The V8 Owners Forum -

Here's my experiences from a ballasted system

When cranking, the ballast resistor should be bypassed, giving you close to the full battery voltage at the coil. When I didn't have the correct voltage, the culprit was poor wiring (in my case caused by corrosion)

When running, the ballast resistor should be in circuit, giving you about half the alternator voltage (or half the battery voltage if the ignition is on without the engine running)

My experience says that 4.5V at the coil will just about keep the engine running, but with a lot of misfiring. however, 8-9V will not give a strong enough spark to fire the engine to start with.

If you have a coil for an electronic ignition, it will almost certainly be designed to run at 12V, and so will give you a weak spark when running with a ballast resistor.

My suggestion would be the same as Chris has suggested - get a distributor from a later engine (you may need to upgrade your oil pump to get the correct drive for this) and use a fully 12V system

Bryan

Marco?

Sorry I missed the progress on this thread.

The dizzy you have does look like the early 35DE8 Opus unit also known as opeless, they are known to be problematic even when matched to the correct components and will be 35+ years old anyway.

I would chuck the 35DE8 and buy a 35DLM8 which has the small black box which is the amp on the side of the body of the distributor. this requires a Lucas DLB198 12v or equivalent coil with a full unballasted 12v supply.

Your wiring system is set up for a ballasted sytem as it's taking power from the starter motor when cranking to give a higher starting voltage I suspect that you may have an additional ballast resistor in the wiring harness so all this needs to be disconnected and bypassed with a full constant 12v supply, so find a full 12v supply that is live with ignition on only.

Probe distributors had some 35DLM8 distributors for I believe £125 and the correct coil will be approx £30.

Rimmers tend to be somewhat expensive for most rover components.

Kevin.

OK, I spoke with Rimmer Bros (thanks for the info). They have stated that they have the ballast resistor, but couldn't tell me if it should show 12V at the +ve side of the coil (so I don't really know if mine is knackered or not). They also said that they don't have any special ignition coils for the ballast/Opus type distributor.

Should I just buy another coil and a resistor and try it anyway?

I did wire the coil direct from the battery to give it a 12V feed, the spark was bigger and it was trying a bit harder to fire, but it still didn't start.

Did you try powering the coil from a _different_ 12 battery, so you get the best voltage you can on it?

Chris.

if i was you ,before you buy anything .i would check the wiring from the coil back towards the ignition. if youve already changed the coil and its still the same 4.5v reading, its probley a wiring fault. rich

Marco

The ballast resistor is just a resistor and simply reduces voltage.

I think and bear in mind we are trying to diagnose a problem at long distance that you have a mismatch of components.

if you dont want to change the dizzy and coil, then you have got to find out what the 35DE8 distributor requires in terms of coil and voltage supply, also not knowing where your loom came from and whether it has an additional ballast resistor in the ignition circuit which I suspect it has, doesn't help.

I would suggest contacting H & H ignition and ask for some advice for the correct set up for the 35DE8 ie correct coil and voltage supply.

i know it's confusing and even if a system requires a 12v coil if it has the wrong resistance then the dizzy will not work.

http://www.h-h-ignitionsolutions.co.uk/

One other thing you could try bearing in mind that the plugs have probably been well and truly soaked in fuel, is a fresh set of plus and with a full 12v from the battery to the coil assuming it is a 12v coil and see if it will start.

Kevin

I'm not keen on elastic trickery stuff but I see it as if it is running 2 resistors

If it was one there would be about 9 v coming out of the resistor set up

If this in turn was run through a second resistor you would get about the 5v level

If course please read my first sentance and this could be absolute rubbish

Ian

OK guys, thanks again for the advice.

I spoke with H&H - very helpful guy. He said the same as you guys, that the best thing to do is to just ditch the ballast resistor and bypass it.

He also said that the Opus distributor set up was pretty unreliable and prone to all sorts of problems. He could supply a new electronic unit with distributor & coil for £200, one that was used on later Land Rovers. Might be worth doing now to make things better for the future. The only pain is that I will have to take the flamin engine out to do it.......and I only just got it in there!

I'm going to give bypassing the ballast resistor a go first and see if it makes any improvement. At least if I can get it to run then I can get some other stuff done. Right now it's stranded on my ramp!

So, if I bypass then am I right in assuming that:

1) I just use the two wires that currently come out of the distributor?

2) does one go to the +ve side of the coil...where does the other go (to earth or to negative side of coil??)
3) I will check that the feed directly from the ignition to the coil is a good 12V, if it is and I can eliminate the ballast unit altogether then it will certainly help.

I'll keep you posted........it's amazing how one minute you think you're moving forward.....the next you are going back!

You should be able to remove the distributor without taking the engine out - I certainly can on mine.

1) Remove distributor cap and points
2) Remove seats to gain access to front of engine hatch
3) Remove hatch cover into engine bay
4) Release dizzy locking clamp
5) Remove Dizzy

If it hits on the bottom of bulkhead window cross bar you may need to remove engine mounts and drop it a couple of inches (support sump on wood on trolley jack)

People on forums think space it tight - try a GT40 we fit things where there is no space

Ian

To remove the ballast resistor, just connect a wire between the two sides of it. Leave all the other wiring as-is. Or take it out and connect the two wires together.

Ian Anderson wrote: People on forums think space it tight - try a GT40 we fit things where there is no space

Ian

At least you can get to your spark plugs....

Chris.

At least you can get to your spark plugs....

Chris.[/quote]

Yes but let the headers cool a bit first - I do have the scars to prove what happens!

Ian

true......we can get to our spark plugs......but like Ian (that made me laugh Ian).......I also have the burns and scars from being a bit too impatient in trying to get them out!

As a matter of interest, which plugs would you guys recommend?

Ian....you might be right.....it might just be possible. I've had to move my whole engine forward by about two inches to get my driveshafts to lign up straight......now my dizzy is almost jammed under my rear bulkhead window! dropping the engine might give me enough room though.

Such a big car...so little space for anything!

OK...an update on the problem.

I have fitted a new distributor cap and rotor arm. I have bypassed the ballast resistor completely and I am running the coil with +ve 12v supply direct from the battery. I have disconnected the vac advance from the carb to the distributor. The car nows runs, but when I attempt to set the timing with the strobe I can only get so far, then just as the timing marks are approaching the pointer (within about 10-20 degrees) the timing light stops working and the car runs rough.

I have reset all the idle screws on the Holley so that is OK. I can get it to tick over about 1000-1100rpm, but no less really. I have also disconected the electric choke and jammed the choke flap open once the engine is warmed up.

If I put a meter on the coil and turn the distributor, my voltage drops over a section as I turn it round - any ideas? I could just be the crappy Opus unit as you guys have suggested. I don't mind buying a new distributor and coil.....I'd just hate to do it and find that's not the problem.

what timing setting are you trying to get??, what rpm is it at tickover ??,and does it idle ok?? have you set the timing at roughly 6 btdc to start with ??.and have plugged the advance pipe?? rich

Hi Bones,

The timing pulley is marked with white paint in two positions - one I believe to be TDC, the second looks like about 6 deg. It's a standard pulley wheel I'm running.

Tickover at the moment is about 1000-1100rpm. It won't go any lower than this.....it just gets really rough and dies. If I mess around with the distributor it doesn't help....unless I move it miles away and the thing races like hell.

It does idle reasonably well, but at 1000-1100rpm.

I removed the advance pipe from the carb......but I didn't plug it. I take it then I should I do this? I just thought removing it would stop the advance from working, but I guess it may not be helping the carb.

When I set the timing static, I took note of the rotor arm position at TDC, then turned the distributor to align an HT lead position at roughly the right spot, then I put the leads on in the correct order. It's certainly better than before, but still a long way from being right. Any ideas why the timing light chucks it at a certain position. It's almost as though something is breakind down and there is not enough spark to run it any more. The light works great when the timing marks are way off - the engine runs great but really fast. It's weird....