30 replies to this topic

[Jamie_RoverMini35]

ok todays update, I have came to the conclusion that the fuel pressure was too much... fuel regulator on the way i think...

[Jamie_RoverMini35]

yep tried adjusting the mixture screw and it made very little difference if any, today we clamped the fuel pipe a small amount (not fully) and the car idled better and took adjustments....

[Jamie_RoverMini35]

it only made a very slight difference when i screwed them in before i clamped the fuel line... which jets are the idle jets?

[pogie]

Not sure if this will help but I had a similar problem with a 45 DCOE which turned out to be caused by the lever arm supplied with the Weber Throttle Linkage Kit. Even with the tick over screw removed from the carb body the lever was still holding the throttle open so I filed a couple of mm off the lever's throttle stop and everything was good. I knew it had an air leak but I couldn't work out where from and I only found the problem when I took the carb off and held it up to the light and I could see the tiniest gap around the butterflies.

Edited by pogie, 06 May 2012 - 06:13 PM.

[Jamie_RoverMini35]

funny you should say that, when the carb is off the car the "flaps" inside... butterflies? look open .... should these be sitting flat or open slightly?
not sure that is the problem though but might be worth investigating further, id say it will be the fuel pressure making the float ineffective and allowing far too much fuel to enter the engine and everywhere else for that matter

[bmcecosse]

Too much fuel would just flood it - the problem is AIR !! The engine can't run unless it has air - more air, the faster it will run, provided there is some fuel flying around.

[sonikk4]

You say you have fitted new seals, what type. Is it the plastic type with two seals either side or the Misab type with the seals bonded to the metal plate??

Have you over tightened the Thackery washers??

To be honest with you you could spend hours messing around with jets and setting up etc. Take it to a rolling road which specialises in Weber carbs and get it set up properly. If there is too much fuel going into the engine then you will wash the bores causing premature wear.

[oltonlad]

please dont take what i am about to say the wrong way..........but you really need to get this sorted out by someone who knows what they are doing, people are trying to advise you on here but you really dont seem to have a clue what they are talking about, i know that we all have to start somewhere but messing about with a carburettor such as a side draught weber really needs to be done by someone who knows about them, apart from that you may do more harm than good by messing about with it yourself.

[pogie]

funny you should say that, when the carb is off the car the "flaps" inside... butterflies? look open .... should these be sitting flat or open slightly?
not sure that is the problem though but might be worth investigating further, id say it will be the fuel pressure making the float ineffective and allowing far too much fuel to enter the engine and everywhere else for that matter

The butterflies (flaps) should be completely closed with the tickover screw removed, I was surprised at how small the opening that caused all my problems was. It's worth taking a couple of minutes to remove the levers from the side of the carb and then hold it up to look and see if any light is getting past them, there should be none.

P.S. Be careful not to move the levers and squirt petrol into your eyes from the pump jets!!!!

[Jamie_RoverMini35]

thanks ill go try that tonight any ideas about the fuel coming from the trumpets? float valve needing adjusted?

[Jamie_RoverMini35]

yess problem solved, the idle lever wasn't shutting the butterflies chuffed its fixed, however still got a wee bit fuel dripping from trumpets? any idea's folks?...

[Hegnirst]

i too would love to know about the fuel dripping from the trumpets as im having this exact problem now

[sonikk4]

Have you had the carb set up on a rolling road?? It could be down to the fact that you are still running rich or your carb is backing out of the trumpets. Either way these carbs really need to be sorted correctly or like i previously said you can end up with bore wash and ruin your engine.

[Hegnirst]

Backing out of the trumpets? What does this mean? Ad sorry to hijack this thread but whilst we're talking about them, with them it will rev up to 4k without me touching the throttle :S and it will be very juddery unless I floor it. But I I force it down to 1K by brake with out the clutch it will stay there. I want to know if there is anything I can do till I get it on the rolling road next week. Thanks for the help in advance!

[sonikk4]

Hegnrist sounds like you have an issue with the linkage so worth checking that out. On my twin 45's i had basically backfiring through the bell mouths as the carbs were not properly balanced and jetted correctly. I did reset the idle screws back to the stops and then adjusted from there but the balancing i could not do due to not having the correct tools. (it was difficult then as i was in Germany with the RAF at the time)

However once it was on the rolling road back in the UK and two hours later they ran sweetly and i had a cheeky 124 bhp at the rear wheels.