep 'er between the ditches.
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
occasional Backfire!!!!
OK. Ray, you're not afraid to tear into something which is good, but you've got to take the time to do it right the first time -- it wastes time and is hard on the equipment.
You're standing in front of your truck, hood open. What a beautiful, clean engine! The left side (where the battery lives) starting from the front of the engine is the #1, 2, 3, and 4 cylinders, the right side starting from the front is #5, 6, 7, and 8 cylinders.
The crankshaft turns clockwise, the distributor anti-clockwise. The firing order is 1,5,4,8,6,3,7,2 - different than later Ford's!!! So, the first distributor cap wire in firing order will be the #1 (look on top of the cap) wire and will go all the way to the front 'left' of the engine. Keep going through, you'll know when you are done when there aren't any more wires.
Keep 'er between the ditches.
You're standing in front of your truck, hood open. What a beautiful, clean engine! The left side (where the battery lives) starting from the front of the engine is the #1, 2, 3, and 4 cylinders, the right side starting from the front is #5, 6, 7, and 8 cylinders.
The crankshaft turns clockwise, the distributor anti-clockwise. The firing order is 1,5,4,8,6,3,7,2 - different than later Ford's!!! So, the first distributor cap wire in firing order will be the #1 (look on top of the cap) wire and will go all the way to the front 'left' of the engine. Keep going through, you'll know when you are done when there aren't any more wires.
Keep 'er between the ditches.
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Laughing Gas
Joined: Oct 2001
Posts: 957
Likes: 3
From: Winchendon MA
occasional Backfire!!!!
Ray.
Re check your gap. The little rubbing block has to wear in to the dirib and it takes about an hour of running or so. I've had points close up .004 in just a few minutues of running and causeing back fires. Re-gap and double check the timming. The timming should not move much if you re-gap to the same gap.
44Dwarf
Re check your gap. The little rubbing block has to wear in to the dirib and it takes about an hour of running or so. I've had points close up .004 in just a few minutues of running and causeing back fires. Re-gap and double check the timming. The timming should not move much if you re-gap to the same gap.
44Dwarf
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Postmaster
Joined: Apr 2002
Posts: 3,613
Likes: 6
From: Coal country
occasional Backfire!!!!
Dwell: It is the amount of time, measured in degrees of rotation (out of a 360 circle) of the distributor shaft, that the points "dwell" together - remain closed, that is. A minimum dwell is necessary to make a strong 12V circuit inside the coil, which builds a strong magnetic field (just like an electromagnet), which, when it collapses, generates a strong spark in the secondary ignition circuit. Too little dwell means weak or no spark because the magnetic field isn't strong enough, and too much dwell, when the points stay together too long, doesn't break the circuit long enough to allow the magnetic field to collapse.
Ray, setting the points gap sets an INITIAL dwell. You use a dwell meter to get the final and best dwell. If you have a "conflict" between a measured gap and dwell, go with the dwell.
If you use steel (instead of brass or stainless steel) feeler gauges, you may be getting an inaccurate reading - hence an incorrect dwell, and possible backfiring.
Try setting the correct dwell with a dwell meter, and ensure you have a good capacitor, clean points, and good cap and rotor.
Ray, setting the points gap sets an INITIAL dwell. You use a dwell meter to get the final and best dwell. If you have a "conflict" between a measured gap and dwell, go with the dwell.
If you use steel (instead of brass or stainless steel) feeler gauges, you may be getting an inaccurate reading - hence an incorrect dwell, and possible backfiring.
Try setting the correct dwell with a dwell meter, and ensure you have a good capacitor, clean points, and good cap and rotor.
Logistics Pro
Joined: Feb 2000
Posts: 3,565
Likes: 9
From: Sun River St. George
occasional Backfire!!!!
Ray, Replace the damaged muffler and I think the noise you are hearing (backfire) will cease. As soon as you can install a pertronix Ignitor and forget about points forever.
William in Atlanta.
William in Atlanta.
