PeaTear Posted May 29, 2018 Report Share Posted May 29, 2018 Does anyone know what the brown doodahs on the bottom of the carb pistons are for. On mine the rear one is quite shorter than the front, so the front has a gap between the carb body and the piston and the rear doesn't. Is this gap crucial or should it be closed? Thanks in advance Link to comment Share on other sites More sharing options...
Anglefire Posted May 29, 2018 Report Share Posted May 29, 2018 They should be straight for a start. there is a screw on the side of the cast part which allows the needles to be removed. Once that is done there is a letter/number reference on the upper barrel of the needle which should be the same for both. You may be able to straighten the one. If not get a new pair so the wear if any is the same. When fitting make sure they are fitted with the Collar flush to the barrel Link to comment Share on other sites More sharing options...
PeaTear Posted May 29, 2018 Author Report Share Posted May 29, 2018 Haha. Sorry didn't mean the needles although I now see the wonky one. Easier to see in the first pic, bottom left hand near the edge of the piston, there is a little thingy sticking out, that's what I'm talking about Link to comment Share on other sites More sharing options...
Mad4classics Posted May 30, 2018 Report Share Posted May 30, 2018 The plastic piston stop is there to stop the piston resting directly on the bridge. Fuel discoloration makes it brown. Might be available as a seperate part, worth a call to Burlen Ltd to find out. David Link to comment Share on other sites More sharing options...
PeaTear Posted May 30, 2018 Author Report Share Posted May 30, 2018 Thanks David. Dropped them an email Link to comment Share on other sites More sharing options...
Paulfc Posted May 30, 2018 Report Share Posted May 30, 2018 Hi, what carb make and type is it? Link to comment Share on other sites More sharing options...
Anglefire Posted May 30, 2018 Report Share Posted May 30, 2018 Su carb hs2. Link to comment Share on other sites More sharing options...
Mad4classics Posted May 30, 2018 Report Share Posted May 30, 2018 With HS2 and trying to judge the standoff those stops would give you from the pictures; I suspect the larger stop is incorrect - but it's difficult to judge from pictures. The stop is not very tall. If the piston is held off too far it will upset adjustment. David Link to comment Share on other sites More sharing options...
Pete Lewis Posted May 30, 2018 Report Share Posted May 30, 2018 The piston stop is there to ensure the throat is not closed completely or you would never start the car It must have air flow over the bridge and this drags the fuel from the jet, so the stop maintans a small gap to allow air flow for when you Crank it up, once its fired the piston rises to its idle posistion Pete Link to comment Share on other sites More sharing options...
PeaTear Posted May 30, 2018 Author Report Share Posted May 30, 2018 Thanks guys. The gap on the front carb is about 1mm and I can't remember if there is any gap on the rear. To me the front does look very high and I can't find any reference to correct gap height on my searches. I'll load a picture later showing the difference hoping those that are more knowledgeable than me could let me know what is correct Link to comment Share on other sites More sharing options...
Pete Lewis Posted May 30, 2018 Report Share Posted May 30, 2018 you need to ask Burlen fuel systems about these little stops , some are just a push in plastic plug some are part of the piston there is no reference to them in any manuals or spares lists for sure both should be the same , and all needle holders must be level with the base of the piston. Pete Link to comment Share on other sites More sharing options...
PeaTear Posted May 30, 2018 Author Report Share Posted May 30, 2018 No problem Pete. I'll get on to them Thanks Link to comment Share on other sites More sharing options...
Mad4classics Posted May 30, 2018 Report Share Posted May 30, 2018 Just for reference, the SU Carburetter High -Performance Manual gives the minimum air gap as about 0.010" to 0.015". On this new - unused fixed needle HS2 piston I keep as a spare, the height of the plastic stop measures 0.013". David - Link to comment Share on other sites More sharing options...
Pete Lewis Posted May 30, 2018 Report Share Posted May 30, 2018 David glad you found it I scanned through that but didnt find the clue Its amazing how many times the one little snippet you need is always lost hidden or just missing Pete Link to comment Share on other sites More sharing options...
PeaTear Posted June 1, 2018 Author Report Share Posted June 1, 2018 burlen do sell these. They are called damper pins Part Number: AUD 2435 Link to comment Share on other sites More sharing options...
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