30 replies to this topic

[Jamie_RoverMini35]

hi there this is my first post on here so be nice so today we fitted a weber 40 on my fairly standard 1275 mini, it has a mechanical fuel pump and no regulator(just to get that in there)... anyway, when you start the car the rev's jump away up to around 3,000 rpm maybe more and stay there popping and backfiring, we have checked for air leaks all around and there was no problems, some times fuel even come out from the trumpets .. seriously confused ! i was thinking fuel pressure was to high and the float was not shutting the fuel off and it was filling itself up and escaping everywhere making the engine idle very eratically.
any help is very much appreciated
cheers !
Jamie

[oltonlad]

are you sure that there isn't an air leak?............have you put new seals on from the carb to the manifold?..........and are you sure that the carb body isnt cracked anywhere.

[Jamie_RoverMini35]

thanks for the fast reply ! yeah the carb was fully rebuilt and got a new manifold yesterday so that came with the new seals for manifold to carb.. sprayed everything with wd-40 to test for air leaks and no difference... inspected the carb and there was no cracks that i could see.

[Jamie_RoverMini35]

hi there, the throttle isnt connected at the moment so it wont be that.... ok ill try that tomorrow bit too noisy to try that the now haha.. im sure we tried that but no harm in trying again its just starting and revving very high and wont go down no matter what we do

[Jamie_RoverMini35]

should the linkage really effect the running? the carb came with a home made kind of job.... it does work well, the carb is properly fitted also just dont have the cable connected up...

[Jamie_RoverMini35]

yep it has a spring return

[bmcecosse]

Well - there MUST be air getting in or the engine wouldn't run at all.... Close the throttles completely - and as mentioned in another place - weber 40 is too small to be effective on a 1275. You would be better off with an HIF 44 - much easier to set up too......

[Jamie_RoverMini35]

the throttles are fully closed, no choke and the idle screw is fully out and the rev's are very high ! i also should mention we took the brake servo pipe off at the servo and the rev's dropped slightly but ran just as bad... and when you put you're finger back over it they went shooting up again, im guessing this may be getting far to much fuel into the car? do i need a pressure regulator or does the float need adjusted...?

[oltonlad]

i have run webers with a mechanical fuel pump and without a pressure regulator in the past and have never had problems..............what car is the carb from?.........its obviously not jetted for a mini, you need to see what jets are fitted first and take it from there really.

[Jamie_RoverMini35]

its of an a series anyway..... won it on ebay a few week back, fully refurbished the seller had loads of positive feed back and no one had any problems, it was jetted for a 1275 mini in the description but can only take peoples word for it.......

[Jamie_RoverMini35]

wouldn't it still idle roughly but reasonable if it wasn't jetted correctly, not just shoot away up like this is doing?
om sure we had the jats out earlier and i read 127 on something and F16?

[bmcecosse]

Air must be getting in - close the throttles completely....and go on from there. 127 sounds like main jet (quite small??) and F16 is the emulsion tube....

[Jamie_RoverMini35]

okay thanks ill try loads off things tomorrow and report back

[oltonlad]

to be honest, i would never a weber from ebay, i've only ever purchased weber's or dellorto's either new or if i know and heard the car that they came from, especially when the prices are as much as they command on ebay, people pay ridiculous money for them.

[Jamie_RoverMini35]

i don't mean the idle mixture screw is fully out, i just meant the idle screw.... very confused, will check for air leaks again today, try adjusting the float etc etc