Exhaust Manifold "SPARKING"

[R.White]

I have noticed that there are sparks shooting intermittently from the exhaust manifold. The sparks are between 2" and 4" in length and are not coming from the connection with the block but at random from the casting itself. This phenomenon is only seen when the engine is revved hard.

Is this "static" or could the casting be "porous"?

Has anyone come across this before?

Ray.

[TexasJohn55]

I have not, but it is sure to stir interest. Have you stuck your finger down there to intercept the spark? That is a long spark! Stick your finger down there, it it knocks the daylight of you, I would guess coil spark seeking a ground. If the battery ground cable is on the engine, I dunno. Either way, try a light weight ground wire from engine to whatever it is sparking to. I am going to watch this thread for sure. TexasJohn

[Guest DodgeKCL]

I doubt the manifold is that porous. It sounds like poor grounding. Are the 'sparks' yellow or blue? Do you actually mean electrical arcing or hot sparks from the engine combustion?

[R.White]

I don't understand it either. The sparks are more white than yellow or blue. At first I thought there must be an HT lead shorting out but on closer inspection it is definitely coming from the manifold casting. There is no way of knowing where on the manifold the spark will show up because they are completely random but if you think of what you get from an angle grinder but just one spark at a time you get an idea. To me it looks like a heat spark rather than an electrical short or arc and as there is no sign of a mis-fire, I would not be convinced that there is a grounding issue. The manifold has been repaired by brazing in the past but there is no sign of smoke. I can't feel any leaks like you would around a gasket for example.

As I mentioned before, I suggested it could be porosity or is "static" build up a possibility? but that would be a blue spark wouldn't it?

Ray.

[Machinist_Bill]

Almost sounds like your distributor is too far advanced in high RPM's and might be running a bit "Hot". Try retarding the distributor a bit and see if the sparking quits.

[MikeC5]

I have never observed anything like that before... I would think with a large spark like that it would cause a misfire were it inapropriate grounding. Static electricity is more prone in dry climates. Has it been especially dry? Any folks int he (U.S.) southwest seen anything like that?

[Machinist_Bill]

It's kinda damp where he lives Mike......

[1936 D2]

My feeling is if it would be that "porous" that you would see signs of smudging from soot or carbon. Those gas molecules are small enough that if they did find a way through the casting (improbable) that there would be a lasting sign like a soot smudge or such.

I am wondering more if you have had the manifold painted? If this is the case some of those high heat paints actually have metal particles in them. If the temperature of the manifold is reaching the limits of the cured paint, it may be "off gassing" some of the make-up of the paint or possibly even some of the metallic particles in the paint. This may all be a sort of a break down of the paint's chemistry from getting over its maximum temperature rating.

The white looking spark could be from aluminium. That is the metal used in the firework called "sparklers". When burning those look like they have white sparks.

Just a logical guess.

Edited May 25, 2013 by 1936 D2 (see edit history)

[Pete K.]

Ray, This has to be either one or more of your high tension leads leaking past the manifold wire clamp, where they are very close to the iron itself, then jumping to ground. At a high or higher RPM, one can not always tell when one cylinder's plug becomes grounded. There was also a 1920's tech note I remember reading about a Dodge engine grounding problem between the distributor housing and mounting flange. It was noted to mechanics to run a separate wire for a better ground at that point. I don't believe things there were changed in '26, even though they went over to 6 volts and other generator changes. I must agree with post #2 & #3. Last resort, call an exorcist.

[MikeC5]

Ha ha! Well Bill with this global warming and all you just can't be too sure...

[R.White]

O.K. well I have had another look at it and now it looks more like the sparks are coming from the area where there have been repairs and possibly from the underside of the manifold (where I can't see) so it could be from a gasket area. There is no paint on the metal; just rust which I have cleaned up with a wire brush. Earlier, I thought I had solved the mystery. I thought it could have been filings from where I have relieved the welds which had restricted the correct size bolts from being used to fit the exhaust pipe. I imagined that they were getting hot and being blown off the manifold by the draught from the fan..... that was until a few minutes ago when I noticed a spark arking from the advance/retard rod which goes from the bottom of the steering column (where it's sparking) to the body of the distributor. I'ts like a fireworks display under my hood!! (bit of an exaggeration!)

I am now more inclined to think in terms of grounding/shorting out problems but I don't know quite where to start. The back firing in the tail pipe problem has returned but now it starts after a mile and a half rather than 1/4 mile as it did before I replaced the coil. I thought I had solved that problem by setting the tappets with slightly greater clearances but that was, it seems, just wishful thinking. I am not happy that the valve springs have sufficient tension and may need to be replaced. Tomorrow I will ground the distributor and replace the high tension leads. I have grounded the transmission to the battery and as I may have mentioned replaced the 12 volt cables with the right 6 volt ones.

Today I made sure the carb was set up right in case the mixture was too rich as I have noticed that there is a tendency for backfiring to worsen with a richer mixture.

Ray.

[MikeC5]

There's your problem Ray, the steering column should be on the other side... Sorry, I couldn't resist... What about the pulg wires? Gap on the plugs? Big arcs like that can only come from the coil secondary. How do your cap and rotor look?

[R.White]

Sure thing, Mike... I shall have to put the steering column on the other side...that should sort it!

The dist. cap and rotor are fine but the plug wires are next on my list. There is no sign of shorting from them but they are a horrible red color so that must be the problem!!

Ray

[R.White]

Today I ran a grounding wire from the distributor body and that has stopped all the sparking. My thanks to all you guys with helpful suggestions. Thanks especially to Pete for the heads up on the distributor grounding problem.

Ray.

[TexasJohn55]

Hoorah! Another successful thread. TJ55

[Pete K.]

Glad to hear of your success Ray! Did the back firing cease too? ---Pete.

[R.White]

Hi Pete. When I grounded the distributor, the sparking problem stopped and I was hopeful that the backfiring problem would also go away but when I took the car out for a test drive I was beginning to pick up speed on the main road when the loud backfiring through the tailpipe started again; coupled with a corresponding drop off in power. I was not amused.

[TexasJohn55]

Mr. White, Seems to me if it was originally sparking to body part from the manifold, it was seeking ground. I still think you need to ground the engine to body and frame. If the engine is not grounded, will it not weaken the spark? All energy has to return to the neg battery post. If it were grounded good, would it have sparked from the manifold to start with? TJ55

[R.White]

Done that John; the engine is grounded to the battery. It is positive ground.

The problem now is the backfire through the tailpipe with a corresponding drop off of power.

In an attempt to solve the problem (and improve starting), I replaced the battery cables with heavy duty 6 volt cables and soldered on the terminals. I am running a new coil and condenser and the points are correctly gapped and not corroded and are not sticking. There is no sign in the dark of arcing in the cap and there are no signs of any hairline cracks. The rotor arm is in good condition and the contacts in the cap are not worn badly or corroded - but I have a new cap, rotor arm, HT wires and spark plugs on order. With new brass spade connectors soldered on I am hoping for some improvement. I would have checked out the HT wires but my timing light only seems to work on 12 volts!

It is possible that the advance/retard springs in the distributor have stretched and need replacing - could this cause a backfire? I have set the timing in accordance with the workshop manual; with No 1 (nearest rad) on TDC on compression stroke and timing mark c/14 in window in the flywheel housing. I have sufficient tappet clearances to ensure the exhaust valves are not sticking open when the engine is hot.

The only thought is that some fuel is being drawn down the vacuum pipe from the tank but I checked the valves before replacing the electric petrol pump with the restored vac tank. There is not a lot of black smoke as one would expect from a very rich mixture; I even removed the carb and reset it (as per instructions) to ensure the correct mixture. Perhaps tomorrow I will check out my cylinder compressions and by pass the ignition switch.

Ray.

Edited May 29, 2013 by R.White (see edit history)

[ply33]

. . . I would have checked out the HT wires but my timing light only seems to work on 12 volts! . . .

The 12v power source does not need to be the 6v car you are checking the timing on. You can clip the power leads of your timing light to a 12v battery and the sensor lead to your #1 plug wire. . . I've done this any number of times.

[Machinist_Bill]

Ray if you didn't have bad luck you wouldn't have any at all! Does it idle ok? Only happens when you give it gas? Let's round up the usual suspects:

1) Is the distributor advancing with the linkage?

2) Critters in the muffler?

3) Electrical short that comes and goes (Weak Coil) - No different than turning your key on & off to make the car backfire.

I know this is frustrating and sometimes you have to walk away. It's late where you are and tomorrow is another day.......

[TexasJohn55]

Mr White, Looks like you have the bases covered on the ignition plan. A 12v dry cell lantern battery will work, or 2 6v wired together for portability. If it is ignition misfire, the only way I can think of finding it under load it to hookup your timing light to one plug wire at a time and drive it with the light strobing. Then go to the coil wire and try it. You could pin it down to one cylinder or all if coil is shutting down. You can also check your plug wires with an ohm meter, they have a specified resistance per foot in length. A bad wire will be "open" but may still jump spark most of the time. TexasJohn

[R.White]

Sorry, but my keyboard spacer bar has stopped working! Ply33 thanks for that nice bit of lateral thinking. I will give it a go! The strange thing is that there is no noticeable misfire as you would expect under load but these low compression engines don't take much of a spark to run and so I guess there could be a voltage leak somewhere like the ignition switch ====Bill, the linkage is O.K. and I have movement at the distributor. What I don't know is how well the automatic advance/retard is working which according to the manual is responsible for 25 degrees (manual 20 degrees) of the total 45 degrees. If the springs are tired or broken this will cause the automatic advance weights to remain in the advanced position). I believe this will cause a backfire. I will need to check it out. I have had this before with a car but it did not backfire; just lacked power and overheated. The exhaust is clear. I have had it off completely for repairs and I am sure a backfire would have ejected any critters nest an all! John, the ohm meter idea sounds a bit advanced for me I am not sure how to test for resistance in plug leads I will be replacing them as soon as the new ones arrive. I could make up new ones from a coil of black HT wire but I might as well use the authentic looking ones coming from Myers and fit new plugs at the same time..... This is all still work in progress but I am in a busy with work lately. Thanks for all your suggestions and I will report on progress. Ray.

[Guest occrj]

If it's any comfort Ray, mine still doesn't run right either. I took the breaker assembly off the mag and noticed that the points had closed up. I cleaned them up and reset them correctly but it made no difference, I took it down the road just now and it still randomly misfires and the problem feels electrical still, although it runs marginally better once it's in top gear than accelerating through 1 and 2. Next is to make new HT leads I think, and if that doesn't work get the mag re-furbished. Might just be done in time for winter - not saying which year though!!

RJ

[R.White]

It can be frustrating when you think you have found the solution only to find out you haven't after all. For what it's worth Richard, you have my sympathies; not least because you bought the car in good faith. I knew that my car was going to be a challenge from the start. It would appear to have been assembled from a heap of non working parts - perhaps it was intended to be a museum exhibit or something; I don't know. The only thing you can do is eliminate one potential fault after another until eventually you arrive at a solution. Ray.

[Pete K.]

I don't have a magneto on my cars here, so I have to ask, do you folks that have a mag, do you also have a choice with the dash switch, like the Ford T, to switch it to battery ignition only? Does the problem subside then? Ray, I remember the mags have a tiny drill mark in the large gear to mate with the small driven gear so the MAG is timed right... Is that OK?

[Guest occrj]

Pete, yes there are marks on the larger of the two gears in the mag used for timing, I'm not aware of a switch to run from the battery only though. I think the timing is broadly correct, the car starts on the first turn of the starter, but under way is when the gremlins emerge. Anyway, back to Ray's thread RJ.

[R.White]

The one thing which worries me is the distributor. I have stopped the sparking by grounding it with a neatly connected wire from one of the two screws that hold down the points base; the wire then passes through a small hole in the side and the other end grounded at the coil bracket. The obvious fault is that the distributor is a loose fit in the gear housing; a casting which is part of the water pump. This should not be confused with lateral movement of the rotor shaft in relation to the contact breaker points, which in my opinion is not too bad - although I have to admit there is a bit of movement, but no worse than I have had before with other engines with no trouble. There is also a certain amount of backlash which is made worse by wear in the long linkage of the manual (hand operated) advance/retard mechanism. The drive gear is pinned to the water pump shaft by a half moon key which was in such a poor state I had to braze it in place. This greatly improved the backlash but the water pump shaft really needs replacing but until a restorable water pump core becomes available, I am reluctant to throw a lot of money at my present (poor condition) pump. The frustrating part about this is that having at last got the water pump working - and to stop leaking, I will need to strip it all down again to re bush the distributor but if it eliminates the tail pipe backfire, it will be worth the hassle. Before I touch the distributor, I will fit the new spark plugs and leads, distributor cap and rotor etc. to eliminate the simple things. Ray.

[Guest bull]

Well done Pete, like the look of your tourer on your "thumbnail". cheers

[Guest DodgeKCL]

I don't think the spark plug leads on that car are carbon filled. It's too early. I think all those old leads are steel cored and would read 0 ohms with an ohmmeter. But a break won't usually give any real problem as some spark plugs,to get a hotter spark, had a gap built into them to make the voltage build up to a higher value before finally being able to cause a spark. Both the internal gap,much smaller than the regular gap, and the regular gap sparked together. Unfortunetly it's very difficult to tell ignition faults from fuel faults in these old carburated cars. I would try pulling on the choke bit by bit when it starts acting up and see if that cures it. If it does it could be the high speed jet plugged. If you have a spare carb I would try that. If this doesn't fix things then I suspect it is timing. As Ply33 says you can power up your timing light with an external 12 volt battery and watch for the correct advance at high speed with just the throttle opened up in your garage. If the timing moves up but starts to 'walk' back and forth at high revs then this could cause the backfiring. It's doubtful the advance weigths would flop back and forth because of being held by centrifigal force. They either go out and stay out or they don't. The springs are calibrated for tension to control the 'ramp' or 'curve' under which the timing advances but I don't think they would jump around. At least not in my experience. I've actually opened up a distributor for maintenance and found one of the springs unattached and floating around in the bottom of the distributor. It had made no difference that I could tell to the running of the engine. But then the car is not run above about 50 miles an hour and sedately accelerated at that. It could be high voltage break down as damp leads and distributor on a rainy day will cause this same condition until things dry out. You want to try that old trick of waiting until dark and revving up the engine while you and some helper look around the engine for arcing. It sounds like you may not yet have found all the areas that need to be bonded/strapped to ground. Hope some of this helps but I'd still be scratching my head and I've been around engines for over half a century now.

Edited June 2, 2013 by DodgeKCL (see edit history)

[R.White]

Thank you Dodge KCL, for taking time to think outside the box for me. I had not heard about the 'helper' gap in a spark plug before. You are right that the leads are not carbon filled; but neither are they steel. In fact they are copper cored. The king lead, however, is different and is steel cored. I have run my 1930 Austin for 25 years on it's steel cored leads with no trouble whatever. I have new leads and spark plugs on order but could this solve the problem? Close examination of the distributor cap has revealed a small chip and what looks like a small hole drilled through but no sign of a hairline crack. There might have been trouble in this area before so the cap will be replaced as a matter of course. I have had the engine running in very dark conditions and there is no sign of arcing from anything so I don't know what else to ground. The distributor advance/retard springs are mentioned in my mechanics instruction manual as being a potential problem so maybe a long shot?............ Previously, I have taken the carb apart because I was convinced the piston must be sticking but every thing is operating as it should. I could try running the car on my spare carb so as to eliminate that possibility. There is just the one jet for all operating conditions in the Stewart Warner carb and it is clear. The timing issue is indeed something to check out. There is no data to help set up the timing with a strobe but I take your point about the impression of a mark "walking" as this is quite a common indicator but I don't understand what it conclusion it will lead me to. I have had two full time mechanic friends/customers of mine look at the car. One is leaning more towards fuel because he has never seen a vacuum tank system and although he understands the principle he is unhappy with it and suggests I rig up the previously fitted electric petrol pump so as to rule it out; if nothing else! The other guy is more than a little unhappy with the distributor and points set up and partly because of the wear suggests fitting an electronic ignition system. It's funny how guys who could fix my Range Rover with all it's computers in a jiffy are completely thrown off course by something as basic as a 1920's Dodge Brothers! Both suggestions may have merit, though, because I have tried all the obviously easy fixes and I still need to diagnose if the problem is fuel or electrics! Just to muddy the waters, when I first checked out the valve clearances I was alarmed to find that there was none! How long it had been like this I don't know but if the engine had been running in that condition for a while, it is possible that there is some burning of the exhaust valves. My next job (when I get time) will be to do a compression test. It feels O.K on the crank and so I think damage is unlikely but it would be a reason for unburned fuel getting into the exhaust and backfiring with a drop off in power. Ray.

[TKelly]

Ray, are you sure you have not leaned off the mixture too much? In my experience a lean mixture will cause a backfire not a rich mixture, a rich mixture will usually cause the engine to blow black smoke.

Regards, Tristan.

[R.White]

Thanks for your input. Tristan. I first experienced the tailpipe backfire when the mixture was far too rich and indeed there was black smoke blowing out. I assumed that too much unburned fuel would also backfire but a break in the ignition cycle can do the same. I have gradually weakened the mixture , the black smoke has gone and the engine no longer 'hunts' but the backfire problem persists and is accompanied by a fall off in power. I agree with you that a weak mixture can also cause a backfire - which is a point that Jack M made. I guess if the mixture is too weak to fire properly unburned vapour can backfire in the exhaust but the carb is now set up from scratch according to the Stewart Warner and Dodge Brothers manuals - if I remember, they both say to have the air valve just beginning to lift off it's seat then back off the needle by 1/16" then set the adjustment screw to half way for the choke anvil fine adjustment, making sure the choke cable does not disturb the setting - so I think the mixture setting is now about right. I hope! Until I get the car on a co. analyser I can't be sure. Remember, The car was a non runner when I got I it and there was one heck of a lot wrong with it. Ray.

Edited June 3, 2013 by R.White (see edit history)

[Guest DodgeKCL]

I set my air bleed screws with a vaccum gauge. This is the best and truest way as it calibrates the bleeding to your engine. The instructions in the manuals are for a brand new engine with no wear. And even then no two engines are exactly the same even at birth. I pull off the rubber tube for the vaccum wiper motor and hook up my gauge there. Then,with the engine running at a high idle,I turn the air bleed screw for the highest vacuum. Usually around 15 psi. It should be steady but it can move a bit on an older engine that needs the valves and seats cleaned up. No worries though. However if the needle jumps around a lot and you can hear a 'miss' in the engine at the same moment then it's usually time for a valve 'job' but it could also mean the ignition misfiring. Fun ain't it?

[TexasJohn55]

Mr White, Looks like you have the bases covered on the ignition plan. A 12v dry cell lantern battery will work, or 2 6v wired together for portability. If it is ignition misfire, the only way I can think of finding it under load it to hookup your timing light to one plug wire at a time and drive it with the light strobing. Then go to the coil wire and try it. You could pin it down to one cylinder or all if coil is shutting down. You can also check your plug wires with an ohm meter, they have a specified resistance per foot in length. A bad wire will be "open" but may still jump spark most of the time. TexasJohn

................Respectfully re-submitted for consideration. I thought you would have all your ignition wires and cap on by now..TexasJohn

[R.White]

Thank you KLC I will try what you suggest with my vacuum gauge...a much under rated instrument in my opinion - especially on older engines.

Yes Texas John, but I am awaiting a delivery from Myers ; it takes a while to cross the pond.

No excuses, but this is a busy time for me running the cattery so not enough hours in the day!

Ray.

P.S. I have just been to the car and have to admit that I had forgotten that there is no vacuum wiper or connector on my car - it has been converted to electric. There is only the straight coupling which I installed for the vacuum tank. I would need a 'T' connector and blanking plug which I don't have.

Ray.

Edited June 3, 2013 by R.White (see edit history)

[R.White]

This afternoon I checked the compressions. All four pots are the same at 50 p.s.i. (or as close as makes no difference). The valve clearances are 0.010 & 0.012 cold. enough I would have thought to avoid problems when hot but I will check again with a hot engine.

A tip for anyone who, like me, does not possess a 7/8" adaptor for their compression tester (these big plugs are not common over here). Remove the insulator from an old spark plug and press the 18 mm adaptor into the threaded section of the plug and you have a useful addition to your tool kit!

The spark plugs at present are 3/4" reach Champion W14. in good (now clean) condition.

Ray.

Edited June 3, 2013 by R.White (see edit history)

[Guest DodgeKCL]

Most of us don't use screw in compression testers over here. Our compression testers have a rubber 'bumper' on their ends which you just jam down on the spark plug hole and crank the engine. The inlet to the rubber piece has a Shraeder tire valve in it to hold the compressed air. After looking at it,you just tap the tip of the tire valve on the head somewhere and that lets out the compessed air. You just move to the next hole and Robert's your father's brother. (For newer vehicles,basically after WWII, I have a push button that has two alligator clips on a long cable that clip on the starter solenoid and I just punch the button to crank the engine. A one person job. The old stuff needs the wife to push the floor starter lever.)

[R.White]

The advantage, as I see it, to having a screw in compression tester is that you (or rather I) can dispense with the disgruntled other half. Just screw in the tester and hit the starter. Mine has a large, easy to read dial with a pressure release button on the side. There are different adaptors which screw into each other depending on the size required. A nice piece of kit.

Tomorrow I will get on with checking the timing regularity with the strobe light. I thought perhaps I could use a 12 volt battery charger rather than trying to lift the big heavy duty battery out of the Range Rover?

Ray.

[ply33]

Tomorrow I will get on with checking the timing regularity with the strobe light. I thought perhaps I could use a 12 volt battery charger rather than trying to lift the big heavy duty battery out of the Range Rover?

Might depend on the the charger. If it is an old cheap one with poor filtering and voltage control you might have a problem.

Got a set of jumper cables? Could use them as an extension cord to power the timing light. Just make sure the clips are well insulated from each other.