prawnabie
|
| posted on 13/3/10 at 02:28 PM |
|
|
Weber help needed please!!
Hi guys
I have fitted a new manifold to my crossflow and decided I might as well rebuild the 40 webers before I put them back on the car. I completly stripped
and cleaned them, I used two genuine service kits and replaced the misabs/mounts aswell.
Now that I have fitted them and bolted everything back up, I have found I have a problem with the rear most carb. The engine has a definate misfire on
idle, when you put a pipe into the carb mouth on the front carbs, you can hear a constant sucking noise. When you do the same to the rear carbs, you
can hear a "popping" noise from both chokes.
I had a quick look this morning, reset the timing to 10btdc and screwed the mixture jets out 7 turns from fully in on all the carbs. I also did the
same with the air bleed screws - still the same!!!
I have noticed that the exhaust was MUCH hotted on the same end of the engine that the misfire was on, giving me the impression it was running lean
very lean, so I ended my investigation there lol. I am going to take it to the rollers when i get paid, but i really need to drive it there as I
don't have a trailer.
Anybody have any idea what i can check next? It was working fine until i stripped it lol! P.S i have spark on all 4 plugs!
Thanks
Shaun
|
|
|
|
|
TigerB6 Paul
|
| posted on 13/3/10 at 02:36 PM |
|
|
Sounds like it needs the inter-carb balancing setting up for starters. Have a look visually down the throats and see if the butterflies look to be
opening at the same time and the same amount. This may give you a clue
|
|
|
prawnabie
|
| posted on 13/3/10 at 02:41 PM |
|
|
Thats a good point actually. I did adjust the linkage so that they opened at the same time, but I neglected look down the chokes to look at what was
happening!
|
|
|
TigerB6 Paul
|
| posted on 13/3/10 at 02:45 PM |
|
|
I'd give that a go to try and balance it better before looking for a reassembly fault
|
|
|
prawnabie
|
| posted on 13/3/10 at 02:57 PM |
|
|
Does anyone know if the chokes are handed to either side of the carb?
|
|
|
TigerB6 Paul
|
| posted on 13/3/10 at 03:25 PM |
|
|
The choke mechanism or the chokes that slide down the barrel of the carbs that can be changed for different sizes - 34mm / 36mm etc?? I did lose the
locating screw on a Dellorto choke once - it allowed the choke to rotate and cut the fuel supply!!
|
|
|
prawnabie
|
| posted on 13/3/10 at 04:12 PM |
|
|
The ones in the webers have two cut outs in the for the pump jet to fit into, there is no locating peg on them. just wondered if I could have fitted
them wrong on one carb.
|
|
|
britishtrident
|
| posted on 13/3/10 at 07:00 PM |
|
|
Balance the throttle butterflys
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
|
|
|
prawnabie
|
| posted on 13/3/10 at 07:05 PM |
|
|
Thanks guys I will pop up to work tomorrow morning and have another crack.
One last thing, is there are ballpark setings for idle mixture screws and airbleed screw kicking around?
Cheers
|
|
|
skibikejohn
|
| posted on 13/3/10 at 07:25 PM |
|
|
Idle mixture will be about 1.25 turns out from lightly seated.
|
|
|
skibikejohn
|
| posted on 13/3/10 at 08:46 PM |
|
|
If by "air bleed" you are referring to the "idle by pass" circuit then Hamlin, in "How to build and power tune Weber and
Dellorto .... Carburettors" suggest that tuning is easier if you make the idle by pass inoperative by screwing the screw the whole way in. You
then only have to change the idle mixture.
I hope this helps.
|
|
|
