Champion WCX 600 bow tie caps

[cactusman]

A quick update. SNGB have sent me six new caps that hopefully have carbon resistors. Measured resistance is between 9.00 k and 10.76 k ohms so that does indeed suggest that, based on the wide variation, they are indeed fitted with carbon composition resistors. All the others I have are within 0.1% of their stated value (5000 ohms) and those i opened had metal film resistors.......so the caps are in and now time will indeed tell. If one fails I shall open it and see...mean time thanks is due to Julian Barratt at SNGB. I shall keep him posted as also the forum.

[mark10337]

Shame they didn't send 7 and you could have cut one open to check Are these then with the bow-tie style logo etc.? Interesting they could get alternatives so quickly.

[cactusman]

Yes....bow tie types. I was expecting one to chop open but they sent six They look identical to the crap ones I had before...BUT...they test more like originals and Julian assures me they are carbon resistors...so they are on test....did a 10 mile run this pm...fine so far although very hot here in the UK...the driver wilted....

[Heuer]

I will remind you again that you do not need resistor plug caps if you are using BPR5 plugs (which you should most certainly should be if you have any electronics in the car). If you are wedded to bow tie caps you need to find a way to short out the resistor. Alternatively use the WC548 oval caps from Speedy Cycles or Green Spark. As far as we know these were still used well into 4.2 production.

[cactusman]

A resistor cap does the same job as a spark plug with a resistor. My car has electronic ignition and an electronic conversion in the tachometer and an electronic version of the RB340 and an electronic version of the otter switch. All work just fine. Correctly designed electronics should be resistant to all but the most savage electromagnetic interference and there are more savage emitters of emi than a spark plug...although it is a legal requirement to have suppressed leads be they resistor plugs, resistor caps or resistance leads.

[cactusman]

Quick update. Done about 300 miles on the caps from SNGB. So far so good. I 're tested their resistances yesterday after a very hot ride back from Cricklade. Range was 8530 ohms to just over 9300 ohms so their resistances have actually dropped a bit....

[Heuer]

A resistor cap does the same job as a spark plug with a resistor.

Sadly not our experience as EDIS/Megajolt owners. I helped Ray Livingston develop his kit but final release was halted due to an intermittent misfire. We tried everything to understand what was going on especially as the misfires occurred at the same points on my test route. HT cables were modern silicone suppressed with moulded caps and everything was correctly earthed; other testers in the US could not replicate the problem. After a lot of research I decided to try replacing the BP5 plugs with BPR5 ones and the problem disappeared immediately so their fitment became mandatory for the kit. Hotly debated as some of the EDIS/Megajolt kits gave no problem but the EDIS developers confirmed that resistor plugs were indeed necessary.

My own theory is the EDIS/Megajolt is sensitive to EMF and my test route ran over buried mains cables which exacerbated the misfires, hence they occurred at the exact same spots every time. In the US, with open roads the likely-hood of picking up extraneous EMF was much reduced. Now why the resistor plugs suppressed this and the HT cables did not is a mystery but given a set of resistor plugs costs £10 (and they are standard fit on all modern cars) I figure they are worth fitting come what may. With smartphones, sat-nav's, DAB radio and electronic ignition on board performance may be retarded especially in built up areas with lots of EMF.

You can fit suppressed HT leads, plug caps and resistor plugs at the same time and they won't affect engine performance.

One observation - why are the carbon Champion plug caps nominally 10k when originally they were 5k as are the ceramic resistor ones?

[cactusman]

Can't answer as to why the caps are 10k. Whether the resistor is in the plug or at the top can make no electrical difference as it is still in the same series length of conductor. If the EDS megajolt were sensitive to radiated interference,especially from buried mains cables (which I'd very much doubt) then in my view that would be down to a design flaw....which I also doubt. Much more likely in my view would be the installation and more especially the grounding arrangements within the car and not just the ground connection to the megajolt itself.
Different I'll grant you but anyone who builds audio equipment will tell you that ground loops and earthing issues can cause all sorts of hum issues and noise issues. Any high power systems should have all earths brought separately to a single point....a star earth. Earths linked together serially and then to the source of power can cause all sorts of mysterious effects....and given the high pulse currents in an ignition system and the use of the car as the ground I'd suspect mystery misfires could be caused by ground loops if not by something more down to earth like a loose connection.

[Heuer]

This is the difference between standard and resistor plugs:



"At the moment the spark jumps the gap it causes a high frequency burst of energy, this is known as RFI (radio frequency interference). This is why resistor spark plugs were introduced in the mid 1960's. Placing a resistor within the spark plug suppresses the RFI. Without resistor plugs in your car you can experience static on your radio as well as interference with other sensitive electronic equipment. Some later model vehicles as well as newer Powersport engines must use resistor plugs for a proper "talkback" to the electronic ignition. As a rule, performance is in no way impaired by resistor spark plugs."



My previous ignition system was a Magnetronic and clearly not affected by the type of plug.

[rfs1957]

Can anyone update their current experiences with the bow-tie 10K-ohm WCX 600 caps ?

Mine came from AES in Tenbury, just last week, but are evidently from the same original source as everyone elses.

Has anyone used these with a Megajolt ? I'm aware of the resistor-plug debate regarding those.

Not used yet, and initially they will be used with standard points distributor.

[abowie]

Nothing recent sorry Rory although I have had them fail in the past.

Failures happened very early, within an hour or so. What would happen is that the car would start to miss on one cylinder, then two, then rapidly escalate and would break down completely with hard throttle or increased revs. It was possible to limp along just above idle speed.

The caps are a screw fit into the wire. What I'd do would be to fit them and go for a drive, taking your old caps with you.

If they fail you can then just take them off and refit the working ones. Failed caps had essentially infinite resistance when measured.

[Heuer]

I replied here: https://forum.etypeuk.com/viewtopic.php ... 05#p133805

You need resistor cables with moulded plugs to use Megajolt. You also must use resistor plugs as the system is very prone to EMI and RFI. It is very difficult to get the WCX plug caps to make a high integrity connection to the silicone leads. You are trying to screw a big brass terminal into the carbon string core of the HT cable which is as friendly as a wet eel to handle.

Also the low grade resistors in the caps cannot survive the EDIS voltages for long. Those caps are purely decorative unless you can source originals.

Chapter and verse here: http://www.magnecor.co.uk/faqs.asp#2

and here (very worth reading): https://www.magnecor.com/magnecor1/trut ... k%20energy

Magnecor can provide you with custom cable lengths with the correct moulded EDIS plugs and plug caps:


The effectiveness of the EDIS system relies on end to end integrity of the cables hence gettin g Magnecor to make you a set is the best option.

[MarekH]

I just made my own plug leads by cutting up the old Lucas ones that came with a v12 HE distributor and mating the Ford coil pack connectors onto them. Plugs are resistor plugs.

I am running the coils directly from Megasquirt using BIP373s rather than Ford's EDIS and it all seems to have been running fine for best part of ten years now.

Metal film resistors won't work for plug leads. Those of you familiar with valve amps will know that old fashioned carbon resistors have a much higher voltage (and wattage) rating than the high precision metal film which generally are only good for lower currents and voltages.

Anything that has electronics in it will want resistor plugs.

It doesn't much matter what the resistance value is - anything between 3k and 20k will work. My Lucas leads are all different lengths and thus different resistances.

Do make sure you don't buy knock of cheap spark plugs by accident.

kind regards
Marek

[Heuer]

Rory

If you are wedded to period caps you could try Champion WC548 'oval' caps which have no resistor and would be original to your car. Excellent reproductions are available here: https://steadfastcycles.com/collections ... ch-triumph
Despite the photo they are all black, not black/gold!

Originals (ignore the plug in suppressors):


Steadyfast Cycles repro:


These would be period correct for all 3.8 cars up to mid 1964 after which the bow-tie caps became standard. About the only problem you will have with these caps and the silicone cable is getting the copper spike into the carbon conductor. But other than that they will work.

[gtjoey]

Julian, IMHO, I went down this road once years ago. They are junk!
Unless you need them for a concourse car that never moves. Call Beeres he will make you the c/d type wire holder along with wires. It look the part and you will be done for life!
GTJOEY1314
Driving thousands and thousands of miles each year in an etype, JUST BECAUSE...........