Lucas 'Opus' system 35DE8

Nige · Post by **Nige** » Sun May 06, 2007 3:51 pm

I am running this Lucas 'Opus' system 35DE8 distributor system from an SD1 but have a lot of starting problems, especially when the engine is hot, which I think is a common problem with these distributor. Picture of the dissy is on:
http://www.rpiv8.com/electrics-1.htm

At the moment there is a Ballast resistor ( http://www.v-8.org.uk/forum/viewtopic.php?t=578 )wired in. Is there any way I can bin this Ballast resistor and just wire a 12V coil straight, or do I need a new distributor?

If I can wire it straight, does anyone know which wires go to where?
I think my coil is already 12V, would this cause a weak spark as the system was designed for a 6 or 9V coil

Any advice would be appreciated...[/img]

Pocket rocket · Post by **Pocket rocket** » Tue May 08, 2007 9:36 pm

I was just speaking to JRV8 today about this unit and I'll pass on what (I think) he told me - the silver box is not just a ballast resistor but also a unit to send some sort of signal to the workings inside the distributor (might have been the otherway round but he did say it wan't an amplifier as such). Hence you can't just swop it for a "normal" resistor or remove it from the circuit unless you change the distributor. He did say there's nothing wrong with a DLM8 Dizzy

Hope that helps

Nige · Post by **Nige** » Fri May 11, 2007 1:53 pm

Thanks for the reply Pocket Rocket,

In the old V8 forum which this replaced, there was a discusion on the DE8 silver box. They concluded (and from the RPI website) that the DE8 had the amplifier circuitry built into the distributor body and an external Ballast resistor (silver box???) but the later DM8 and DML8 distributors had external amplification and ballast resistor. http://www.v-8.org.uk/snitzforum/topic. ... IC_ID=4083 . Not sure if anyone can comfirm this?

If this silver box on the DE8 system is just a Ballast Resistor, does anyone know how it should be bypassed?

Also, did the RV8's which had the DE8 ignition system have a 6V coils standard?

If i've a 12V coil where there should be a 6V, i'm guessing it could be causing some of my problems. The coil would not be getting charged fully and giving a weak spark?

Alley Kat · Post by **Alley Kat** » Fri May 11, 2007 3:26 pm

Far as I understand it, DE8 aka "opeless" has amp built into dizzy itself. There there was the DM8 with amp in a box remote from diz, with clip to mount the coil on it. After that came a regressive step, with amp mounted to dizzy (so more susceptible to heat & vibes than the prv version).

My DM8 didn't have a ballast, no idea if the donor car did originally or not.

If no-one else here confirms the rest, it'd be worth a chat with jrv8 or Real Steel etc

stevemedlock · Post by **stevemedlock** » Mon May 14, 2007 7:43 pm

Nige, How certain are you that your starting problems are caused by the distributor?

Despite the 'legend' my opus system was very reliable and gave a good spark. (I only replaced it to try to get a more appropriate advance curve.)

Is it worth trying a later distributor to see if the prob disappears or remains?

Steve

Nige · Post by **Nige** » Tue May 15, 2007 9:48 pm

I'm not certain the problem is with the distributor, but from all the bad reviews i've heard from them makes me suspicious.

I think the problem may be due to a weak spark, caused by either the bad distributor or maybe the coil itself. It's not too bad starting cold, but when the engine is hot, it realy struggles. Even though the battery is good, using jump leads from a running car (~14V) normally gets its started straight away again, even when its hot. I'm guessing from that the extra voltage may be increasing the coil voltage a little more, and just enough to get that strong spark and re-start the engine. Does that make any sense or could that happen??

This is the reason I am wondering if a 6V or a 12V coil should be used with the DE8 system or if I can throw away that ballast resistor to increase the coil voltage.... Can anyone let me know??

I got the carbs setup recently on the rolling rd so the mix should be right and the tuner said the engine was strong and in good condition... He did mention that the carbs themselves could probably do with some new seals because they were emptying the oil from the dashpots.... Not sure if some thing like that could cause starting problems??

I wouldn't mind trying a later distributor but rover V8's are rare where I am and I'd prefer to make sure I'm using the right coil first before I go changing it out..

Anyone be able to answer if I should be using a 6V or 12V coil?

Cheers
Nige

Post by **katanaman** » Wed May 16, 2007 7:55 am

Just a thought but if you have a week spark when cranking the engine it could be that your balast bypass isnt working. There should be a 12v wire going straight to the coil when the starter is engaged. usually direct from the switched side of the starter motor. Check that you have 12v at the coil when the ignition is in the start position.

jwriyadh · Post by **jwriyadh** » Wed May 16, 2007 6:29 pm

The correct coil for a 35DE8 is a Lucas 22 C 12.

All the info I have, if it helps.

My LR with 35DE8 runs fine with a bog standard 12 volt coil.

jw

Nige · Post by **Nige** » Wed May 16, 2007 10:20 pm

Thanks JW, I tried to find info on that standard coil but haven't come across wheather it's 6V or 12V and the Haynes manual doesnt say..

The Ballast switch might be the problem.... Is it internal to the silver 'ballast resistor' box pictured here? http://www.v-8.org.uk/forum/viewtopic.php?t=578 . The only wires going to my coil are the two connected to the silver box as shown in the schematic posted in the same link above (post 2). If the switch is internal to the silver box, I asume if I'm getting 12V to the Black wire in that schematic, I should be ok?

I tried measuring the coil voltage with the engine not running and the key switched to where lights are on on the dash. The voltages seem to be very low (+ of coil to engine earth is just +4.8V, - of coil to engine earth is +2V. + to - of coil is just under +3V). I'm guessing this is something to do with the type of electronic ignition and the voltage depends on how close the metal rods are to the magnetic pick-up in the distributor body?? Does the voltage ramp as the disk spins and gets closer to the pick-up before discharging and sending the spark? I will try to get a socket and spin the crank by hand (coil lead disconnected of course!!!) and see if the voltage ramps up to a normal level...[/url]

jwriyadh · Post by **jwriyadh** » Thu May 17, 2007 6:03 pm

One of the terminals on the ballast resistor is for connection to the starter solenoid, (small tag). This connection provides battery voltage to the coil pos while the starter solenoid is operated and the engine cranks.

Check out the 35DE8 wiring diagram posted on here during the last couple of months.

jw