123 Ignition distributor

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Joe™
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123 Ignition distributor

#1 Post by Joe™ » Wed Oct 18, 2017 9:32 am

Hi all,

Does anyone have any experience with the 123 Ignition distributors in our cars?

I have already purchased one but before I rip out the existing setup I have some questions regarding installation and curve choice.

It's also an opportunity for me to fit the vacuum advance which for some reason my car has always been without - I assume the hose needs to be attached to manifold and not somewhere on the carbs?

Thanks.

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Alec
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Re: 123 Ignition distributor

#2 Post by Alec » Thu Oct 19, 2017 6:45 pm

Hello Joe,

unless you go with the lap top programmable 123 I would suggest getting the original distributor overhauled and set up to the original curve. The 123 with sixteen curves is unlikely to be correct for your engine. The only engine that did not have a vacuum advance was the P.I. of certain years. If yours is not one of those then the distributor should have a vacuum advance and is connected to the carburettor, not the manifold.

Let us know what engine you have.

Alec
0465

MK1.5 2.5 P.I.
Jaguar MK 2 (Long term restoration.)
Hymer 564 Motorhome.
Jaguar X Type Estate 2.5

Joe™
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Re: 123 Ignition distributor

#3 Post by Joe™ » Sat Oct 21, 2017 1:10 pm

Thanks for your reply Alec.

The car is a bit of a mash up, it has a mk2 2.5 Pi block & head (high compression) but has the twin HS6 carbs as it is a TC originally.

The reason for my query is because it seems from the documentation supplied with the 123 that the most gentle advance setting results in a max advance of 27 degrees at 4200 rpm (15 degrees @ 2000 rpm). I only drive the car on the street so it does not get revved excessively aside from the occasional stretching of the legs. I have tried to find the max advance figures from the factory but am having difficulty finding an accurate source. I suspect that 27 degrees is far too much but wouldn’t mind some input from others better informed than me.

I would like to run the 123 if possible, they get very good write ups and several friends (albeit ones with German cars!) have had great experiences with the product.

With regards to the vacuum advance, this has never been connected as long as I’ve owned the car. I’ll have to look and if there’s a nipple on the carbs.

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Re: 123 Ignition distributor

#4 Post by Alec » Sat Oct 21, 2017 2:24 pm

Hello Joe,

I don't have my manuals to hand, but my Mk1 manual I have in the house which also does the early Mk2 2000 has that model with 22 to 26 degrees mechanical maximum (with another 22 degrees vacuum but that will be at mid range. 6 to 8 degrees mechanical at 1800 rom so your 15 at 2000 may be too much.

From what you say it sounds lik eyou have a late T.C. engine with slightly higher compression ratio? I'll have a look when I go out and see what specification distributor is fitted to that engine? Forgive me if I'm telling you something you already know but the mixture is set by the factory to run weak at cruising speed and the vacuum advance provides the extra advance the engine needs to run smoothly, so it is a good idea to get it working.

I must admit to not being a fan of these 123 distributors as for the money you can have a refurbished, perfoming as new distributor with the correct curve. I had mine done by a company called 'Distributor Doctor'

Alec
0465

MK1.5 2.5 P.I.
Jaguar MK 2 (Long term restoration.)
Hymer 564 Motorhome.
Jaguar X Type Estate 2.5

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Re: 123 Ignition distributor

#5 Post by Joe™ » Sat Oct 21, 2017 11:13 pm

No it’s a Pi engine (number starts with MG), so I appreciate im in slightly uncharted territory!

The car currently has a 25d fitted to it and does not run particularly well hence my interest in the 123.

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Re: 123 Ignition distributor

#6 Post by Alec » Sun Oct 22, 2017 7:44 am

Hello Joe,

OK, so the carburettors are probably not quite right either? While many P.I.s were changed over to carburettors I don't know what distributor or needles are best suited for that engine.
Ideally a rolling road session is the best way to get the best out of your car, otherwise it is trial and error and the priority is to get the carburettors set up (if they are not already?) as this affects the best timing. P.I. engines have less of maximum advance than the carburettor cars (about 20 degrees + or - 2 degrees). Bear in mind the static timing which may be different between P.I. and carburettor which is added to the mechanical advance.

Have you thought of changing to injection?

Alec
0465

MK1.5 2.5 P.I.
Jaguar MK 2 (Long term restoration.)
Hymer 564 Motorhome.
Jaguar X Type Estate 2.5

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Re: 123 Ignition distributor

#7 Post by johnnydog » Sun Oct 22, 2017 10:59 pm

Alec wrote:
Sun Oct 22, 2017 7:44 am
Hello Joe,

OK, so the carburettors are probably not quite right either? While many P.I.s were changed over to carburettors I don't know what distributor or needles are best suited for that engine.

Alec
If I am not mistaken, Chris Witor recommends fitting BFZ needles to a 2.5 PI (originally fitted with fuel injection) now running on SU HS6's.
Register Member no. 1596

1967 Mk1 2000 in Gunmetal Grey
1969 Mk1 2000 in Royal Blue
1970 Mk2 2000 in Valencia Blue
1972 Mk2 2.5 PI in Triumph White
1973 Mk2 2.5 PI in Sienna Brown
1976 Mk2 2500S in Carmine Red

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Re: 123 Ignition distributor

#8 Post by Joe™ » Tue Oct 24, 2017 10:12 am

johnnydog wrote:
Sun Oct 22, 2017 10:59 pm
Alec wrote:
Sun Oct 22, 2017 7:44 am
Hello Joe,

OK, so the carburettors are probably not quite right either? While many P.I.s were changed over to carburettors I don't know what distributor or needles are best suited for that engine.

Alec
If I am not mistaken, Chris Witor recommends fitting BFZ needles to a 2.5 PI (originally fitted with fuel injection) now running on SU HS6's.
He does, I already have some BFZ needles in my HS6s on his recommendation!

Though admittedly, even with the 'correct' needles, the P.I cam doesn't like the carbs too much at idle so isn't the smoothest.

Either way it looks like the 123 isn't going to work. I will have to see if i can return it. Shame.

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Re: 123 Ignition distributor

#9 Post by Joe™ » Tue Oct 24, 2017 10:22 am

Alec wrote:
Sat Oct 21, 2017 2:24 pm

I don't have my manuals to hand, but my Mk1 manual I have in the house which also does the early Mk2 2000 has that model with 22 to 26 degrees mechanical maximum (with another 22 degrees vacuum but that will be at mid range. 6 to 8 degrees mechanical at 1800 rom so your 15 at 2000 may be too much.
Correct me if i'm wrong but that would equal a TOTAL advance of 44-48 degrees? I reached out to 123 and found that the 27 degrees I spoke about earlier is 17 degrees mechanical at 4200 + 10 degrees of vacuum advance.

The complete chart, explained better, can be found here http://www.123ignition.nl/product.phtml?id=32

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Re: 123 Ignition distributor

#10 Post by Alec » Tue Oct 24, 2017 2:25 pm

Hello Jpoe,

no it doesn't work like that the vacuum module has a minimum and maximum vacuum figure and out of that range there is no vacuum advance. So at peak revs you'll have little or no vacuum so no advance. It only operates in mid range and with part throttle.

The 123 figures only really give you about four choices once you pick the correct maximum advance so not a lot of scope.

Alec
0465

MK1.5 2.5 P.I.
Jaguar MK 2 (Long term restoration.)
Hymer 564 Motorhome.
Jaguar X Type Estate 2.5

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