scudderfish
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| posted on 27/2/09 at 12:09 PM |
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RV8 killing coils
Went out for a blat yesterday and conked out after about 20 miles. Nice recovery man pointed out that my coil was shagged, it was hot and with the
ignition on one side as showing a voltage of only 1-2v (the other was circa 12). Got a lift home and fitted a new coil this morning. Nice sunny day
so i go out and make about 250m before the same thing happens. Any ideas on what could be causing this?
It's a bog standard 3.5l running on carbs.
[Edited on 27/2/09 by scudderfish]
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theconrodkid
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| posted on 27/2/09 at 12:15 PM |
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sounds like wrong coil ie points coil and electronic dizzy?
who cares who wins
pass the pork pies
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DanP
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| posted on 27/2/09 at 12:20 PM |
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Have you got a ballast resistor fitted? IIRC the RV8 uses a 9V coil (it bypasses the ballast on cranking with a feed from the starter) and if you ran
without a resistor you might kill the coil.
Hth
Dan
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Mr Whippy
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| posted on 27/2/09 at 12:22 PM |
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quote:
Originally posted by DanP
Have you got a ballast resistor fitted? IIRC the RV8 uses a 9V coil (it bypasses the ballast on cranking with a feed from the starter) and if you ran
without a resistor you might kill the coil.
Hth
Dan
yip old fords used this method too. If the coils getting hot to touch then chance are its too high a voltage for it
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mark chandler
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| posted on 27/2/09 at 12:30 PM |
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If you unpick a RV8 loom you will find one of the wires to the loom looks a little odd with some writing on it, its a resistor wire so you do not have
a solid resistor as such.
Usually the points melt before the coil packs up! Have you got points, if not none of this applies.
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Mr Whippy
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| posted on 27/2/09 at 12:34 PM |
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had this the first time I put the falcon on the road, points lasted less than 500miles with a huge blast crater in the middle and pathetic engine
power, then I remembered about the resistor wire 
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scudderfish
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| posted on 27/2/09 at 12:37 PM |
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To be honest, I'm not sure what I've got, I didn't build the car and I'm at the bottom of the learning curve. A nice
neighbour just helped me tow it back to the driveway. I'll go and take some pictures of what I have to post up.
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scudderfish
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| posted on 27/2/09 at 12:50 PM |
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Ok, I've put some photos up at http://picasaweb.google.com/dave.g.smith/BlownCoil
I'm suspicious of the lump of insulation tape coming out of the top of the module behind the coil, I don't know what it's purpose
is.
When I got the coil this morning, the bloke in the shop picked it out of his book as one for a RV8, the original one had no useful markings on it.
The new one was for electronic ignition.
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Mr Whippy
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| posted on 27/2/09 at 01:31 PM |
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coil might be right but you need to get a meter and check the voltage supplied to the coil both while the starter is on and when the engine is
running. If it’s meant to have a ballast resister then it should 12volts when cranking and less were running. Looks more a general coil to me as it
has no markings saying it is for that ignition module. Wee bit of research needed, guy who sold it to you could have been talking b$ll$cks
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scudderfish
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| posted on 27/2/09 at 01:54 PM |
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The box the new coil came in says "Electronic Ignition Coil"
Once the coil cooled I got 12v on both sides of it, but as soon as I crank the engine the - side goes down to 1.4v (after the cranking has stopped).
The engine won't fire so I can't say what it is when it is running.
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02GF74
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| posted on 27/2/09 at 02:06 PM |
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quote:
Originally posted by scudderfish
Once the coil cooled I got 12v on both sides of it,
If the points are open, then that is what you will see since the coil is open circuitbut as soon as I crank the engine the - side
goes down to 1.4v (after the cranking has stopped).
This would imply points are closed hence coild is earthed, 1.4 V is a bit high though The engine won't fire so I can't
say what it is when it is running.
To check coil, disconnect all contacts and measure resistance across the input terminals
3 ohm = non balast
1.5 ohm = ballast
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DanP
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| posted on 27/2/09 at 02:10 PM |
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The fact that you have 12V when it is just sat there suggests to me that you have no ballast resistor, can't confirm but i would think it should
be sat at 9V when the ignition is on.
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wilkingj
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| posted on 27/2/09 at 02:19 PM |
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Welcome to owning a kit car.
Dont worry, there is plenty of help on here.
You need a Ballast resiistor if you have a coil type that needs a ballast resistor, if not then you dont need one.
Is the Dizzy the one with a big box of leccy gubbins on it?.
You need to identify the type of Dizzy and electronics first.
Once you know what that is, then you can investigate what the correct coil and wiring is for that dizzy.
Also when you have a ballast resistor fitted it drops the voltage on the live side of the coil down to about 8 Volts.
So measure the voltage on the live side of the coil. Is It 12 or 13 Volts, or is it about 6 or 8 volts?
If you have a ballast type coil, and DONT use it with a ballast resistor, you will be feeding 12Volts into a coil designed to work at 8Volts. It will
get HOT and eventually fry itself!
The point of the ballast resistor, is that when cranking the engine, the Battery voltage drops, and hence the sparks are poor. So they use an 8 Volt
coil, with a resistor to drop the voltage for normal running.
They when you start the car, they short out the resistor (or just feed 12v direct to the coil via a relay) for the cranking period.
This boosts the sparks by feeding the 12V into an 8 Volt coil (remember ther is a volt drop when cranking the engine, as the starter is drawing 2-300
Amps, and dropping the voltage).
So when cranking, the coil still gets enough volts to give proper sparks to start the engine.
I fitted a ballast coil and resistor, and it was a pig to start, until I fitted an additional 12v feed direct to the coil, which only operated during
cranking the engine. (You may not need this, as I dont know wht the electronics do on your car)
Personally speaking I dont like the Rover ignition. They always were funny.
Most people fit a Mallory Dual point Dizzy, or the more expensive Mallory Electronic Dizzy.
These give you a much more simple ignition circuitry. Downside is they are not cheap.
Another very good methid is to fit a MegaJolt system. These are very good.
It sounds like you either have the wrong coil, or you need a ballast resistor fitting.
I am no expert on the RV8 Electronic Ignition, but I know a lot of people dont like it.
As above, FIRST Identify what Dizzy and any electronics you have. Before just changing parts. ie Dont "Poke and Hope"
Spend some time on Google and research the types fitted to RV8's (and Land / Range Rovers)
Check your engine number against this page, it might help to tell you what your engine came out of, and hence its ignition system.
Linky
Just remember that its all fixable... but may cause you some head scratching, and loss of hair during the process
Finally... Add your rough location to your profile. Then people can see if they can offer help if you are near them.
1. The point of a journey is not to arrive.
2. Never take life seriously. Nobody gets out alive anyway.
Best Regards
Geoff
http://www.v8viento.co.uk
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robinj66
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| posted on 27/2/09 at 02:43 PM |
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Following on from above - look for the numbers on the side of the distributor.
A points dizzy will have 35D8 - usually needs a ballast resistor in the system and a ballast-suitable coil
An OPUS system dizzy will have 35DE8 - this system definitely uses a ballast resistor module (9BR) with three wires connected to each side. It needs a
coil suited to a ballast sytem
A 35DLM8 should have a black box (ignition amp) attached to the dizzy body
A 38DM8 has a separate (usually silver) igniton amp (usually) attached to the coil.
The DM8 & DLM8 both need an electronic 12V coil.
Once you have identified the type of distributor you can go on from there.
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scudderfish
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| posted on 27/2/09 at 02:50 PM |
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Thanks for all the help so far, I have a theory...
Info Dump
The engine number puts it in the range
10A00001A SD1 manual 9.35:1 CR 1976-87
Which is what I was informed (1984 SD1).
The resistance across the coil is circa 1 ohm which implies that the coil is expecting a ballast resistor. Although this could be misleading if the
coil is internally damaged.
The ignition module behind the coil has the following markings
AB12
47279A
3583
The distributor is just marked as Lucas and it doesn't appear to have any extras lumps attached.
In an earlier post I referred to a suspicious lump of insulation tape. I peeled this off and found two cut wires. If this was where the ballast
resistor was, it would explain a lot. I've fitted a coil (by the cross terminal measurement) that was expecting a resistor, but it has
previously been hacked out.
There are four wires coming out of the ignition module. One goes to the + side of the coil, one goes to the - side, and two are floating in the air
wrapped in tape.
I added another couple of photos to http://picasaweb.google.com/dave.g.smith/BlownCoil#
Does my theory sound correct? There was a ballast resistor on those two wires but it was cut out. I fitted a ballast coil and blew it as it was
getting full fat 12v.
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scudderfish
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| posted on 27/2/09 at 02:58 PM |
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quote:
Originally posted by robinj66
Following on from above - look for the numbers on the side of the distributor.
A points dizzy will have 35D8 - usually needs a ballast resistor in the system and a ballast-suitable coil
An OPUS system dizzy will have 35DE8 - this system definitely uses a ballast resistor module (9BR) with three wires connected to each side. It needs a
coil suited to a ballast sytem
A 35DLM8 should have a black box (ignition amp) attached to the dizzy body
A 38DM8 has a separate (usually silver) igniton amp (usually) attached to the coil.
The DM8 & DLM8 both need an electronic 12V coil.
Once you have identified the type of distributor you can go on from there.
Thanks for that
The dizzy has 35DM8 on it so 12v coil it is. Off to the factors again....
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scudderfish
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| posted on 27/2/09 at 04:31 PM |
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Hmmm, the shop reckons that they sold me the right thing so working on the basis they sold me a duff one, I'm getting a replacement tomorrow.
The coil is an Intermotor 11410.
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scudderfish
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| posted on 27/2/09 at 09:27 PM |
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A bit more digging around, it looks like I need a coil that is the equivalent of the Lucas DLB198. I'm going to take my multimeter along
tomorrow to make sure whatever coil I get does not have an internal resistance circa 1 ohm
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scudderfish
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| posted on 28/2/09 at 08:36 AM |
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The Intermotor 11410 is a direct replacement for the Lucas DLB198 according to the cross reference search on
http://partfinder.smpeurope.com/index.html. Maybe I just got a duff one. I'll post how the replacement goes in case anyone in the future
suffers this.
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scudderfish
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| posted on 28/2/09 at 12:01 PM |
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Well the engine didn't even fire . I cranked it over a while and gave up. I've put my battery on charge as a vain hope that it was a
bit sick after all the cranking it's done over the last couple of days.
Can anyone with a working Rover V8 with a 35DM8 dizzy please tell me the make and model of your coil?
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wilkingj
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| posted on 28/2/09 at 04:39 PM |
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I had an Intermotor coil on My V8 and it didnt like it and got hot.
Bought a Lucas one at a rally with the right ballast resistor, and havent looked back since.
1. The point of a journey is not to arrive.
2. Never take life seriously. Nobody gets out alive anyway.
Best Regards
Geoff
http://www.v8viento.co.uk
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scudderfish
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| posted on 28/2/09 at 06:47 PM |
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Well the battery was quite low so I'm leaving it alone overnight, then off to Halfords tomorrow morning to see what I can get.
The problem with the internet is too much information, giving me too many ideas. I now want to change the ignition amp (the random cut wires coming
out of it have shaken my faith in it) and do the modification documented here
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robinj66
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| posted on 28/2/09 at 08:03 PM |
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I was searching for info about the coil this afternoon but withoput any luck.
I have two rover workshop manuals and neither gives a coil for the DM8 dizzy (but they do specify coils for the DE8 and DLM8
If you can do the mod shown on the V8 Forum then that would be your best bet.
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scudderfish
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| posted on 5/3/09 at 01:45 PM |
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I did the mod and fitted a Lucas DLB198 coil. It has never started so easily in all the time I've owned it!
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Fred W B
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| posted on 5/3/09 at 05:04 PM |
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I finally gave up battling with the distributor on my pre SD1 rover, threw caution (and the credit card) to the winds, and ordered this from Paul at
V8 Tuner.
kit here
Image deleted by owner
[Edited on 5/3/09 by Fred W B]
You can do it quickly. You can do it cheap. You can do it right. – Pick any two.
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