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Misfiring Dodge.???


2door

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Alright chaps,

I have a Dodge WC54 that misfires under load, if you go down a gear & try and charge up a hill it misfires & seems to be popping back through the air cleaner. if you drive round nice & steady everthings just fine even on the hills. if you go past half or threequarter throttle on a hill the problem shows its self.??

 

recently re-cut valve seats, new valves, skimmed head, fresh headgasket, reconditioned carburettor, new coil,rotor arm, distributor cap, plug leads, spark plugs, fuel filter, fuel pump recon kit...the only thing i'm not sure about is the electronic ignition conversion its had, this was fitted sometime possibly 3or4 years ago before i bought it. does anybody know anything about these are they reliable etc....??? if you increase the revs whilst watching the timing marks with the timing light it all seams to be advancing as it should....

 

Any thoughts i'd be pleased to hear them.??

All the best, 2door

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You have a lot of new stuff on there, difficult to tell.

 

If I had to guess, the static timing is wrong and it is advancing too far under load, or something along those lines. First thing I'd try is retarding the timing two or three degrees and give it a try - remembering where it was to start so you can put it back, of course.

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Hook up an undamped vacuum gauge below the throttle plate (about £15 off your favorite auction site) and see what that is telling you before you change anything.

( If you'r not sure how to read the various needle responses a quick google will give you the responses for a whole range of faults).

The advantage of using the gauge is it gives the ability to observe the function of the engine and it's various interrelated components, ie: valves, ignition system, rings, head gasket, carb settings ect in the dynamic state and most importantly in the physical condition that the engine is in currently.

 

As an aside it's worth remembering that workshop manuals give data for factory fresh engines running on fuel blends that were current 75 years ago.

 

Pete

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When you did the valves did you fit new valve springs? old valve springs are prone to losing their tension and often break, a weak inlet valve spring would cause the popping back through the carb, I don't think this could be anything to do with timing, the engine would have to be so far advanced it would be pinking even on a light throttle

Edited by Nick Johns
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i asked this question year ago on Gordon's forum about electronic ignition Phil P came up with 7 degrees. Works for me on both mine. :-D Though did have a similar problem with my WC51, early this year, most embarrasing. Cause was even more embarrasing, one plug lead had rested against the bottom of another plug, and partially melted.

Edited by Tony B
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Thanks for your responce guys,

Gordon M

I will try retarding the timing, not sure where it is at the mo as i only have a T.D.C mark. all the others have been lost to corrosion..!!

 

FV1609

Its always done it but before i did the work on the valve gear it wouldnt pull its self up any hill.....

 

Pete Ashby

Thanks Pete, i'll try & borrow a vac guage....

compressions were as follows before i did the valve gear.....

Cyl 1 50psi Cyl 2 40psi Cyl 3 130psi Cyl 4 90psi Cyl 5 135psi Cyl 6 70psi And After.....

 

140psi 130psi 135psi 128psi 140psi 140psi

what symptoms am i looking from the vac guage..??

 

Nick johns

I didnt fit new springs....

can you explain what you mean by they would cause popping back, as arnt the valves held shut during the compression stroke by compression.?? only guessing...

 

Tony B

i,ll try 7degrees & report back,

 

Thanks everyone for your help, keep the sugestions & ideas coming...

All the best, 2door..

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nobody has mentioned the firing order

 

If the order was wrong it would barely move the vehicle. :-\

 

It COULD be anything, but it is easiest to start with static timing, then check for partially collapsed fuel hose, carb problem, vacuum leak, etc, etc.

 

With electronic ignition I'd guess you needed to experiment, as the modern fuel and running characteristics will be way different.

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Thanks for your responce guys,

 

 

Nick johns

I didnt fit new springs....

can you explain what you mean by they would cause popping back, as arnt the valves held shut during the compression stroke by compression.?? only guessing...

..

Its the spring that shuts the valve, if the valve is not shutting properley there is low/no compression, the engine may appear to run fine at low revs but a weak inlet valve spring will cause the valve to bounce at higher revs so its not closing entirely, hence the compression will blow back into the inlet and out of the carb

Edited by Nick Johns
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Something to check is that you are running with a negative spark rather than a positive spark which will be less effective at high load & high revs.

 

Are the coil LT connections the right way round? Are you certain that the coil is of the correct earth polarity for the set up in your vehicle?

 

If the polarity of the earth has been changed sometimes people simply reverse the LT connections on the coil so as to give a negative spark. But that way you lose appx 600v of HT compared using a coil designed for the specific earth polarity of your vehicle.

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i bow to your technical knowledge but i bought a jimmy from somebody that times up multibanks ( 5 dodges) drove it for 15 miles untill it gave up got recovery home next day was baffled untill i saw the frost on the base of the carburettor i had seen it before the firing order was wrong swapped two leads and it purred it was timed as a bedford not a gmc also i went to kent to buy a command car the vendor took me for a road test which was good but it ran like a dog when we returned i raised the bonnet and swapped two leads then he mentioned the two traders that were there the day before

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Thanks for your responce guys,

 

 

Pete Ashby

Thanks Pete, i'll try & borrow a vac guage....

compressions were as follows before i did the valve gear.....

Cyl 1 50psi Cyl 2 40psi Cyl 3 130psi Cyl 4 90psi Cyl 5 135psi Cyl 6 70psi And After.....

 

140psi 130psi 135psi 128psi 140psi 140psi

what symptoms am i looking from the vac guage..??

 

 

 

Thanks everyone for your help, keep the sugestions & ideas coming...

All the best, 2door..

 

The vacuum gauge can be used to diagnose all manner of ills not sure how this will post. If you can't read it type 'using a vacuum gauge' into google and click images there are a number of charts listed just make sure you do the tests on a warm engine. Used in conjunction with your compression tests it can help to narrow the field in terms of what may be wrong.

Pete

That seems to be readable for the Smiths chart click on the chart it'll open in another window, then click on it again and you should see a magnifying glass appear click it and it comes up large.

49550.jpg

 

13508995_10153824406429397_5453524888593764768_n.jpg

Edited by Pete Ashby
checked uploads for clarity
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i bought a jimmy from somebody that times up multibanks ( 5 dodges) drove it for 15 miles untill it gave up got recovery home next day was baffled untill i saw the frost on the base of the carburettor i had seen it before the firing order was wrong swapped two leads and it purred it was timed as a bedford not a gmc

 

That is odd because firing order for a GMC and a Bedford is the same !

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i hear you nick,

down hill she'll do nearly sixty with no side effects & the compression readings are way higher than the specifications in the manual, sugesting the valves are sealing real good.

i'm going to try the timing tomorrow and let you know, 2door....

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I teach guys to work on forklifts, and I can not believe how few even know what one is let alone how to read one.

 

I learned to use one as a kid to set timing. I could not afford a timing light.

 

They will tell you most anything there is to know. From exhaust being stopped up to valves sticking.

 

VACUUM20GUAGE20CHART20SMALLER.jpg

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Going from memory firing order for 6 cylinder engine either 153624 or 142635 some manufactures ie RR and Jaguar start no1 Flywheel end, others no1 crankshaft drive damper- pulley end. Daimler diesels had timing gears at the Flywheel end of the crankshaft.

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checked the timing with a strobe light today, i've only got a mark at TDC as i said before. but my friends timing light can sort all that out and says its set at 8 degrees & C/O reads four & a half percent. so i dont think its advancing its self too much on the hills.....

 

ive managed to scrounge a vac guage today so ill be plumbing that in tomorrow & will let you all know what i find.....

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Interesting point FV1609, ( Negative Spark )

my low tension wires are Red & Black & they go from the coil to a small box in the dizzy, can you please explain how to connect it up to the coil to get a negative spark & ill check that its wired that way round tomorrow,

All the best, 2door.....

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I have a "44" Wc 51 and encounted more or less the same type of problems on mine.It really missed coming off of a round about

I did almost everthing you did, and then replaced the Carter Carb with a new one. It totally transformed the vehicle, there is no more misfire and I would say much more poke........

Not saying its the same problem as you but that sorted mine.

Friend of mine has a VC3 popping back through carb also, after a number of "old boys" looked at it, whith the aid of a blanket over my head and distributor I found the base plate loose and sparking.....

Two similar problems, two totally different outcomes........

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