123 Ignition

Hi - I promised to report on this.. For them what don't know it's on a 1966 E-Type, 9:1 pistons (Brit, not European or American spec). For them what knows me of old I apologise for being boring.

First impression - absolutely excellent. Pulls strongly from 700rpm to

5,000 rpm (at which point the engine goes bang). It is, subjectively, far more smooth throughout the rev range - and it wasn't exactly a rough old nail before.

Now the downsides. Under specific conditions, full throttle in third or fourth, between 3,000 and 3,500 there is a very brief misfire followed by two or three backfires. Doesn't happen if you are accelerating moderately gently, only if you are balls to the wall.

Then there is the issue of which version you buy. I've gone for the general "six" version. There is a specific version for the E, prefixed JAG. But this appears to have been designed by a Jaguar racer about seven years ago. Fuels have changed since then, and anyway it's a road car, not a racer.

And the matter of the curve you set. 16 choices. Factory recommended is 4; if it pinks, try 5. Other people have given opinions ranging from 9 to A. And one person had the same problem with the misfire, and gave up and went back to points. Problem is that you have to take the whole unit out to alter the curve - not an easy job on the E - it would have been good if there was a simple vernier on the side, a la distributor.

Also, it's running hot. Even in this horrible weather the Kenlowe is on 80% of the time, whereas it should only cut in if you have been stationary for several minutes.

Obvious points have been checked: fuel supply OK (new pump just fitted), coil OK, plugs OK, HT leads OK.

I emphasize this is only a preliminary report, less than 100 miles due to the failure of the fuel pump.

Next step is probably a rolling road test. Anybody know one within easy reach of Surrey/Sussex border, or possibly Surrey/Middlesex? Must be one which understands elderly cars and allows the owner to fiddle about under the bonnet while the car is running - my local one won't even let you in due to "elf n safety".

Will report further.

Geoff MacK

Reply to
Geoff Mackenzie
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Did think it a bit crude. The obvious way is to do it in software and programme via some form of external controller.

The cheap and cheerful Jaycar unit uses a dedicated controller on a parallel cable which you simply disconnect after use. So rather fiddly to use since you have multiple function buttons.

The MegaSquirt hooks up to a PC via a serial port. Doesn't need a fancy PC - anything that will run Win95 onwards. I've actually got the MegaSquirt up and running on the SD1 - but only doing the fuelling for the minute. Once that's near enough - and it's looking promising - I'll swap over the ignition to it too.

Nothing to stop you using a Jaycar unit to alter the curve from the 123, though. Although the timing would have to be vastly out to cause a misfire. Sure it's not simply a spark problem? These high output devices often cause tracking on a system not designed for so much energy - or even break down the plug leads.

Reply to
Dave Plowman (News)

That is a possibility. I knew an electronics student who made his own electronic unit, but it ran at a voltage that was difficult to keep inside the plug leads. So he had to keep the leads scrupulously clean otherwise the sparks ran down the dust on the outside of the leads and jumped across to the block to earth. Lift the bonnet on a dark and misty night and there was St Elmo's fire running across the top of the engine. In the end, he encased each plug lead in a plastic tube!

But in your case, I wonder if the timing is quite right? You have a combination of vacuum and centrifugal advance curves in a conventional dizzy set-up and I wonder if you have got the 123 reacting correctly to revs and vacuum? It could explain why you are running hot.

I would also try another set of plugs. It is not unknown for there to be an occasional iffy one, even if it is brand new.

Jim

Reply to
Jim Warren

Just an outside-the-box thought here - land rover 2.25 engines with ducellier distributors used to suffer the exact same thing, caused by a bad earth between the fixed and moving parts inside the distributor. I wonder if there's some sort of earthing issue going on?

To be honest, pump fuels haven't really changed much since the introduction of unleaded petrol way back when.

Running hot is a classic symptom of retarded timing, even a change of 5 degrees (on a rover V8 engine) produces a considerable increase in running temp. Ally head engines seem to be more prone to this than cast iron ones.

Sorry, I don't even know of any in the North of Scotland! Badger.

Reply to
Badger

I think Bob Henderson, formerly MPG&H Conversions, has one. He used to be based in Surrey, but has for many years been on the Isle of Skye. Hope this helps....

Geoff MacK

Reply to
Geoff Mackenzie

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