JeffG Posted April 1, 2011 Share Posted April 1, 2011 Can anyone tell me what effect - if any, using either too thin or too thick oil in Stromberg 150 CD dashpots would have?ThanksJeff Link to comment Share on other sites More sharing options...
partsaver Posted April 1, 2011 Share Posted April 1, 2011 Too thin will make the carb run richer and too thick will weaken the mixture.I was told today to never use 20/50 in the dashpot but have been using that in every car of mine for many years without a problem. Link to comment Share on other sites More sharing options...
Clive Posted April 1, 2011 Share Posted April 1, 2011 In SU carbs (and as strombergs are a copy, I would say those too) thick oil richens during acceleration more than thin oil.The oil stops the dashpot rising as fast, therefore more vacuum over the jet, and more fuel sucked through. It is not so much about the needle at this point, that is when the dashpot is no longer moving up or indeed down.20/50 always seems to be a good oil to me, as it maintains a relatively even viscosity compared to many other oils. Link to comment Share on other sites More sharing options...
StagNL Posted April 1, 2011 Share Posted April 1, 2011 The way I understand it is the oil doesn't make much difference under gradual throttle application, but rather really only when one gives a bit of welly. Under harder acceleration a lighter oil will allow the metering needle to rise more quickly than a heavier oil will. Under harder acceleration one ideally wants the mixture to enrichen somewhat. This is attained by slowing down the speed that the metering needle and dashpot rises. As the engine wants to suck more stuff in, the dashpot/air valve and metering needle will rise to allow more of it all in. By keeping the air valve and needle down, the suction will automatically draw in more fuel through the jet and thus enrichen the mixture.May I stand corrected if this is not the caseSome say sewing maching oil is good, others say ordinary engine oil is good. Repair Operation Manual for the Stag with 175CDS Strombergs says engine oil if I'm not mistaken. I use 15W40, the same as the engine.JulianEdit: I see as I was distracted while typing out the above, Clive has come along and laid it out in fewer words. Link to comment Share on other sites More sharing options...
Velocita Rosso Posted April 2, 2011 Share Posted April 2, 2011 The original wkshop manual states "use engine oil SAE20 ,nothicker than SAE 30" Link to comment Share on other sites More sharing options...
Richard B Posted April 2, 2011 Share Posted April 2, 2011 Just looked in the Owners Handbook for the 2000 MkII.and it says use the same seasonal oil as the engine! Link to comment Share on other sites More sharing options...
stag_ste Posted April 7, 2011 Share Posted April 7, 2011 I have always used 10W 40 in SU's.To be honest, I would doubt that anyone could actually tell the difference reliably. Yes, thinner oil allows the dashpot to rise more quickly on throttle snaps, as the damping effect is lower, but the difference would only really be really measurable on a good dyno.BTW, I work in the powertrain development department of a large car / truck / bus manufacturer.... Link to comment Share on other sites More sharing options...
CharlieB Posted April 7, 2011 Share Posted April 7, 2011 Well if there's no oil its instantly noticeable! Link to comment Share on other sites More sharing options...
stag_ste Posted April 8, 2011 Share Posted April 8, 2011 Yes, but that isn't the question..... Link to comment Share on other sites More sharing options...
Pete Lewis Posted April 8, 2011 Share Posted April 8, 2011 easy, syringe, oil samples, stop watch , flat road, now you can remove/ add different oils and time the acceleration to see if messing about can get better results than Triumph and Zenith mangaged to achieve , its much better to believe in the manuals and go and enjoy the car Pete Link to comment Share on other sites More sharing options...
rotoflex Posted April 8, 2011 Share Posted April 8, 2011 peterhlewis wrote: syringeRelated: If you do a web search for "disposable pipettes" (or have a lab supply store nearby), pick up a couple of packages of these:http://www.etsy.com/listing/38754746/50-mini-pipettes-disposable-plasticThey are excellent for sucking or squirting small volumes of fluids from/to carb dashpots, brake reservoirs, oil into cylinder bores through spark plug holes, etc. After use, discard & don't worry about cross-contamination of brake fluid, water, oil, etc. Link to comment Share on other sites More sharing options...
Pete Lewis Posted April 9, 2011 Share Posted April 9, 2011 there goodarnt they , but dont hold much whisky Pete Link to comment Share on other sites More sharing options...
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