Have changed carby from a weber to 1.5" SU & can`t get the bugger to start.

motor winds over fine but just wont start. had this problem with the weber on it had the mechanic sort it & the timing was miles out, could this be the problem with having changed the carby ?

cheers
jayson

If it was running OK with the Weber, the timing should definitely be well and truely in the ball park for the SU.

Checked the needle & seat in the float bowl isn't jamed closed?

Jet not blocked?

Choke working?

Take the Bell off the carb and have a look down the jet, you should be able to see the fuel level.

Is the needle close for your applcation?

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no, if the timing was right before, it'll still be right now

basic checks first...

is the float bowl full of fuel? (if no, then the needle and seat is stuck, un-stick it)
do the spark plugs smell of fuel? (if no, then unscrew the big nut under the carb 1/2 a turn and see what it does)

and then you'll have a million more suggestions of what it'll be

beat me GT

thanks,will have a look at this tomorrow hopefully it will have stop snowing by then.

car is now starting & running.

needle seemed to be moving freely,adjusted the mixture nut half a turn down & started fairly easy.

thanks for the advice.

what needle would you run in a mild 1275 ? currently has a 5.

cheers
jayson

Hi Jayson, good to hear you got it started.

My vizard bible says a good starting needle to try on a 1275 non-S engine with a normal mixture is a DZ with a red spring in the dash pot.

if you want a richer mixture from there, vizard recommends a BQ needle and red spring for a 1275 non-S engine.

If you have access to a rolling road or dyno tuner, i recommend having it setup correctly that way.

otherwise, buy a few different needles and experiment yourself until you feel it is right for you. try the 5 and 6 and see how they go.

i recommend getting a copy of david vizards " tuning the A series engine" 3rd edition. a very good read.

good luck

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'66 BRG Morris Mini Deluxe 60HP ATW