Confusing - distributors for 3.9L V8

[MacMan]

Hi all,

Won't bore you with too many details, but the Disco disgraced itself the earlier in the week and left me completely stuck by the roadside. The problem appears to be to do with ignition timing. Was running perfectly, then backfired one very loudly and ended up getting a tow home from a mate.

All basic voltage tests for LT side of coil appear OK. On closer inspection, the amplifier tests OK in terms of resistances and there is strong spark from the coil to the engine block when cranking with the coil earthed to the block. This means amplifier works, but things get messy from the distributor onwards. Timing is now WAY out. The few times I have been able to get it running, the timing has to be advanced 60 or so degrees. Vac advance has been removed for testing (appears to be dead) but I have not been able to get it running long enough to put a timing gun on it to measure properly.

I have a mate coming to help see if we can nail down the timing with a light and then I plan to pull the distributor to check the gear at the bottom. Something is significantly unhappy!

I will pull it out and disassemble but I am not ruling out replacing it.

The distributor fitted is marked "ERR4740" and "38DLM8" and has the 3 pin amp module mounted to it. When looking at some UK sites there are numerous models with the amplifier mounted to the distributor body same as mine is.

What is the interchangeability between them? What are the differences between the 3.5L low comp and 3.9 low comp models, or between the high and low comp models?

The prices vary enormously even from the same supplier - eg LRSeries have the ERR4254 3.5L low comp for about £124, whereas the ERR4740 is £345.93!

Any advice from JC or other cluey folk gratefully accepted.

[Tank]

If you suck on the Vac. adv. pipe you should feel pressure and the arm on the other side should move, if you get no resistance when sucking, it's buggered, $128 last time I bought one.
Quote:"Timing is now WAY out."
I would be checking your timing chain, sounds like the cam/valve timing may be out.
Do you know how to refit your dissy to the correct timing?? Regards Frank.

[Pierre]

MacMan, where are you? I'm in Mooroolbark, and quite happy to lend a hand if you want. Have special tool 5284 to turn oil pump tang to engage with distributor drive if you want it.

Just about any distributor will work in a V8 with the correct control gear.
I'm not sure, however, about any changes to mechanical advance curves between LC and HC applications.

Rebuilt vac advance mechanisms from Performance Ignitions in Nunawading are about $70 core exchange.

HTH

Pete

[MacMan]

Vac unit stuffed. Tested. Stuffed.

Yep, I know how to set up static timing. TDC on #1 cyl, both valves closed following compression upstroke.

I guess that to verify the cam timing is still correct I will either need to take one rocker cover off or remove the timing cover. The rocker cover will be less work, but removal of the timing cover will also reveal the state of the woodruff engagement for the distributor drive.

Annoying stuff.

[MacMan]

MacMan, where are you? I'm in Mooroolbark, and quite happy to lend a hand if you want. Have special tool 5284 to turn oil pump tang to engage with distributor drive if you want it.

Just about any distributor will work in a V8 with the correct control gear.
I'm not sure, however, about any changes to mechanical advance curves between LC and HC applications.

Rebuilt vac advance mechanisms from Performance Ignitions in Nunawading are about $70 core exchange.

HTH

Pete

Hi Pete,

Thanks for the offer. I am in Sunbury. I've used a steel rod with a slot in it to turn the oil pump tang before. It's not too hard with trial and error, but the key thing will be to ascertain whether or not the change in timing has come from something inside the distributor (preferable) or timing chain/chain wheels.

I can's see why the distributors would change THAT much internally. Springs and weights would most likely be different to suit different capacities, compression ratios and fueling systems. The thing that gets me is that I have found multiple references to complete assembly numbers that contradict eachother. My printed genuine WSM lists the low compression 3.9L V8 distributor as #ERR1250 but I can't find ANY reference to that part number online. The one fitted was #ERR4740.

[LOVEMYRANGIE]

The vac advance wont cause it to jump out that far. If the vac advance doesnt work, you just wont get any advance, it wont alter your timing. I ran mine for about 2 years without a working advance before I could be bothered replacing it and all I had was a slightly sluggish engine at low revs. It could be something a little more serious or sinister....

Check the spark from each lead at the plug connection and test the strength.
If its dodgy, might just be a dud cap and rotor.

If you want, PM me your VIN number and I can check it on Microcat for distributor part number.

Cheers

Andrew.

[MacMan]

Not a dud cap or rotor - unless I am the most unlucky person in the world. I carry a brand new Lucas cap and rotor in the car at all times and neither made a pinch of difference.

I had it running again yesterday. All plugs on drivers side bank were fouled and today I will swap the others. Timing still advanced on what it should be.

More later.

BTW - thanks for the offer Andrew. I had a Microcat disc here but it has died. Going to download a new copy this morning.

[It'sNotWorthComplaining!]

If you have the spare coin ($660) turf the lucas system and get a scorcher dizzy from Performance ignitions in Nunawading Vic. And the prince of darkness will return to Hades and never bother you again.

[Traco]

Some possible causes may be the skew drive gear on the end of the cam or the gear on the end of the dissy shaft that engages with it. The skew gears can strip teeth due to lack of adequate lubrication.

Also with that oil pump you do not want to rev the engine too high when the oil's cold as it can place some strain on the distributor drive gears.

You may also want to check the bush in the dissy shaft. I had an Austin 1800 ute that once had the Lucas dissy shaft bind up and that threw the timing right out.

Does it idle ok? Does it fail only when the mechanical advance kicks in. If so it could be broken advance spring.

Those plastic tooth timing gears are also not the best - much better off with a proper double row steel type.

For the price of a new Lucas you may be better off replacing it with a Scorcher.

[SPROVER]

I just recently put a Scorcher Dizzy on my 3.9 V8 and it made a huge difference.I got sick of the OE crap and changed it.It cost me $600 from Performance Ignition but at least i dont have to worry about it again.:)
If you have the money go the Scorcher.Have a look in my Members rides under Sprover and you will see a pic of it there.

Cheers
Chris

[SPROVER]

Found it for you.



http://i289.photobucket.com/albums/ll208/Sprover/103_2233.jpg

[MacMan]

OK - update.

New plugs in all pots - they were all sooty, but I expect that's because it has been running awfully when it ran at all. It still won't idle without more than 12 degrees advance measured off #1 on pulley with timing light and is extremely hard to start. Even then, on both LPG and ULP it stumbles badly if the throttle is opened too fast.

The dwell is all over the shop with the light.

At least I can now pull the thing out and establish what it what.

[Pierre]

Getting the distributor apart is pretty simple. Watch out for the plastic retainer which will have gone hard and does not come on its own as a repair part. There are ways to fix involving drill and tap through the top of the spindle into the shaft and there is a parts kit for the whole distributor whose part number escapes me, but I'll post it if I find it.

Shaft drive gear may be a problem, camshaft gear might be a problem. Sounds like it's too retarded if it's hard to start and won't rev. Like you I hold out for the distributor guts!

Keep us in the loop.

Good luck

Pete

[MacMan]

More progress.

The dizzy is out and disassembled. Mechanically it appears to be fine.

Even though this is proving NOT to be a binary type electrical problem (all on or all off, permanently) I am going to replace the amplifier and leads. This morning first I had NO spark at all, then suddenly I had reasonable spark, but it stumbled on LPG when booted off idle (worse with a load in gear) but much less so on ULP. Issue is back to spark strength even when spark is present.

I am so tempted to bin the whole Lucas bizzo and go for a Scorcher. They seem to be well regarded here and overseas - even in the UK - and I need to speak to the Nunawading ignition people about a set of Magnecor leads anyhow.

[PhilipA]

Look, there is nothing wrong with the Lucas distributors, as long as the bushes do not have any play.
A scorcher probably gives a better feel because it has a more aggressive advance curve as the Lucas is very conservative. A dizzy place can regraph a Lucas for much less than $600 . Tell them to graph it same as a scorcher and it will feel the same.LOL
I suggest you spend money elsewhere if you want the car to run right. There are hundreds of thousands of cars running perfectly with Lucas dizzys as long as they have good rotors, good caps, good plugs, good leads, good electronics and good bushes.
Regards Philip A

[MacMan]

I have solved it.

It's the 5 year coil I bought from a certain spares place in Middleborough Rd, Blackburn.

Mechanically the distributor was fine, and just as a last gasp before doing something expensive, I thought I would try the original Bosch coil that was in the Disco when I bought it. The Bosch was swapped out chasing an ignition problem which turned out to be a non-genuine rotor button. It sat in the drawer ever since because the other one worked fine.

Upon swapping the no-name Shizenhousen part with the old Bosch the motor roared back into life almost as soon as the key was turned. What is even more curious is that I could return the timing back to where it was originally (about 6° advance at idle) and it ran. Swapping to the Shizenhousen coil it wouldn't start without at least 12° advance. and would die if retarded to 6°. I swapped back and forth another time and just drove it about 60km. No problem.

I know it's 5 years old, in my experience coils either work perfectly or fail utterly. This one will generate good spark when earthed to the block, but no good when feeding the distributor. No more parts from them...

[Pierre]

Good result. Ask for a refund. LOL.

Pete

[Davo]

Ah, the Blackburn mob strike again. :D

[MacMan]

Went and spoke to the helpful bods at Performance Ignition in Nunawading today and bought a new set of 7mm spiral wound leads - supposedly their lowest resistance leads. Yet to install them, but even just the old coil and new plugs has made a huge difference. I'll be heading back to get a change over vac advance unit from them.

Annoyingly, I just missed out on a used distributor with a very low buy it now on ebay last night. Too busy working!

[bee utey]

Ignition lead resistance is like shocker damping rates is to suspension. Too low and you get bounce. Too low a resistance and you may get lots of radio noise (RFI) and poor spark. If you do, and don't like it, then try the Bosch leads made for the Disco, I have found them to be very good. I used to run Top Gun leads which are very low resistance and they caused many odd running problems, especially on LPG.
Keep trying for dissy's, there are a few each month. If yours has lost the clip what sits under the rotor, its quite easy to tap a 4mm thread into the shaft, after you have dismantled the top bits, then fit a suitable screw and washer in there, saves the advance going crazy when you pull off the rotor..

Went and spoke to the helpful bods at Performance Ignition in Nunawading today and bought a new set of 7mm spiral wound leads - supposedly their lowest resistance leads. Yet to install them, but even just the old coil and new plugs has made a huge difference. I'll be heading back to get a change over vac advance unit from them.

Annoyingly, I just missed out on a used distributor with a very low buy it now on ebay last night. Too busy working!

[MacMan]

The Disco has been running superbly since all of this, but I just picked up a Scorcher dizzy at quite a reasonable price. Looking forward to swapping it over purely to make replacement parts easier to source out bush.

[MacMan]

Reviving an old thread here.

I finally set about swapping the dizzy to the "new" old scorcher last night.

Immediately, the idle seems better and there's far less float in the timing advance and retardation as the motor spins up and down. Feels like it's making a tiny bit more power down low. The bloke I bought it from threw in a near new Bosch coil to suit. I just need to tidy up the coil bracket and wiring and I'll be all rid of Lucas.

[Grumbles]

This has been a most informative thread. Well done guys.

[MacMan]

Ignition lead resistance is like shocker damping rates is to suspension. Too low and you get bounce. Too low a resistance and you may get lots of radio noise (RFI) and poor spark.

More data for this thread.

I barely ever drive on ULP and had found suddenly last month that ULP running was atrocious. Rough running generally, but surging and misfiring when coasting on gentle throttle. However LPG running was superb! Very odd I thought... Out of curiosity I tried another old coil lead which improved things somewhat. Tried yet another and things went back to normal. When I measured the impedance of the 7mm low resistance coil lead it was down below 2K Ohms. The "better but not best" measured about 5K Ohms. The best running lead measured nearly 8K. What has me confused is that LPG running is perfect, so I wonder whether the low impedance lead was starting to excite the fuel injection somewhat. The lead runs right past the MAF and close to a couple of injectors.

When I have nothing better to do I'm going to do some closer studying of what happens with different configurations of leads.

[bee utey]

More data for this thread.

I barely ever drive on ULP and had found suddenly last month that ULP running was atrocious. Rough running generally, but surging and misfiring when coasting on gentle throttle. However LPG running was superb! Very odd I thought... Out of curiosity I tried another old coil lead which improved things somewhat. Tried yet another and things went back to normal. When I measured the impedance of the 7mm low resistance coil lead it was down below 2K Ohms. The "better but not best" measured about 5K Ohms. The best running lead measured nearly 8K. What has me confused is that LPG running is perfect, so I wonder whether the low impedance lead was starting to excite the fuel injection somewhat. The lead runs right past the MAF and close to a couple of injectors.

When I have nothing better to do I'm going to do some closer studying of what happens with different configurations of leads.

Interesting, RFI affecting the ECU readings. I suggest keeping ignition leads 50mm away from each other so away from the MAF might be a good idea too. The LPG on a D1 doesn't use any part of the ECU so it wouldn't care.

I recently found a problem with a vehicle I had put Bosch leads on, the one that was arcing read 1.5K ohms and the replacement was 4.5. Ran great after that. Seems like you have to check every new part every time!

[MacMan]

50mm is a little hard to achieve when they are closer than that on the distributor terminals. I have them currently running neatly with spacers, taking care to keep #5 and #7 as far apart as possible and the coil lead away from both as much as possible.

As you point out, the fact that LPG is a "dumb" system makes me think that it must be an RF issue with the engine management.

Will keep you posted with my findings.

[bee utey]

50mm is a little hard to achieve when they are closer than that on the distributor terminals. I have them currently running neatly with spacers, taking care to keep #5 and #7 as far apart as possible and the coil lead away from both as much as possible.

As you point out, the fact that LPG is a "dumb" system makes me think that it must be an RF issue with the engine management.

Will keep you posted with my findings.
Sorry I should add 50mm is only the best spacing which happens away from the dissy. Magnetic interference between leads is cumulative with length, the most important thing is not to bundle them up tight for long lengths. Sharing a clip here and there is no big deal. Sounds like you've got that angle covered.:)

[ozscott]

Best thing I ever did was stop throwing parts at the 95 D1 and do a scorcher with Bosch coil and Bosch (australian) amp module.

Cheers

[MacMan]

OK, but which leads! Because the ones sold by Performance Ignition Services who make the Scorcher distributors are not playing so nicely on ULP!

[bee utey]

OK, but which leads! Because the ones sold by Performance Ignition Services who make the Scorcher distributors are not playing so nicely on ULP!
Bosch leads, lead set suit Disco 1 is part no. B8026i. You should be able to order it from any Bosch stockist. They are a neat and original looking lead set. No probs so far with any of these I have installed.

[LOVEMYRANGIE]

Bosch... pffft... Generic junk made to a price range.

Go for Magnecor leads

Magnecor Race Wires (http://www.magnecor.com/magnecor1/main.htm)

Magnecor Race Wires: "Faulty" wire gallery (http://www.magnecor.com/magnecor1/gallery/gallery.htm)

The Down Under Connection. Thundercords - Australian Distributors for Magnecor (http://www.magnecor.com.au/)

I would also read the article here regarding resistance measuring too.... http://www.magnecor.com/magnecor1/main.htm

Do a search on Magnecor. Lots of posts on them.

Cheers

Andrew

[MacMan]

Intertesting... I did the digging a while back and found this:

Thundercords - where to get Magnecor in Australia (http://www.magnecor.com.au/distrib.html)

I went to see them and they sold me their Scorcher cords instead of the Magnecors. I will ring them and ask about the interference problem.