Citroen Specials Club - the club for all lightweight cyclecars

Hi...Just fitted a Blackjack SU conversion to my project but can't get it to run properly since I took carb apart and cleaned it all....should have left it alone!! Seems to be very rich, difficult to start and very lumpy. Don't know the carb identity and would be grateful if anyone could suggest how I start . I've tried moving needle up and down ( as far as I dare) and played about with the adjusting screw which, IF my reasoning is correct, weakens the mixture the more you screw it in. Needle Jet cuts off Ok so......I'm stumped as the SU is a new animal to me but don't want to go down the old carb route .

Assuming that you have the HIF type of SU with the float chamber underneath, turning the screw in (clockwise) makes the mixture richer, out is weaker.
http://www.v8register.net/FilesV8WN/SUb ... vicing.pdf
Link to a useful explanation.
Good luck.

Ron, you don't say which SU you have but I assume that as you mention a mixture screw it's an HIF.
As far as I'm aware, all SUs have the needle at a fixed height. It is not intended to be adjustable.
To make the carb suitable for a given engine the needle profile needs to be changed.
Almost any needle should enable you to get the engine to run at low revs but the profile will potentially cause mixture problems as the revs rise.
I think I'm right in saying that screwing in the mixture screw gives a richer mixture.
A good needle to fit is an ABC. This seems to perform well on the 2cv engine.
After a strip down and rebuild it's vital that the dash pot piston drops freely onto the bridge with a "clunk"
There is lots of info on net about these carbs including one called "Mintylamb" on which you can compare the various needle profiles
I hope the above gives you some help.

hi ron,
also an obvious, but can be overlloked after a full strip down and clean. replenish oil in dashpot. no oil will result in a big splurge of fuel on crank over.

bob

Thank you all for your comments and assistance. At least it is confirmed that it's an HIF carb that I've got. Being the full Blackjack conversion I would hope that needle etc is somewhere near correct. I've obviously done something wrong when putting it all back together so.....best start from scratch again...just B......frustrating.
PSNow got a printout of the carb and tuning etc so.....fingers crossed Cheers

Hi Guys...To all those that came to my assistance....Many Thanks. The info you gave was invaluable and ...after a struggle...I've got it sorted !! Hip ,hip hurray !! Car now starts , runs and even ticks over !! but not much else at the moment as I've got No exhaust !! so it's a bit noisy !! Thanks again ..one and all. Regards Ron

There is a Facebook page for blackjack avions and Geof a chap who is knowledgeable I think there are two versions of the adapter as they didn't get it "ideal " the first time . I have Geoff's number if you pm me