4 replies to this topic

[clubman katie B.F]

hola. just rebuilt kaqtie's engine. it's a 1275, A-plus, based engine, with a Swiftune sw5 cam, basically, running on a HIF44, and electronic ignition, just got her started, and she is running really rich, and sounds like a traaaactor (by rich i mean, the sparky plugs were black with soot after 10 mins running). any suggestions of carb needles would be much appreciated, currently she is running on a BDL. or any tuning/fettling suggestions would be great, cheers all.

[clubman katie B.F]

anyone?

[Guess-Works.com]

As a starting point the BDL is a decent enough needle, and for it to be running rich with that on means your jet is way too low....

Try weakening the mixture until it starts to hunt ( labour ) then richen until idles comfortably ( should only be about 1/2 turn max )

If when you now open the throttle and it bogs down, it may be an idea to check the timing and then using a colour-tune to get the mixture closer at idle.

Needle selection itself is very specific to the engine and setup. It can be done on your drive, but a few quid spent on a rolling road session would be money sell spent.

[clubman katie B.F]

cheers guessworks.....you are a star. seems to be getting a bit better. when we dropped the gearbox on to the engine, we had the engine upsideown so we think maybe some old oil got somwehre is shouldn't have

[royallingham]

Don't worry about Colourtune - just test the idle mixture by lifting the carb piston. If it speeds up - too rich, if it stalls - too weak. But this is only the idle mixture - you need to do a good hard power run up a long steep hill - then switch off, coast to a halt - whip out the plugs and see the colour. White is too weak, black is too rich - you want light brown. Based on this you can decide is a different needle is required. A RR sesssion will help - but they ain't cheap !