Distributor Options

For all those wiring gremlins we love, this is the place to discuss them.

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Brisvegas
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Distributor Options

Post by Brisvegas »

Hello All
I wondered if I can get some feedback from some of the more technically savvy people in the group.
I have a 87 model year SA with 54k miles that seems to be exactly as it left the factory with original carbs,coil and distributor all in place.
It runs OK , takes about 3 cranks to get going , is lumpy on initial tick over, and accelerates OK.
When you come back from a run it sounds great.
I don't want to do track days or spend thousands on high tech gizmos , I just want a car that starts well, doesn't sound like a diesel on start up and accelerates well.
This year I have decided to look at modernising the ignition set up but not going as far as fuel injection etc etc.
I have no technical ability myself . Also looking to be able to go back to original set up if required/ desired.
I am planning on getting the carbs rebuilt, new HT leads etc and while they were out I thought I would replace the dizzy and coil with something more modern and I am looking at 3 options.

123 ignition - I like the idea of the blue tooth version but quite expensive in Australia

Pertronix seem to have recently released a British 4 cylinder dizzy with an Ignitor 3 unit and a 45000 volt coil. This means that I can have a unit that has an in built rev limiter and makes the AB 14 and rev limiter units redundant. Both potential sources of problems that are difficult to replace here.

Accuspark more basic but much cheaper than the 2 options above

Also interested in a thread I read about MSD ignition but don't know anything about it.

What are your thoughts and likely advantages/ pitfalls ?

Thanks

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Lotus-e-Clan
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Re: Distributor Options

Post by Lotus-e-Clan »

Is your vacuum-based engine management system working to spec? Running lumpy when cold/going well when hot can be caused by vacuum leaks or incorrect hose connections to thermal valves etc.

I'm assuming the 87MY SA has the vacuum based engine management system

I can only be sure about 89MY onwards. Here's a link to a diagnosis chart which might help.

The Image below is a Lo-fi screen shot of page 1. The PDF Pages are LARGE (A3 sized - it's a complicated table!) so printing might be difficult.... but it's easy to view on a good PC/Laptop screen using appropriate magnification.

Image

Here is the link to the PDF on 1Drive - you can download the PDF from there: Best viewed off-line in a proper PDF viewer.
I realise you asked specifically about dizzy replacement - just not sure why your focus is on a dizzy replacement? Have you been told it is worn out?
Last edited by Lotus-e-Clan on Thu Feb 08, 2018 13:02, edited 1 time in total.
Peter K

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Re: Distributor Options

Post by AndyC »

I'm with Peter there.
From your description, it would appear there's a fault / inaccurate setting, it's not normal for a car to be lumpy if it's tuned correctly.

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Re: Distributor Options

Post by amarshall »

I'd be looking to the green thermal valve and hoses associated with it, I think.
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Re: Distributor Options

Post by Phantasm »

I replaced all of my vac hoses and then shortly thereafter replaced my dizzy cap and rotor. The cap and rotor had a bigger impact on smoothing out my engine. They are very cheap to replace and might be worth doing that before going all in on a new setup??
Not discounting changing out the vac lines mind you, just my experience.
-Bill
1991-92ish Lotus Excel SE Silk Red
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richardw
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Re: Distributor Options

Post by richardw »

Brisvegas wrote:Hello All
I wondered if I can get some feedback from some of the more technically savvy people in the group.
I have a 87 model year SA with 54k miles that seems to be exactly as it left the factory with original carbs,coil and distributor all in place.
It runs OK , takes about 3 cranks to get going , is lumpy on initial tick over, and accelerates OK.
When you come back from a run it sounds great.
I don't want to do track days or spend thousands on high tech gizmos , I just want a car that starts well, doesn't sound like a diesel on start up and accelerates well.
This year I have decided to look at modernising the ignition set up but not going as far as fuel injection etc etc.
I have no technical ability myself . Also looking to be able to go back to original set up if required/ desired.
I am planning on getting the carbs rebuilt, new HT leads etc and while they were out I thought I would replace the dizzy and coil with something more modern and I am looking at 3 options.

123 ignition - I like the idea of the blue tooth version but quite expensive in Australia

Pertronix seem to have recently released a British 4 cylinder dizzy with an Ignitor 3 unit and a 45000 volt coil. This means that I can have a unit that has an in built rev limiter and makes the AB 14 and rev limiter units redundant. Both potential sources of problems that are difficult to replace here.

Accuspark more basic but much cheaper than the 2 options above

Also interested in a thread I read about MSD ignition but don't know anything about it.

What are your thoughts and likely advantages/ pitfalls ?

Thanks
Hi there,

You basically have two choices when considering electronic ignition systems:

1. 'Passive' systems that essentially replace the points in a distributor, but still depend on the dizzy's mechanical and vacuum advance for timing. These systems are simple, inexpensive and essentially 'fit and forget.' Great value.

2. 'Active' systems that take over the dizzy's timing functions, enabling timing to be mapped against revs and load/throttle position, essentially combining the mechanical and vacuum advance functions of the distributor.

The 'Active' systems will be attractive to those seeking to have more control over performance, often by tuning the engine beyond the 'safe' limits originally used by the manufacturer. You can quite easily replicate the distributor timing profile in these systems, but if that's all you want to do, what's the point (excuse the pun!)? You may need to use a rolling road to optimise the performance of these systems.

Both types deliver stronger and more reliable sparking, enabling wider plug gaps to be used for better ignition. However, most (I think) 9xx engines also used an ignition amplifier for this purpose - the weak spot remaining the contact breaker points themselves.

Finally, some 'active' systems allow you to do away with the conventional coil altogether and use a coilpack instead, for better performance and reliability.

I hope this is helpful!

Richard
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Lotus-e-Clan
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Re: Distributor Options

Post by Lotus-e-Clan »

The 912 engine has used contactless ignition from the outset - ie no points to worry about. But ignition 'scatter' which isn't 100% absent even in a new dizzy, will get worse as the spindle begins to wobble more on worn bushes/bearings.

One major advantage of fully mapped ignition versus a dizzy-based 123 system which folk seem to over look is the advantage of the deletion of the dizzy cap and rotor arm (and therefore the HT air gap) with fully mapped. With fully mapped ignition the coil(s) are hard wired to the plugs - therefore no dizzy cap issues (no air gaps for sparks to jump).

Having at least two coils with mapped ignition increases the 'Dwell angle ' which means the coils can recharge more fully between discharges at VERY high rpm. As a lot of Excel owners rarely rev beyond 5K rpm Dwell Angle isn't a big issue anyway ..it is though if you fit racier cams and shift the powerband higher. The most efficient systems will have one coil per plug as per moderns

As far as I know with the 123 system you are stuck with one single coil and a dizzy cap with a rotor arm to distribute the HT across an air gap. .. A real weak point as Phantasm explained in a previous post, and no better than the OE dizzy in that regard. Fully mapped is a whole step better - but money is usually the deciding factor to be fair.
Peter K

Brisvegas
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Re: Distributor Options

Post by Brisvegas »

The local specialist replaced the vacuum tubes last year and recommended a carb rebuild .

So to recap so far, the consensus is follow the flow chart and make sure the standard set up is correct .
In particular make sure thermal valves are working .
Then replace the relatively inexpensive options like coil ,cap , rotor ,leads etc and hope that this fixes or improves any issues.
At that point if still not happy then look at the distributor or mapped ignition etc

I was hoping that by turning up at the workshop for the carb rebuild with a full set of modern parts including the distributor that it would cut to the chase and help the carb set up rather than paying to redo the same work at a later date if the step by step approach doesn't fix the issues.

Brisvegas
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Re: Distributor Options

Post by Brisvegas »

Hello Peter
Thanks for the fault finding chart .Excellent work.
It has dropped a little cooler in Brisbane so got a chance to spend some time on the car today with the vacuum hoses and trying to confirm the valves worked and the tubing was on the correct ports.
On the green valve tubes were correct and removing the red black one dropped revs from 1100 to 950 .
Removing dizzy tube seemed to cause slight misfire when accelerated above 4000 rpm.

I don't have a throttle solenoid as it is an SA.

Brown valve is really hard to see but the only bit I can see looks dark green on the end farthest from the thread,rather than brown.Tubing seemed correctly attached and removing tube from rear carb didn't seem to affect progression when revving harder..

I replaced crankcase breather with a new one from SJS 6 months ago as the original didn't have any baffle discs inside it.

Regards
Mark

Brisvegas
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Distributor Options

Post by Brisvegas »

I have worked through the fault finding sheet and everything seems to be working fine .
Particularly the green valve and associated tubes.
Peter you have me interested in mapped ignition and I would like to look at the possibility of fitting a basic system .
I would prefer to leave original set up in place just in case of emergencies and originality if possible.
If not I would just keep the bits just in case.
There seems to be a lot of brands and a wide range of prices and options.
Aldon seem to do a locked dizzy based system that becomes the trigger wheel.
It is the addition of the trigger wheel and sensor that worries me the most so would this option avoid the need for extra brackets and adding bits to the front of the engine ?
Megajolt looks interesting .

Are there any systems on the market since you did your set up that would be an easy entry into modernising the ignition without ripping too much apart.

I am trying to do the research before I visit the UK at the end of May so if needs be I can purchase some stuff over there and bring it back with me .

Regards
Mark

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Re: Distributor Options

Post by lambert.john »

I have a query for those with a Pertronix ignition system.
Having found significant wear in the bearing of the original distributor in my SA, my mechanic suggested that, whilst attending to this, I should upgrade to a superior electronic system and recommended Pertronix. This has now been done, and (early days) seems to be working okay. However, he replaced my lightly used iridium NGK BPR7EIX spark plugs with a set of basic NGK BP6ES plugs on the grounds that the new system did not require the resistance of the BPR plugs. I have read the blurb that comes with the new system and it does, indeed, talk about the need to be aware of the "external resistance" in the overall set-up (frankly all a little beyond me).
My basic question is, if you have the Pertronix system, what plugs do you use? I'd be grateful for your comments.
John L.

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Hawaiis0
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Re: Distributor Options

Post by Hawaiis0 »

Excel SA is a spec 10 set up so should have BPR7ES
Nothing is fool proof. Fools are clever!

lambert.john
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Re: Distributor Options

Post by lambert.john »

Thanks for the reply, Stuart. Are you using the Pertronix system; have you had any issues with it?
John L.

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Re: Distributor Options

Post by Hawaiis0 »

At the moment with engine out and a new HC 2.5 going in, fuel injection is looming. I am unsure on my ignition choice at the moment so jury is out
Nothing is fool proof. Fools are clever!

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