Strombergs to Su’s distributor

[Grant]

Good morning all .

I’m just converting my US series 2 from strombergs to Su s, do I need to change the distributor as well?
Or is there a thread already
I have tried searching this on here but no luck ,

Thank you in advance

Grant

[Tom W]

The advance curve for US emission spec cars is different to that for SU equipped cars. You can fit a new distributor to the correct spec, or have the original rebuilt to give it the right advance curve. Alternatively, you could fit a programmable distributor like a 123 Tune, and draw the appropriate advance curve on the software.

[Grant]

Hi Tom

Thank you for your reply , I’ve just started to read up on these , has anybody fitted one of these ? Or the blue tooth version?
Is there any benefit from the Bluetooth are they a lot easier or more complicated? This is my first delv in to distributors as you can tell.

Much appreciated

Grant

[mgcjag]

Hi Grant...also look at compression ratio...US spec are usually different to UK you just need you be aware...plenty of info on here if you search for 123......some have fitted the Tune bluetooth version.....im sure they will chip in soon...Steve

[Grant]

Hi Steve

I’ve just stumbled across all the 123 stuff it seems very interesting but I’ve not seen anything about the compression differences,
Has anybody done this to a US car ?
Does that make a difference which 123 distributor I choose?

Thank you all again

Grant

[Tom W]

My car is ex US. It has a 9:1 compression ratio. I have the JAG123 distributor. It is pre-programmes with 16 curves, which are supposed to be tailored to the Jag XK engine. None of them seem to match the curve for a UK spec S2 as it’s described in the workshop manual though. Not a problem for me though, as my car has Webers, so the standard curve isn’t appropriate anyway.

The 123 tune can be programmed to give any curve. It comes with a lead to plug into a computer. The Bluetooth version does the same thing, but can be programmed remotely by an app on your phone. This is probably the best bet, and if I were buying one now it’s what I’d go for. It wasn’t available when I bought my car, and it came with the 123JAG anyway.

You can use the data in the workshop manual to create the factory curve in the 123Tune. Or, a decent rolling road should be able to create a bespoke curve that optimises the performance of your engine.

[johnetype]

Yes, you do need to change the distributor to the one fitted to UK spec. cars at the time with vacuum advance.

That leaves you with a lot of options from fitting a secondhand UK spec. Lucas distributor to having your current distributor rebuilt to UK spec. by the likes of Distributor Doctor. Probably the cheapest "drop-in" option would be a complete new distributor from Simon BBC (Powerspark) circa £80 including electronic ignition to the range of programmable distributors offered by 123.

If you do fit a distributor with electronic ignition you'll get into the "will my rev counter continue to work debate". Your rev counter will continue to work without modification as long as you wire up the new distributor the correct way which is not necessarily as per the distributor's instructions. PM me for details if you like.

Depending on the age of your car you may have a ballasted coil. If you do, and you fit a distributor with electronic ignition it would be best to remove your current coil and ballast resistor and replace them with a new coil matched to your new distributor.

[Tom W]

I would want to find out with the “Drop In” option from Simon BBC, what the curve actually is. There doesn’t appear to be any choice of curve, just a statement that says it’s specific to 6 cylinder vehicles. Any 6 cylinder distributor is specific to 6 cylinder vehicles, by virtue of having 6 HT lead connections. The curve you need is completely independent of the number of cylinders and is more related to engine design, in particular cylinder head design.

Does anyone have one of these Simon BBC distributors, do you get any documentation to tell you what the curve is?

[Grant]

Hi Tom and John

thank you both for your answers , I will have a read up today but I must admit I’m leaning towards the Bluetooth 123 as this may leave it easier today and to maintain in the future?

Thanks again

Grant
Ps is sng Barrett the best place to get it ?

[johnetype]

Does anyone have one of these Simon BBC distributors, do you get any documentation to tell you what the curve is?

Tom, I bought one of these distributors as a "cheap, get me going" option and it didn't come with any documentation on what the curve is. That said, it works very well, the engine runs very smoothly with no pinking and I'm very pleased with it. With the vacuum advance connected I get a significant improvement in MPG and a cooler running car.

[johnetype]

thank you both for your answers , I will have a read up today but I must admit I’m leaning towards the Bluetooth 123 as this may leave it easier today and to maintain in the future?

Grant there is no "maintain in the future" with an electronic distributor, you fit it, set the timing and enjoy driving the car

There's been a lot of discussion on this forum on the merits of the flexibility of the 123 versus the potential unreliability of the extra electronic complexity versus the simplicity of the original points system. I suggest you read the threads on the 123 and decide for yourself.

[mgcjag]

Hi Grant...its the same product wherever you get it........re compression look at your engine number....it will end in 8 0r 9.....8:1 or 9:1

[Grant]

Hi John

That’s what I had hoped in others words go for the more expensive now and it will save me time and money on maintaining and tune the old style.
Most videos I’ve seen seem to say they give really nice smooth power .
So I think that’s the way I will go .

Thanks again

[Grant]

Hi Steve

that’s great thank you I was wondering how to work that out .

Thank you

Grant

[Grant]

Hi Steve

So it seems I have a 9:1 as my engine number is 7R 6393-9
And it has no vacuum pipe at the moment and an electric points system inside the distributor like an accuspark system.
I’ve not seen a vacuum mentioned on the 123 one but I will ask sng Barrett tomorrow as I order.

Thanks again everyone all advise is always great fully received.

Grant

[Tom W]

I think the 123 is available both with and without vacuum. You want the one with the vacuum signal. It doesn’t have a vacuum canister in the conventional sense, but instead a little electronic sensor. Theres a little stub on the side to connect the vacuum to and electronics inside sort out the advance.

[Grant]

Hi Tom

Excuse my ignorance but I want the one with the vacuum even though the current one does not ?
Is that because of the change to SU carbs ?

Thanks

Grant

[Tom W]

The original distributor for SU specced engines used vacuum advance. The SU carbs will have a port of the vacuum take off, which you’ll have to plug if you fit a distributor without vacuum advance. It’s worth having, vacuum advance improves part throttle efficiency.

Some stromberg equipped US cars have a vacuum canister. There were several different versions of the Stromberg set up to meet the US emission laws.

[mgcjag]

Hi Grant...not sure if your asking this......the 123 tune + has a vacume nipple so you can connect from SUs to it

[Grant]

Hi Tom and Steve

Sorry for the slow reply but for some reason I’m not getting the notifications to let me know anyone has replied.
Thank you very much
The 123+ tune has arrived now so I’m sure I will figure it out .
One last question before I do it all at once has anybody fitted the 123 with strombergs?
I have not opened the box yet but was wondering if anyone knew which setting to go with ?

I’m going to have a go at it tomorrow and am planning to film it and may post my workings to help the next guy . :-)

I will let you know

Thanks again
Everyone for your in put and help

Grant