Wow! You seem to know what you're talking about, and further back up my suspicions, that the needle isnt correct and therefore the mixture isnt correct causing flat spots, or juddering whilst under acceleration.The carb jet needle is not the correct profile for the engine. As the engine is now breathing through a high efficiency filter and intake manifold and exhausting through a more efficient exhaust manifold and silencer the original needle will be no use, even the needle supplied with the kit will not be spot on( as many have found out on here).It would appeare as if the carb is leaning out the fuel mixture a little( proved by you using the choke slightly and it running better). It is more noticeble now as the ambient air temperature is now a lot cooler and hence, denser, containing more oxygen, further leaning out the fuel mixture.
You realy need to check that the needle is some where near, I think the stage one kit is an 'AAA' needle. If it still has the original needle in the carb, then order up an AAA before you go to the rolling road session.( I ordered one from minisport and it took weeks, but that was years ago, phone them up and see if they got any and will have on the day) That way when its on the rollers the operator has a much better chance of getting it fueled rightIf its the same bloke from a few years back, then he does a top job
To find out which needle you have, remove the three screws from the base of the dashpot and carefully lift the whole thing off remembering that the needle protrudes from the bottom and is easily bent. The needle is fixed into the piston by a flat head screw, which locks the retaining coller at the base of the needle. Loosen this screw just a couple of turns(theres no need to remove it) and withdraw the needle, spring and coller. DO NOT LOOSE THE SPRING. The needle spec is written on the part of the needle normaly hidden by the retaining collar, usualy three letters but on rare instances two. Re assemble making sure the retaining collar is flush with the piston. Five miniut job :cheese:
Now if there is still an aluminium identification tag on the carb, usualy fixed by one of the dashpot screws you removed earlier, you can use this number on here http://www.burlen.co.uk to find out what needle was fitted to the carb at the factory when it was used in production and what car it was used on, listing all the parts as spares or a complete new item.
This may also help select the correct needle http://www.winsu.co.uk/
Other than this there is an air leak
Does that sound about right?
Its too dark now, but tomorrow i'll do as you just explained, and find out what needle is in it - Just to check, the needle can only be seated in one position cant it, meaning i cant mess up settings by removing and putting it back together? (sorry, i know bikes, but not cars yet :doh:)
If i have to order up a different needle, how much is that likely to cost me? just a few pounds?
Cheers, your help is much appreciated.
Adam
