Hi Guys, I've just purchased a 123 Bluetooth distributor and have been pondering which advance curve to set. I'm running a type 4 with a 1911cc top end and single progressive Webber carb... The options are endless, do I base the curve and vac advance on a 034, 205, or 009 with added vacuum advance? I know that there's a load of other distributors and associated curves to choose from. I wanted a vac advance to help with the flat spot from idle. My head is starting to hurt. 123 ignition will send me the correct advance curve for whatever distributor I choose... Thanks in "advance" Chris
i have the 123 with pre-sets - tried 0 (default / one-size-fits-all) and 9 which according to the manual is the closest match to the p/n on my original distributor. Runs fine on both, cant' really tell the difference tbh. Winnie the Poo (update: seals, h./ex, afr) | Page 16 | The Late Bay
You get rid of the flat spot by throwing the carburettor very hard against a wall.. Without heat risers and hot air, you are going to fail unless you dont mind ridiculously poor MPG and smoke coming out the back from the over rich mixture. Should have saved the money on the 123 and used it to buy into dual carburettors. And fit a fuel shutoff solenoid for when the damn carburettor leaks petrol into the engine too. From idle, the flat spot is that the petrol from the accelerator pump just sits in the manifold as it hits the cold walls of the manifold. So the engine does not pick up because it is running very lean at that point. Playing with advance curves doesnt change the problem. Theres also a second flat spot that you get on the transition from primary to secondary carburettor venturis. This one is because the air speed drops in the venturi, and there is not a lot of extra fuel at the same time - the engine goes lean momentarily, felt as a lurch around 60mph if you floor it. Again the distributor advance curve doesnt cure this one.
No they didn’t, I’ve recently had a new Bosch blue coil though. I think I should have rephrased my original question to what is the best original stock distributor… All I wanted to know was which was best then I could emulate that advance curve.
No, fortunately my Weber progressive is happily installed on a T1 with stock heat risers and hot air feed through the air cleaner. So I only get some slight hesitation on a coldish engine after about 3 miles, where the choke has started coming off but the air intake and heat risers are still quite cold, and again a brief "blip" from cruising at 60-65mph on the flat if I stamp on the accelerator.
If you go over on The Samba, there are a collection of distributor curves based on data I scanned in from a circa 1974 engine service manual. https://www.thesamba.com/vw/forum/viewtopic.php?t=617242&highlight=
This is a fair question, but buying a 123 will not improve the flat spot caused by the carburettor installation, for the other technical reasons given, unfortunately.
This is what Aircooled.net has to say: ‘Centermount Progressives NEED intake heat, and lots of it. This is why a progressive on a Type 4 WILL NOT WORK. It’s so bad and unfixable, we do not even sell the kits that are available. The intake volume is too large, and there is no easy way to get the intake manifold and runners heated up. It will not work well, please do not ask, because the answer is “get dual carbs”.’ Nobody can tell you what the best curve is because VW never fitted a single progressive to a Type 4 engine, just copy any of the SVDA curves that Mike posted on the Samba and tune it from there – that’s presumably why you bought a tuneable distributor.
I have a dual Weber 34 ict full kit for sale which would suit your engine & cure your flat spot issue. Definitely give you a vast improvement over the single progressive. Pound for pound they will make a bigger difference than a 123 distributor.
I was under the impression that the lack of vacuum advance on the 009 that I had fitted on my bus was contributing to the flat spot?....
I'm having a few issues at the moment, I've set it up at 7.5⁰ at idle and 28⁰ at 3400rpm but it's running rough and I have an occasional missfire.... Can you pm me with what you want for the carbs please?
It would if you had a single Solex on say a 1600, but likely your problems are caused by that horrible carb.
