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On 20 Mar 2003 at 23:52, BOB2TYPE3S@aol.com wrote: > Jim wrote: > > The 311L dist gives almost 30 deg from the mech adv > >alone. That's why I like it, but that's also why you have to be careful when > >you use it with carbs. Note that the 311L vac adv gives 8-12 crankshaft degs > of adv on top of the 26-30 crankshaft degs of mech adv. > > Yes, this is what I was thinking too. It looks like the 043 905 205 would be my > better choice, as it would give with both vac and mech advance 32 -37degrees > total advance @3900 RPM, which would be less than the 38-42total from the 311L. > The 043 looks like its set up very similar to the 311, but with less total > advance, and its designed for a carb. I still prefer the 311L for several reasons. If you use it without the vacuum adv you get a good advance curve that works well with any intake system. I don't think you should use the vac adv part, but that was only a fuel economy add-on. Keep in mind that this gave the FI cars ~40 deg of crank advance, but ONLY while crusing (light load), when the engine can well tolerate that much advance. The fact that most people miss here is that the 32 deg max advance is only a FULL LOAD limit. Under light load much more advance is fine. [Unfortunately, what you get if you install one of the FI dists, with the vac advance connected, to a dual carb car is ~30 deg of advance while crusing and 30-40 deg of advance under full load, depending on rpm.] The problem with transferring a vacuum advance, any vacuum advance, from engine to engine is that you don't know when that intake system generates any particular amount of advance. The only sure bet would be to use a set of carbs with the same model vacuum can that those carbs originally came with. It is NOT sufficient to simply use a can that worked with SOME carb. In other words, different model carbs generate different amounts of vacuum under the same conditions, so using the right carb/can would give you the right amount of vac adv at the right time, but switching to another vac can might give you half as much advance, or give you the full advance much too soon. You'll never know unless you install a vacuum gauge and make a real research project out of it. If the 043 has about the same mech adv curve as the 311 I still recommend against using it with its vac advance connected. I THINK all the dual advance dists are set up the same way with the vacuum portion used just for economy while crusing. Would it be possible to find the carbs that the 043 originally came with and put 2 of them on? This probably wouldn't work either, because they were probably just for a single carb engine and wouldn't give the right vac with the flow divided in half between 2 of them. But this MIGHT just work if you could find a vac can that was twice as sensitive.... OTOH, there remains the type 1/type 3 differences between dists: They have the #1 cyl marking in different spots, and there is an oil groove in the stem which is machined in a different position because the installation orientation in the case is different. I don't know how important this might be, but VW/Bosch probably had some reason for putting this passage where they did. If the 043 is a type 4 dist, perhaps it is made just the same as the type 3 dists, so it might be a fine choice (without the vac can attached.) > Yeah, I realised that the vacuum modulator is wrong for the carbs, but > it seems to be very good, nice smooth shifts, both up and down, and at > about the specified points in the Bentley. Sounds good. Being from the US myself, I really have no idea what difference there might be in the dual carb VM. -- Jim Adney jadney@vwtype3.org Madison, WI 53711-3054 USA ------------------------------------------------------------------- List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org