Gday Terry, I seemed to have missed your followup on my post below - Id be interested in your comments on this one
Thanks Andrew > Hi Terry, > > Interesting post this. A couple of questions: > > * Given their prevalent use, have you got numbers on the S2 electronic > dizzy for comparison? > > * You mention problems at low rpm when using the single carb L18 > dizzy with sidedrafts, when the total advance has been limited to 30deg > to match L18SSS dizzy total advance. What happens when you don't > limit the total advance to 30deg, given you mention 36deg tot is usually > pretty good with 98RON fuel (just wondering because I havent played > with sidedrafts) > > * What are your recommendations with the 32/36 downdraft weber and > vacuum advance - connect it, leave it off, use a manifold vacuum > signal, use the carby/throttle signal resulting in vacuum when the > throttle is opened and no signal when its closed?? > > Thanks > Andrew > > > The only place I know of that Nissan used Bosch dizzies was Oz and they > > definitely aren't curved to suit twin sidedrafts of any sort out of the > > factory - I'd say the problem is something to do with this area. If it wont > > rev and the problem wasn't diagnosed on the Dyno runs then I can't say too > > much about the competencies of the Dyno operator - I mean other than > > recording HP at the wheels, I was told a long time ago that's what the Dyno > > was designed for. > > > A Hitachi or Mitsubishi twin carby Nissan dizzy is very different inside > > than your average Nissan factory downdraft version. Sidedrafts dizzies run > > more initial advance, both have stuff all vac advance (which defeats the > > arguments somewhat about using vac advance on most Nissan L engines and IMHO > > the use of vac advance is most effective with downdraft carbies anyway) and > > more mechanical advance but full advance isn't all that different (which is > > around 36 degrees on the average L4) > > > A factory (Hitachi) L18 single carby dizzy runs 10-12 degrees initial, 10-12 > > @ 410mm vac and 12 degrees @ 1900 rpm (24 @ 3800 crankshaft rpm) mechanical > > advance (and usually only single spring on breaker plate) which is 34-36 > > degrees (crankshaft) at 3800 rpm or WOT which will produce no vac advance > > either. > > > A twin carby L18SSS dizzy (Hitachi) (Factory Mitsubishi dizzy for the PH44 > > are different again and a tad rare today, it hasn't got a vac advance unit > > for starters and has a solid breaker plate which runs around 12-16 initial > > and 20-22 mechanical @ 3800 rpm, so 32-38 total and I've found that on 98 > > octane around 36 total advance is pretty good in most circumstances) - > > > back to L18SSS dizzy, initial advance is set to 14 degrees, 16 @ 310mm vac, > > and mechanical is 16 @ 3800 crank rpm which incidentally has dual control > > springs and split breaker plate - therefore the factory total advance is > > only 30 degrees for Hitachi sidedrafts. Problem is if you run a single carby > > dizzy with dual sidedrafts at -6 degrees initial i.e. 4 degrees to give 30 > > degrees total advance, Twin Hitachi's will spit flames through the xovers or > > filters at low rpms, very pretty but not very effective. The effective way > > to fix these problems is to recurve the dizzy. > > > regards > > Terry > > > --membersozdat------------------------------------------------------- OZDAT Mailing List Please Note:- Send (un)subscribe requests to [EMAIL PROTECTED] Send submissions to [EMAIL PROTECTED] No unauthorised redistribution of this email http://www.ozdat.com/ozdatonline/index.htm http://www.ozdat.com/ozdatonline/listindex.html http://www.mail-archive.com/[EMAIL PROTECTED]/ ---------------------------------------------------------------------
